Next Article in Journal
Alston Virus, a Novel Paramyxovirus Isolated from Bats Causes Upper Respiratory Tract Infection in Experimentally Challenged Ferrets
Next Article in Special Issue
Small Animal Models of Respiratory Viral Infection Related to Asthma
Previous Article in Journal
A Subunit Vaccine Based on E2 Protein of Atypical Porcine Pestivirus Induces Th2-type Immune Response in Mice
Previous Article in Special Issue
Pathobiological and Genomic Characterization of a Cold-Adapted Infectious Bronchitis Virus (BP-caKII)
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:

Immunocompetent and Immunodeficient Mouse Models for Enterovirus 71 Pathogenesis and Therapy

Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
Institute of Microbiology and Immunology, National Yang-Ming University, Taipei 11221, Taiwan
Author to whom correspondence should be addressed.
Viruses 2018, 10(12), 674;
Received: 1 November 2018 / Revised: 23 November 2018 / Accepted: 26 November 2018 / Published: 28 November 2018
(This article belongs to the Special Issue Animal Models for Viral Diseases)


Enterovirus 71 (EV71) is a global health threat. Children infected with EV71 could develop hand-foot-and-mouth disease (HFMD), encephalitis, paralysis, pulmonary edema, and death. At present, no effective treatment for EV71 is available. We reviewed here various mouse models for EV71 pathogenesis and therapy. Earlier studies relied on the use of mouse-adapted EV71 strains. To avoid artificial mutations arising de novo during the serial passages, recent studies used EV71 clinical isolates without adaptation. Several human receptors for EV71 were shown to facilitate viral entry in cell culture. However, in vivo infection with human SCARB2 receptor transgenic mice appeared to be more limited to certain strains and genotypes of EV71. Efficacy of oral infection in these transgenic models is extremely low. Intriguingly, despite the lack of human receptors, immunodeficient neonatal mouse models can still be infected with EV71 clinical isolates via oral or intraperitoneal routes. Crossbreeding between SCARB2 transgenic and stat1 knockout mice generated a more sensitive and user-friendly hybrid mouse model. Infected hybrid mice developed a higher incidence and earlier onset of CNS disease and death. Different pathogenesis profiles were observed in models deficient in various arms of innate or humoral immunity. These models are being actively used for antiviral research.

Graphical Abstract

1. Introduction

Enterovirus 71 (EV71 or EV-A71) was first isolated from the stool of encephalitis patients in California in 1969 [1]. It is a positive-strand RNA virus, belonging to the Picornaviridae family [2,3]. The genomic structure of EV71 is as outlined in Figure 1. Similar to poliovirus and other plus-strand RNA viruses, it contains an IRES element, which drives the translation of a polyprotein from a 7.4 kb genomic mRNA template. Upon protease cleavage, this polyprotein precursor can then convert into various smaller-size structural and non-structural proteins, leading to capsid assembly. As the focus in this review is about pathogenesis and animal models, readers interested in the EV71 replication cycle are advised to consult other reviews in literature.
Adults infected with EV71 could develop subclinical or cold-like syndrome. However, children younger than five years of age could develop hand-foot-and-mouth disease (HFMD) and herpangina. In severe cases, EV71-infected children could develop aseptic meningitis, encephalitis or myocarditis [6]. In a long-term follow-up study, EV71-infected patients with CNS involvement and/or cardiopulmonary failure was associated with delayed neurodevelopment and reduced cognitive functioning [7]. Unfortunately, some patients were still not saved due to pulmonary edema and/or heart failure [8].
Although EV71 was first discovered in the US decades ago, recent major outbreaks occurred frequently in the Asia-Pacific region, including Taiwan, Singapore, China, Malaysia, and Japan [6,9,10,11,12]. China alone reported 1894 deaths between 2008 and 2011 [12]. Sporadic cases were also reported from Europe [13,14], Russia [15] and Australia [16], indicating that EV71 is a global health threat. Like poliovirus in the last century, EV71 is emerging rapidly as another pathogenic picornavirus for children in this century.
Intravenous immunoglobulin (IVIG) is a therapeutic strategy for EV71-associcated brainstem encephalitis [17]. However, an antibody-dependent enhancement (ADE) phenomenon was observed in EV71-infected patients [18,19,20,21], suggesting that IVIG may not be the most adequate treatment in clinical practice. Milrinone, a phosphodiesterase inhibitor, was used to treat patients with EV-71 induced pulmonary edema (PE). While Milrinone is not an antiviral per se, mortality was significantly decreased in the Milrinone-treated group, suggesting that it could be a useful therapeutic drug for EV71-associated PE [22].
To investigate the pathogenesis and therapy for EV71 infection, we will need both in vitro and in vivo models of EV71 infection. In this review, we cataloged here from the literature a total of 16 cell lines (Table 1) and 22 animal models (Table 2), which had been tested for EV71 infection and pathogenesis. We compare below their respective advantages, limitations, and caveats in using these models.

2. In Vitro Propagation Systems

The most common cell line for EV71 infection in culture is the human RD cell line of rhabdomyosarcoma origin [23]. This RD cell line can produce a high yield of virus particles and thus is often used for amplification of EV71 in animal experiments [4] and studies on viral structure [56]. In addition to RD cells, various cell lines used in poliovirus infection, such as HeLa and HEK293, are also susceptible to EV71 infection and transfection [36,37]. These cell lines were used as a platform to investigate the function of viral protein. From clinical samples, EV71 protein can be identified in brainstem [6,57], and thus EV71 is considered as a neurotropic virus [1]. Several neuronal cell lines, including SK-N-SH, NSC-34 and SF268, had been used in a number of studies, such as dissecting the viral life cycle, host response to EV71 [33], phylogenetic analysis [24], and anti-viral drug testing [34]. In natural infection, EV71 is transmitted through an oral-fecal route [58]. Some previous studies therefore focused on the GI tract immune responses to viral infection and replication kinetics in the intestinal epithelial cells [25,26].
Using the Jurkat cell line and an expression cloning strategy by panning, Nishimura et al. identified human P-selectin glycoprotein ligand-1 (PSGL-1; CD162) as a functional receptor on leukocytes for EV71 viral entry [59]. However, PSGL-1 cannot be the only receptor for EV71, since PSGL-1-independent infection in non-leukocytes was also observed. Yamayoshi et al. reported that human scavenger receptor class B, member 2 (SCARB2, also known as lysosomal integral membrane protein II or CD36b like-2) is another receptor for EV71 [60]. The exogenous expression of human SCARB2 converted non-permissive cell lines to instead support EV71 propagation and develop cytopathic effects. EV71 infection can be interfered by the antibody to SCARB2 or by soluble SCARB2. Several alternative receptors for EV71 have also been reported [61,62,63,64].
In addition to Jurkat cells, THP-1 and human PBMC had been used to study the innate immunity in EV71 infection [37]. Many other cell lines contributed to the studies on EV71 molecular virology, virus-host interactions, or drug screening (Table 1). So far, the human rhabdomyosarcoma cell line RD appeared to be the most commonly used gold standard in literature, in part due to its high yield production of different EV71 genotypes [65]. As more and more laboratories are using the same RD cell line (e.g., from ATCC), it would be easier to cross-compare results from different laboratories. Since these cell line models are limited one way or the other in their resemblance to human natural infection, an alternative approach is needed to validate the findings from the cell culture system. In this regard, animal modeling can provide more complete and convincing evidence for our understanding on EV71 in vivo infection and pathogenesis.

3. In Vivo Animal Models

Experimental results learned from the cell culture system need to be validated in animal models and human clinical trials. Table 2 summarizes different EV71 mouse models reported in literature so far. Overall, one thing in common in these different models is their frequent use of limb paralysis and mortality for scoring disease severity. This is in part due to the fact that paralysis and death are more apparent, objective, and convenient phenotypes than other parameters, such as ataxia, or pulmonary edema. Another common feature is the requirement of a neonatal host age for productive in vivo infection, in particular with clinical isolates. Although the exact mechanism for this young age requirement remains unclear, it is technically demanding and not user-friendly, when the newborns are too small and fragile to handle experimentally. When tissue cytokine/chemokine profiles were examined in these different EV71 mouse models, they were often found to share some inflammatory cytokines in common, such as IL1β, IL6, IL10, IP10, MCP-1, IFN-α, and IFN-γ, etc. [4,52,53]. For neuropathogenesis models, the distribution of viral antigens is also quite similar among different models, which mimics human cases with fatal encephalomyelitis. For example, inflammation and viral antigens in human cases were observed mainly in the spinal cord, brainstem, hypothalamus, cerebellar dentate nucleus, and cerebrum [66]. In the stat-1 KO model, VP1 was strongly expressed throughout the entire spinal cord, including the anterior horn and the gray matter [4]. Furthermore, VP1 in the pons of the brainstem, but not in the cerebral cortex, supports the concept of retrograde axonal transport from the peripheral nerves to the spinal cord ascending to the CNS. This result is supported from the mouse models infected with mouse-adapted EV71 strains [67,68] and poliovirus [69].
As summarized above, there is a high degree of similarity among EV71-infected human patients and mouse models. However, there are also important differences among these mouse models, which will need to be discussed individually.

3.1. Mouse Models Dependent on Mouse-Adapted EV71 Strains

In general, adult humans are resistant to EV71 infection and pathogenesis. Similarly, adult mice cannot be easily infected with EV71 clinical isolates. To solve this problem, researchers developed mouse-adapted strains of EV71, such as MP4, in an ICR mouse model [21,27,44,45,46]. MP4 was generated through i.p. injection of the parental EV71 TW/4643/98 into one-day-old ICR mice. Adapted EV71 recovered from the brain tissue was re-used to repeat the serial injection-adaptation cycles. EV71 recovered from the fourth passage was designated as MP4 [27]. Comparing to its parental EV71 isolates, MP4 is more cytotoxic with a larger plaque size. Because EV71 is a RNA virus with a quasi-species nature, mouse-adapted strains tend to accumulate many artificial mutations from the serial passages. One legitimate concern is that these adaptive mutations cannot really be found in human natural infection. In addition to MP4, mouse adapted strains were also generated in the immunodeficient NOD/SCID mouse model [55]. Comparison of the amino acid sequences between clinical isolates and mouse adapted strains revealed major differences in structural proteins, such as VP1, VP3, and protease 2A [55]. Therefore, it always remains uncertain whether results obtained from using the adapted strain of EV71 can be automatically extended to human natural infection with the clinical isolates.

3.2. Immunodeficient Mouse Models

Host immune system plays a critical role against viral infection [70]. Immunodeficient mice, even without bearing any human receptors for viral entry, can support infection with EV71 clinical isolates, instead of relying on mouse-adapted strains. Innate immunity, such as IFNs, is required for protection from EV71 infection and pathogenesis [71,72]. AG129 mice, which is deficient in both α/β and γ interferon receptors, developed limb paralysis and death, when infected with a non-mouse-adapted EV71 via i.p. or oral routes. Viral protein was detected in CNS in both i.p. and oral infection [53]. Like mouse AG129, mouse A129 (deficient in α/β interferon receptor) can also be infected with mouse-adapted strain of EV71 [54]. Moreover, mouse G129 deficient in γ interferon receptor developed limb paralysis via an i.p. route with clinical isolates of EV71 [4] (Table 2). Another host factor stat-1 is a key transcription factor in IFN signaling. The stat-1 knockout (KO) mice can be successfully infected with both genotype B and C clinical isolates of EV71 [4,5]. Infected stat-1 KO mice developed hindlimb paralysis with abundant viral protein in the CNS system, supporting an important role of IFN signaling in protecting CNS from EV71 infection and pathogenesis.
In addition to innate immunity, humoral immunity also plays an important role in EV71 infection and pathogenesis. For example, injection with an EV71-specific neutralizing antibody before or after infection, can strongly reduce lethality and tissue viral loads of a mouse-adapted strain M2 in a B cell-deficient C57BL/6-derived mouse model [44]. In another example, NOD/SCID mice deficient in T and B lymphocytes can be infected with a mouse-adapted strain of EV71 [55]. However, since mouse-adapted EV71 can infect even immunocompetent mice [27], it was unclear if the missing T and B lymphocytes in the NOD/SCID mouse model were really important for protection from mouse-adapted EV71 [55]. This issue was addressed in one study when NOD/SCID mice were inoculated with EV71 clinical isolates and developed limb paralysis via either an i.p. or oral route. Although limb paralysis has been used as a common marker for scoring EV71 pathogenesis in mouse modeling, acute flaccid paralysis does not occur as frequently as hand-foot-and-mouth disease (HFMD) in human natural infection. Interestingly, in the NOD/SCID model infected with clinical isolates, an HFMD-like phenotype with skin rash was observed, for the first time in mouse models [4]. Spleen atrophy was found in some EV-71 infected children [57,73], and was also noted in this NOD/SCID model infected with clinical isolates [4]. Moreover, strong VP1 staining and severe inflammation were apparent in the paralyzed muscle. On the other hand, no viral protein and pathology was ever detected in the CNS in EV71-infected NOD/SCID mice. It is worth mentioning here that in this NOD/SCID model, kinetic analysis in a time course experiment revealed more delayed clearance of non-infectious viral RNA relative to the clearance of infectious viral particles [4]. Furthermore, the inflammatory IL-23/IL-17 axis appeared to be activated in the infected NOD/SCID model. It remains to be seen whether these intriguing phenomena are idiosyncratic to the NOD/SCID model, or they can be generalized to other mouse models or human patients.
Interferon-gamma-inducible protein-10 (IP-10) is a highly expressed chemokine in EV71-patients [74]. IP-10 knock-out mice infected with mouse-adapted EV71 exhibited a higher mortality rate than the wild type control mice, suggesting a protective role of IP-10 in EV71 infection and pathogenesis [49].
While the immunodeficient models are very useful for studying pathogenesis and evaluating efficacies of drug and vaccine candidates, it is not always a good system for testing immune modulators in therapeutic research. In addition, it is not as direct a platform for vaccine research either, since it can only be used for comparing potencies of anti-EV71 neutralizing antibodies raised against different vaccine candidates.

3.3. Transgenic Mouse Models

Recently, many cellular receptors have been proposed for EV71 viral entry in vitro, including hSCARB2 (human scavenger receptor class B) [60], PSGL1 (P-selectin glycoprotein ligand 1 [59], annexin II [61], and nucleolin [62]. These receptors facilitated EV71 infection in non-susceptible cell lines, such as mouse fibroblast L929. However, transgenic (Tg) mice expressing human PSGL-1 failed to support infection with EV71 clinical isolates [50]. Among these reported cellular receptors, only human SCARB2 (hSCARB2) has so far been shown to support EV71 infection in vivo.
There are two different hSCARB2 Tg mouse models in literature (Table 3) [51,52]. In the EF-1a-hSCARB2 model, EF-1a promoter is used to drive hSCARB2 expression in the C57B/6 mouse background [52]. In the SC2-hSCARB2 model, the native hSCARB2 promoter in a human SCARB2 BAC clone drives the transgene expression in the C57B/6 mouse background [51]. Both models can be infected with EV71, develop limb paralysis, and detect viral protein in multiple tissues, including muscle (muscle-tropism) and the CNS system (neurotropism). On the other hand, these two models cannot be easily compared with each other due to a number of differences (Table 3): (1) virus strains and genotypes (B4, B5, C2, C4 vs. Isehara); (2) host age at virus inoculation (1- or 7-day-old vs. 3-wk-old); (3) virus dose (PFU vs. TCID50); (4) inoculation route (s.c. vs. i.c., i.v., i.p.); (5) assays for readout (individual score of paralysis & death vs. combined score of ataxia, paralysis, and death). In addition to the Isehara strain (gt C2), other genotypes of EV71 were tested in the SC2-hSCARB2 model [51]. However, since the non-Tg wild type mouse control was included only in the study using the Isehara strain, we listed here in Table 3 only the results based on the Isehara strain.
In the pEF-1a-hSCARB2 transgenic mouse model, limb paralysis rate cannot be differentiated between Tg and non-Tg control mice, when EV71 gt B4 or gt C4 are used (Table 3) [52]. However, mortality rates between Tg and non-Tg are different for gt C4; and the incidences of earlier symptoms are different between Tg and non-Tg, when gt B4 was used. Despite the limitation in host age and susceptibility to certain EV71 genotypes in this pEF-1a-hSCARB2 transgenic model, it had been used in evaluating the efficacy of EV71 vaccine or adjuvant [75]. The Isehara strain behaved like a strain with a high degree of virulence. For other viral isolates, such as BrCr, SK-EV006, and C7, much higher viral doses were required for developing neurological symptoms in the hSCARB2-Tg10 mouse model. In fact, even subcutaneous infection of the neonatal non-Tg control mice with the Isehara strain caused paralysis [51]. In addition to the CNS, viral antigens were detected in skeletal muscle of both non-Tg and Tg mice. In this regard, the hSCARB2 Tg mice are similar to the NOD/SCID mice in supporting the replication of muscle-tropic EV71.
Neither model of these hSCARB2 Tg mice has so far been shown to support efficient oral (intragastric) infection, which is a major route for transmission in children [51,52]. Before these models are shown to be susceptible to a broader source of different clinical isolates and genotypes, it is a caveat to carefully choose the best EV71 strains in the experimental design based on the hSCARB2 transgenic model.

3.4. A Hybrid Mouse Model

As discussed above, both hSCARB2 receptor and immune deficiency can contribute to efficient EV71 infection and pathogenesis. Therefore, it is possible that a combination of a transgenic hSCARB2 and host immune deficiency might further enhance infection efficiency. Indeed, a new hybrid mouse model was generated by cross-breeding hSCARB2 Tg and stat-1 KO mice. Comparing to its parental hSCARB2 Tg or stat-1 KO mice, this hybrid mouse model is more user-friendly. For example, at 2-week-old age, it can still be i.p. infected with different genotypes of EV71 at 1000-fold lower titer (pfu) than the parental mice [5]. EV71-infected hybrid mice exhibited high density of viral protein in the CNS, such as mid-brain and spinal cord. Like the stat-1 KO model, although EV71-infected hybrid mice developed limb paralysis, neither viral RNA nor protein was ever detected in the muscle. It suggests that paralysis originated solely from the CNS injury, rather than myositis and muscle destruction. This new hybrid (hSCARB2 Tg/stat-1 KO) model could serve as a user-friendly platform for evaluating drug or vaccine efficacy [5].
Although this hybrid mouse model is a far more sensitive system for studying EV71-associated neuropathogenesis and antiviral therapy, it is deficient in interferon signaling. Therefore, it is not a good model for studying the therapeutic potential of immune modulators.

4. Pathogenesis Mechanism

Disease manifestations in EV-71 infected children are very diverse, ranging from subclinical infection, common cold-like syndromes, hand-foot-and-mouth disease, to uncomplicated brainstem encephalitis, severe dysregulated autonomic nerve system, fatal pulmonary edema, and cardiopulmonary collapse. To date, while neurological disorders can be modeled in stat-1 KO mice, hybrid mice, and hSCARB2 Tg mice, pulmonary edema and cardiopulmonary failure remain to be recapitulated in EV71 mouse models. Because viral protein has never been detected in patients’ cardiomyocytes, it is generally believed that cardiopulmonary failure is caused indirectly by the dysregulated autonomic nerve system in the infected brainstem. Depending on the combination of both viral and host factors, current EV71 animal models could develop a wide variety of pathogenesis similar to human infection. The viral factors include the infectious dose of EV71, genotypes, mutations, and possibly, sequence heterogeneity (quasispecies). The host factors include the innate and adaptive immunity, routes of virus inoculation, and the critical host age receiving viral infection.

4.1. Viral Determinants of Virulence

In the case of viral factors, both viral load and sequence variations of different EV71 isolates could significantly contribute to different degrees of virulence and clinical outcome. In the 1970s, EV71 epidemics occurred in North America and Europe (genotype A, B1, and B2) and showed a higher percentage of paralysis than the dermatological symptoms [76,77]. In contrast, clinical reports in Asia-Pacific after the 1980s (other than genotype A, B1, and B2) observed both dermatological and neurological symptoms [3,21,45]. Comparison of these results suggested that differences in ethnic groups or/and genotypes of EV71 may have different sequelae. Sequence analysis identified some nucleotide or amino acid differences between fatal and non-fatal cases [78,79,80]. For example, it has been shown that point mutations at amino acid 145 of VP1 or amino acid 149 of VP2 could determine whether neonatal mice can or cannot be successfully infected with a mouse-adapted EV71 strain [55,81]. In addition to the coding sequences, adaptive mutations at the IRES region also affected the virulence in mice [82]. Finally, tissue tropism could also be associated with viral sequence variations. Sequence comparisons of different EV71 isolated from respiratory, gastrointestinal, CNS, and blood specimens, revealed nucleotide differences at three different positions. Further study showed that amino acid 97 of VP1 was critical for neurotropism [83]. Both amino acid 97 and amino acid 145 of the capsid protein VP1 were further investigated by two different research groups for their contribution to pathogenesis in hSCARB2 Tg and non-Tg mouse models, respectively [84,85]. VP1 mutant L97R was thought to be more virulent, because it acquired better binding to heparan sulfate on the target cells [85]. Heparan sulfate is a common attachment receptor for many viruses, including EV71 [63]. In contrast, VP1 mutant 145G was thought to be less neurovirulent than VP1 mutant 145E, due to its better binding to heparan sulfate than mutant 145E [84]. It was proposed that VP1-145G virus is preferentially adsorbed by heparan sulfate attachment receptors on an excessive number of non-target cells during circulation in vivo, leading to trapping and attenuation of mutant VP1-145G. In summary, it would have to be resolved in the future, whether heparan sulfate binding property of EV71 capsid protein VP1 and in vivo viral virulence, are positively or negatively correlated.

4.2. Host Factors

In this section, we will focus our scope on only those host factors which were investigated in animal models. In one previous study [4], mouse models with different immunogenetic backgrounds were i.p. infected with the same clinical isolates of EV71, and different disease outcomes and viral tropisms were observed. For example, in the NOD/SCID mouse model infected with an EV71 clinical isolate (gt B5), EV71 was predominantly muscle tropic, with severe atrophy and inflammation in the paralyzed hindlimb muscle. In contrast, in the stat-1 KO and the hybrid mouse models, EV71 behaved neurotropic with VP1 signals in both brain and spinal cord [4,5]. In the stat-1 KO model, VP1 protein was often enriched in the Purkinje layer of cerebellar cortex, pons, brain stem, and spinal cord. IBA-1+ microglia cells were found to be amplified, indicating a high degree of neuronal injury. In the hybrid mouse model, Nissl staining of spinal cord sections revealed abnormal neurons with extensive vaccuoles. Unlike the NOD/SCID model, neither VP1 signal nor inflammation was ever detected in the paralyzed muscle in stat-1 KO or hybrid mouse models. Since stat-1 is an upstream transcription factor important for interferon signaling, stat-1 or interferon deficient CNS appeared to favor neurotropic EV71. By contrast, limb muscles deficient in T and B cells appeared to favor muscle-tropic EV71.
In human clinical cases, since EV71 infection in Europe and Asia-Pacific had different clinical features, the difference in their respective ethnic (and immunogenetic) backgrounds (Caucasian vs. Asian) could be responsible for their different disease manifestations [6,76,86]. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) is an important regulator of T-cell cytotoxicity and tolerance. The polymorphism of CTLA-4 was found to be associated with encephalitis in EV71-infected children [87]. Other genetic polymorphisms, such as human leukocyte antigen-A33 (HLA-A33) [88], tumor necrosis factor-α (TNF-α), and interferon-α receptor 1 (IFNAR1) [89,90], were also found to be associated with disease severity in EV71 patients. In summary, both viral and host factors are important for EV71 immunopathogenesis.

5. Therapy

EV71 vaccination should be an effective way to protect children from infection. While inactivated whole virus of EV71 appears to be a good vaccine candidate [91,92,93,94], it is unclear if it can be used for all age groups of children. Therapeutics against EV71 remains an urgent need. We summarized here in Table 4 a list of candidate therapeutics, which had been tested in patients or animal models. We categorized these candidate compounds into four different groups according to their approaches.
Group 1 relied on passive immunization with anti-EV71 neutralizing sera raised against recombinant VP1 protein, virus-like particles (VLP), formaldehyde-inactivated whole virus, and IVIG from human source [ref cited in Table 4]. Although IVIG were used in clinical practice [17], the possibility of antibody-dependent enhancement of EV71 must be seriously considered [19,20,21]. Another important issue is whether these immune sera or antibodies can efficiently and broadly cross protect against EV71 of different genotypes. Mouse monoclonal antibodies (mAb) need to be humanized and re-tested in animal models in the future. Immune escape variants could be selected during mAb treatment.
Group 2 includes immune modulators, such as interferon (IFN-α) or TLR agonists. Pre-treatment with Poly (I:C) or co-treatment with mouse IFN and EV71, can reduce the death rate in EV71-infected mice [45]. However, some of these studies in Group 2 are prophylactic rather than therapeutic. Oral intake of GS-9620 (a TLR7 agonist) inhibited viral replication and increased the survival rate of ICR mice infected with a mouse-adapted strain MP10 [95]. In clinical trials, IFN-α can decrease the fever and viral load in mild HFMD patients [72,96]. Altogether, activation of IFN signaling could be a potential therapy for EV71 infection.
Group 3 includes anti-inflammation treatments, such as anti-IL6 Ab, and complement inhibitors [38,97]. Although compounds in Group 3 may not have any direct antiviral effect, they can help reduce inflammatory injury by excessive cytokines.
Group 4 includes various compounds, whose mechanisms either remain unclear at present, or do not belong to the above Group 1–3 [22,98,99,100,101]. For example, Milrinone is supposed to help maintain the level of catecholamine [22]. As a side note, it is worth mentioning that disinfectants against EV71 have also been investigated. While disinfectants have no therapeutic value, solutions of chlorine dioxide (ClO2) [102] and methylene blue (photosensitizer) [103] can inactivate EV71.

6. Conclusions

In 2018, there are many issues that need to be solved in the modeling of EV71 infection and pathogenesis. First, while the immune deficient NOD/SCID mice offer an efficient model for oral infection with EV71 clinical isolates, one remaining challenge is to establish an oral infection system in an immune-competent mouse model. Second, another mystery is the requirement of a neonatal age for productive EV71 infection and pathogenesis. It is widely speculated that some kind of age-related immune maturation could confer the resistance to pediatric infections, such as EV71. However, if so, the exact nature of such an age-dependent arm of the immune system remains elusive. It cannot be excluded that a putative EV71 receptor could be expressed in muscle or nerve only transiently at the neonatal age, but rapidly turned off at an older age during mouse development. Third, there is an urgent need for FDA-approved antivirals against the frequent EV71 epidemics in Asia and worldwide. Lessons that we learned from EV71 should be useful for other picornaviruses closely related to EV71, such as the most recent D68 virus that emerged in North America a few years ago.


The authors were supported by Institute of Biomedical Sciences, Academia Sinica and the EID Program, Ministry of Science and Technology, Taiwan (MOST 106-2320-B-001- 010, MOST 106-0210-01-15-02, MOST 107-2321-B-001-028, and MOST 107-0210-01-19-01).


We thank the collaborations from Ya-Yen Yu, Chi-Yung Lin, and Jen-Shiou Lin at Changhua Christian Hospital, Changhua, Taiwan.

Conflicts of Interest

We declare no competing financial interests.


  1. Schmidt, N.J.; Lennette, E.H.; Ho, H.H. An apparently new enterovirus isolated from patients with disease of the central nervous system. J. Infect. Dis. 1974, 129, 304–309. [Google Scholar] [CrossRef] [PubMed]
  2. Brown, B.A.; Pallansch, M.A. Complete nucleotide sequence of enterovirus 71 is distinct from poliovirus. Virus Res. 1995, 39, 195–205. [Google Scholar] [CrossRef]
  3. Cox, J.A.; Hiscox, J.A.; Solomon, T.; Ooi, M.H.; Ng, L.F.P. Immunopathogenesis and virus-host interactions of enterovirus 71 in patients with hand, foot and mouth disease. Front. Microbiol. 2017, 8, 2249. [Google Scholar] [CrossRef] [PubMed]
  4. Liao, C.C.; Liou, A.T.; Chang, Y.S.; Wu, S.Y.; Chang, C.S.; Lee, C.K.; Kung, J.T.; Tu, P.H.; Yu, Y.Y.; Lin, C.Y.; et al. Immunodeficient mouse models with different disease profiles by in vivo infection with the same clinical isolate of enterovirus 71. J. Virol. 2014, 88, 12485–12499. [Google Scholar] [CrossRef] [PubMed]
  5. Liou, A.-T.; Wu, S.-Y.; Liao, C.-C.; Chang, Y.-S.; Chang, C.-S.; Shih, C. A new animal model containing human SCARB2 and lacking stat-1 is highly susceptible to EV71. Sci. Rep. 2016, 6, 31151. [Google Scholar] [CrossRef] [PubMed][Green Version]
  6. Ho, M.; Chen, E.R.; Hsu, K.H.; Twu, S.J.; Chen, K.T.; Tsai, S.F.; Wang, J.R.; Shih, S.R. An epidemic of enterovirus 71 infection in Taiwan. N. Engl. J. Med. 1999, 341, 929–935. [Google Scholar] [CrossRef] [PubMed]
  7. Chang, L.-Y.; Huang, L.-M.; Gau, S.S.-F.; Wu, Y.-Y.; Hsia, S.-H.; Fan, T.-Y.; Lin, K.-L.; Huang, Y.-C.; Lu, C.-Y.; Lin, T.-Y. Neurodevelopment and cognition in children after enterovirus 71 infection. N. Engl. J. Med. 2007, 356, 1226–1231. [Google Scholar] [CrossRef] [PubMed]
  8. Wu, J.-M.; Wang, J.-N.; Tsai, Y.-C.; Liu, C.-C.; Huang, C.-C.; Chen, Y.-J.; Yeh, T.-F. Cardiopulmonary manifestations of fulminant enterovirus 71 infection. Pediatrics 2002, 109, e26. [Google Scholar] [CrossRef] [PubMed]
  9. Shimizu, H.; Utama, A.; Onnimala, N.; Li, C.; Zhang, L.-B.; Ma, Y.-J.; Pongsuwanna, Y.; Miyamura, T. Molecular epidemiology of enterovirus 71 infection in the western pacific region. Pediatr. Int. 2004, 46, 231–235. [Google Scholar] [CrossRef] [PubMed]
  10. Mizuta, K.; Aoki, Y.; Matoba, Y.; Yahagi, K.; Itagaki, T.; Katsushima, F.; Katsushima, Y.; Ito, S.; Hongo, S.; Matsuzaki, Y. Molecular epidemiology of enterovirus 71 strains isolated from children in Yamagata, Japan, between 1990 and 2013. J. Med. Microbiol. 2014, 63, 1356–1362. [Google Scholar] [CrossRef] [PubMed][Green Version]
  11. AbuBakar, S.; Chee, H.Y.; Al-Kobaisi, M.F.; Xiaoshan, J.; Chua, K.B.; Lam, S.K. Identification of enterovirus 71 isolates from an outbreak of hand, foot and mouth disease (HFMD) with fatal cases of encephalomyelitis in malaysia. Virus Res. 1999, 61, 1–9. [Google Scholar] [CrossRef]
  12. Wang, Y.; Feng, Z.; Yang, Y.; Self, S.; Gao, Y.; Longini, I.M.; Wakefield, J.; Zhang, J.; Wang, L.; Chen, X.; et al. Hand, foot, and mouth disease in china: Patterns of spread and transmissibility. Epidemiology 2011, 22, 781–792. [Google Scholar] [CrossRef] [PubMed]
  13. Fischer, T.K.; Nielsen, A.Y.; Sydenham, T.V.; Andersen, P.H.; Andersen, B.; Midgley, S.E. Emergence of enterovirus 71 C4a in Denmark, 2009 to 2013. Eurosurveillance 2014, 19, 20911. [Google Scholar] [CrossRef] [PubMed][Green Version]
  14. Medici, M.C.; Tummolo, F.; Arcangeletti, M.C.; De Conto, F.; Chezzi, C.; Dodi, I.; Calderaro, A. A cluster of enterovirus 71 subgenogroup C2 in a nursery school, Italy, 2014. New Microbiol. 2016, 39, 295–298. [Google Scholar] [PubMed]
  15. Akhmadishina, L.V.; Eremeeva, T.P.; Trotsenko, O.E.; Ivanova, O.E.; Mikhailov, M.I.; Lukashev, A.N. Seroepidemiology and molecular epidemiology of enterovirus 71 in Russia. PLoS ONE 2014, 9, e97404. [Google Scholar] [CrossRef] [PubMed]
  16. Zander, A.; Britton, P.N.; Navin, T.; Horsley, E.; Tobin, S.; McAnulty, J.M. An outbreak of enterovirus 71 in metropolitan Sydney: Enhanced surveillance and lessons learnt. Med. J. Aust. 2014, 201, 663–666. [Google Scholar] [CrossRef] [PubMed]
  17. Wang, S.M.; Lei, H.Y.; Huang, M.C.; Su, L.Y.; Lin, H.C.; Yu, C.K.; Wang, J.L.; Liu, C.C. Modulation of cytokine production by intravenous immunoglobulin in patients with enterovirus 71-associated brainstem encephalitis. J. Clin. Virol. 2006, 37, 47–52. [Google Scholar] [CrossRef] [PubMed]
  18. Cao, R.Y.; Dong, D.Y.; Liu, R.J.; Han, J.F.; Wang, G.C.; Zhao, H.; Li, X.F.; Deng, Y.Q.; Zhu, S.Y.; Wang, X.Y.; et al. Human igg subclasses against enterovirus type 71: Neutralization versus antibody dependent enhancement of infection. PLoS ONE 2013, 8, e64024. [Google Scholar] [CrossRef] [PubMed]
  19. Wang, S.M.; Chen, I.C.; Su, L.Y.; Huang, K.J.; Lei, H.Y.; Liu, C.C. Enterovirus 71 infection of monocytes with antibody-dependent enhancement. Clin. Vaccine Immunol. 2010, 17, 1517–1523. [Google Scholar] [CrossRef] [PubMed]
  20. Han, J.F.; Cao, R.Y.; Deng, Y.Q.; Tian, X.; Jiang, T.; Qin, E.D.; Qin, C.F. Antibody dependent enhancement infection of enterovirus 71 in vitro and in vivo. Virol. J. 2011, 8, 106. [Google Scholar] [CrossRef] [PubMed]
  21. Chen, I.C.; Wang, S.-M.; Yu, C.-K.; Liu, C.-C. Subneutralizing antibodies to enterovirus 71 induce antibody-dependent enhancement of infection in newborn mice. Med. Microbiol. Immunol. 2013, 202, 259–265. [Google Scholar] [CrossRef] [PubMed]
  22. Wang, S.M.; Lei, H.Y.; Huang, M.C.; Wu, J.M.; Chen, C.T.; Wang, J.N.; Wang, J.R.; Liu, C.C. Therapeutic efficacy of milrinone in the management of enterovirus 71-induced pulmonary edema. Pediatr. Pulmonol. 2005, 39, 219–223. [Google Scholar] [CrossRef] [PubMed]
  23. Han, J.F.; Cao, R.Y.; Tian, X.; Yu, M.; Qin, E.D.; Qin, C.F. Producing infectious enterovirus type 71 in a rapid strategy. Virol. J. 2010, 7, 116. [Google Scholar] [CrossRef] [PubMed][Green Version]
  24. Yu, P.; Bao, L.; Xu, L.; Li, F.; Lv, Q.; Deng, W.; Xu, Y.; Qin, C. Neurotropism in vitro and mouse models of severe and mild infection with clinical strains of enterovirus 71. Viruses 2017, 9, 351. [Google Scholar] [CrossRef] [PubMed]
  25. Wang, C.; Ji, L.; Yuan, X.; Jin, Y.; Cardona, C.J.; Xing, Z. Differential regulation of tlr signaling on the induction of antiviral interferons in human intestinal epithelial cells infected with enterovirus 71. PLoS ONE 2016, 11, e0152177. [Google Scholar] [CrossRef] [PubMed]
  26. Lui, Y.L.E.; Timms, P.; Hafner, L.M.; Tan, T.L.; Tan, K.H.; Tan, E.L. Characterisation of enterovirus 71 replication kinetics in human colorectal cell line, HT29. SpringerPlus 2013, 2, 267. [Google Scholar] [CrossRef] [PubMed][Green Version]
  27. Wang, Y.F.; Chou, C.T.; Lei, H.Y.; Liu, C.C.; Wang, S.M.; Yan, J.J.; Su, I.J.; Wang, J.R.; Yeh, T.M.; Chen, S.H.; et al. A mouse-adapted enterovirus 71 strain causes neurological disease in mice after oral infection. J. Virol. 2004, 78, 7916–7924. [Google Scholar] [CrossRef] [PubMed]
  28. Xing, Z.; Huang, H.-I.; Chio, C.-C.; Lin, J.-Y. Inhibition of EV71 by curcumin in intestinal epithelial cells. PLoS ONE 2018, 13, e0191617. [Google Scholar]
  29. Ang, L.Y.E.; Too, H.K.I.; Tan, E.L.; Chow, T.-K.V.; Shek, P.-C.L.; Tham, E.; Alonso, S. Antiviral activity of lactobacillus reuteri protectis against coxsackievirus A and enterovirus 71 infection in human skeletal muscle and colon cell lines. Virol. J. 2016, 13, 111. [Google Scholar] [CrossRef] [PubMed]
  30. Liu, Y.; Zheng, Z.; Shu, B.; Meng, J.; Zhang, Y.; Zheng, C.; Ke, X.; Gong, P.; Hu, Q.; Wang, H.; et al. Sumo modification stabilizes enterovirus 71 polymerase 3D to facilitate viral replication. J. Virol. 2016, 90, 10472–10485. [Google Scholar] [CrossRef] [PubMed]
  31. Du, X.; Wang, H.; Xu, F.; Huang, Y.; Liu, Z.; Liu, T.E. Enterovirus 71 induces apoptosis of SH-SY5Y human neuroblastoma cells through stimulation of endogenous microRNA let-7b expression. Mol. Med. Rep. 2015, 12, 953–959. [Google Scholar] [CrossRef] [PubMed][Green Version]
  32. Xu, L.J.; Jiang, T.; Zhang, F.J.; Han, J.F.; Liu, J.; Zhao, H.; Li, X.F.; Liu, R.J.; Deng, Y.Q.; Wu, X.Y.; et al. Global transcriptomic analysis of human neuroblastoma cells in response to enterovirus type 71 infection. PLoS ONE 2013, 8, e65948. [Google Scholar] [CrossRef] [PubMed]
  33. Too, I.H.K.; Yeo, H.; Sessions, O.M.; Yan, B.; Libau, E.A.; Howe, J.L.C.; Lim, Z.Q.; Suku-Maran, S.; Ong, W.-Y.; Chua, K.B.; et al. Enterovirus 71 infection of motor neuron-like NSC-34 cells undergoes a non-lytic exit pathway. Sci. Rep. 2016, 6, 36983. [Google Scholar] [CrossRef] [PubMed][Green Version]
  34. Shih, S.-R.; Weng, K.-F.; Stollar, V.; Li, M.-L. Viral protein synthesis is required for enterovirus 71 to induce apoptosis in human glioblastoma cells. J. Neurovirol. 2008, 14, 53–61. [Google Scholar] [CrossRef] [PubMed]
  35. Tse, H.; Victorio, C.B.L.; Xu, Y.; Ng, Q.; Chow, V.T.K.; Chua, K.B. Phenotypic and genotypic characteristics of novel mouse cell line (NIH/3T3)-adapted human enterovirus 71 strains (EV71:TLLm and EV71:TLLmv). PLoS ONE 2014, 9, e92719. [Google Scholar]
  36. Wang, B.; Xi, X.; Lei, X.; Zhang, X.; Cui, S.; Wang, J.; Jin, Q.; Zhao, Z. Enterovirus 71 protease 2Apro targets MAVS to inhibit anti-viral type I interferon responses. PLoS Pathog. 2013, 9, e1003231. [Google Scholar] [CrossRef] [PubMed]
  37. Wang, W.; Xiao, F.; Wan, P.; Pan, P.; Zhang, Y.; Liu, F.; Wu, K.; Liu, Y.; Wu, J. Ev71 3d protein binds with nlrp3 and enhances the assembly of inflammasome complex. PLoS Pathog. 2017, 13, e1006123. [Google Scholar] [CrossRef] [PubMed]
  38. Khong, W.X.; Foo, D.G.; Trasti, S.L.; Tan, E.L.; Alonso, S. Sustained high levels of interleukin-6 contribute to the pathogenesis of enterovirus 71 in a neonate mouse model. J. Virol. 2011, 85, 3067–3076. [Google Scholar] [CrossRef] [PubMed]
  39. Chang, G.H.; Lin, L.; Luo, Y.J.; Cai, L.J.; Wu, X.Y.; Xu, H.M.; Zhu, Q.Y. Sequence analysis of six enterovirus 71 strains with different virulences in humans. Virus Res. 2010, 151, 66–73. [Google Scholar] [CrossRef] [PubMed]
  40. Zaini, Z.; McMinn, P. A single mutation in capsid protein VP1 (Q145E) of a genogroup C4 strain of human enterovirus 71 generates a mouse-virulent phenotype. J. Gen. Virol. 2012, 93, 1935–1940. [Google Scholar] [CrossRef] [PubMed][Green Version]
  41. Chua, B.H.; Phuektes, P.; Sanders, S.A.; Nicholls, P.K.; McMinn, P.C. The molecular basis of mouse adaptation by human enterovirus 71. J. Gen. Virol. 2008, 89, 1622–1632. [Google Scholar] [CrossRef] [PubMed][Green Version]
  42. Chen, Y.C.; Yu, C.-K.; Wang, Y.-F.; Liu, C.-C.; Su, I.-J.; Lei, H.-Y. A murine oral enterovirus 71 infection model with central nervous system involvement. J. Gen. Virol. 2004, 85, 69–77. [Google Scholar] [CrossRef] [PubMed][Green Version]
  43. Wang, W.; Duo, J.; Liu, J.; Ma, C.; Zhang, L.; Wei, Q.; Qin, C. A mouse muscle-adapted enterovirus 71 strain with increased virulence in mice. Microbes Infect. 2011, 13, 862–870. [Google Scholar] [CrossRef] [PubMed]
  44. Lin, Y.W.; Chang, K.C.; Kao, C.M.; Chang, S.P.; Tung, Y.Y.; Chen, S.H. Lymphocyte and antibody responses reduce enterovirus 71 lethality in mice by decreasing tissue viral loads. J. Virol. 2009, 83, 6477–6483. [Google Scholar] [CrossRef] [PubMed]
  45. Liu, M.L.; Lee, Y.-P.; Liu, C.-C.; Yeh, T.-M.; Wang, S.-M.; Chen, S.-H.; Wang, Y.-F.; Su, I.-J.; Lei, H.-Y.; Wang, J.-R.; et al. Type I interferons protect mice against enterovirus 71 infection. J. Gen. Virol. 2005, 86, 3263–3269. [Google Scholar] [CrossRef] [PubMed][Green Version]
  46. Li, Z.H.; Li, C.M.; Ling, P.; Shen, F.H.; Chen, S.H.; Liu, C.C.; Yu, C.K.; Chen, S.H. Ribavirin reduces mortality in enterovirus 71-infected mice by decreasing viral replication. J. Infect. Dis. 2008, 197, 854–857. [Google Scholar] [CrossRef] [PubMed]
  47. Ong, K.C.; Devi, S.; Cardosa, M.J.; Wong, K.T. Formaldehyde-inactivated whole-virus vaccine protects a murine model of enterovirus 71 encephalomyelitis against disease. J. Virol. 2010, 84, 661–665. [Google Scholar] [CrossRef] [PubMed]
  48. Ong, K.C.; Badmanathan, M.; Devi, S.; Leong, K.L.; Cardosa, M.J.; Wong, K.T. Pathologic characterization of a murine model of human enterovirus 71 encephalomyelitis. J. Neuropathol. Exp. Neurol. 2008, 67, 532–542. [Google Scholar] [CrossRef] [PubMed]
  49. Shen, F.H.; Tsai, C.C.; Wang, L.C.; Chang, K.C.; Tung, Y.Y.; Su, I.J.; Chen, S.H. Enterovirus 71 infection increases expression of interferon-gamma-inducible protein 10 which protects mice by reducing viral burden in multiple tissues. J. Gen. Virol. 2013, 94, 1019–1027. [Google Scholar] [CrossRef] [PubMed]
  50. Liu, J.; Dong, W.; Quan, X.; Ma, C.; Qin, C.; Zhang, L. Transgenic expression of human p-selectin glycoprotein ligand-1 is not sufficient for enterovirus 71 infection in mice. Arch. Virol. 2011, 157, 539–543. [Google Scholar] [CrossRef] [PubMed]
  51. Fujii, K.; Nagata, N.; Sato, Y.; Ong, K.C.; Wong, K.T.; Yamayoshi, S.; Shimanuki, M.; Shitara, H.; Taya, C.; Koike, S. Transgenic mouse model for the study of enterovirus 71 neuropathogenesis. Proc. Natl. Acad. Sci. USA 2013, 110, 14753–14758. [Google Scholar] [CrossRef] [PubMed][Green Version]
  52. Lin, Y.-W.; Yu, S.-L.; Shao, H.-Y.; Lin, H.-Y.; Liu, C.-C.; Hsiao, K.-N.; Chitra, E.; Tsou, Y.-L.; Chang, H.-W.; Sia, C.; et al. Human SCARB2 transgenic mice as an infectious animal model for enterovirus 71. PLoS ONE 2013, 8, e57591. [Google Scholar] [CrossRef] [PubMed]
  53. Khong, W.X.; Yan, B.; Yeo, H.; Tan, E.L.; Lee, J.J.; Ng, J.K.; Chow, V.T.; Alonso, S. A non-mouse-adapted enterovirus 71 (EV71) strain exhibits neurotropism, causing neurological manifestations in a novel mouse model of EV71 infection. J. Virol. 2012, 86, 2121–2131. [Google Scholar] [CrossRef] [PubMed]
  54. Caine, E.A.; Partidos, C.D.; Santangelo, J.D.; Osorio, J.E. Adaptation of enterovirus 71 to adult interferon deficient mice. PLoS ONE 2013, 8, e59501. [Google Scholar] [CrossRef] [PubMed]
  55. Arita, M.; Ami, Y.; Wakita, T.; Shimizu, H. Cooperative effect of the attenuation determinants derived from poliovirus sabin 1 strain is essential for attenuation of enterovirus 71 in the NOD/SCID mouse infection model. J. Virol. 2008, 82, 1787–1797. [Google Scholar] [CrossRef] [PubMed]
  56. Lyu, K.; Wang, G.C.; He, Y.L.; Han, J.F.; Ye, Q.; Qin, C.F.; Chen, R. Crystal structures of enterovirus 71 (EV71) recombinant virus particles provide insights into vaccine design. J. Biol. Chem. 2015, 290, 3198–3208. [Google Scholar] [CrossRef] [PubMed]
  57. Ooi, M.H.; Wong, S.C.; Lewthwaite, P.; Cardosa, M.J.; Solomon, T. Clinical features, diagnosis, and management of enterovirus 71. Lancet Neurol. 2010, 9, 1097–1105. [Google Scholar] [CrossRef]
  58. Chang, L.Y.; King, C.C.; Hsu, K.H.; Ning, H.C.; Tsao, K.C.; Li, C.C.; Huang, Y.C.; Shih, S.R.; Chiou, S.T.; Chen, P.Y.; et al. Risk factors of enterovirus 71 infection and associated hand, foot, and mouth disease/herpangina in children during an epidemic in taiwan. Pediatrics 2002, 109, e88. [Google Scholar] [CrossRef] [PubMed]
  59. Nishimura, Y.; Shimojima, M.; Tano, Y.; Miyamura, T.; Wakita, T.; Shimizu, H. Human p-selectin glycoprotein ligand-1 is a functional receptor for enterovirus 71. Nat. Med. 2009, 15, 794–797. [Google Scholar] [CrossRef] [PubMed]
  60. Yamayoshi, S.; Yamashita, Y.; Li, J.; Hanagata, N.; Minowa, T.; Takemura, T.; Koike, S. Scavenger receptor B2 is a cellular receptor for enterovirus 71. Nat. Med. 2009, 15, 798–801. [Google Scholar] [CrossRef] [PubMed]
  61. Yang, S.L.; Chou, Y.T.; Wu, C.N.; Ho, M.S. Annexin ii binds to capsid protein vp1 of enterovirus 71 and enhances viral infectivity. J. Virol. 2011, 85, 11809–11820. [Google Scholar] [CrossRef] [PubMed]
  62. Su, P.Y.; Wang, Y.F.; Huang, S.W.; Lo, Y.C.; Wang, Y.H.; Wu, S.R.; Shieh, D.B.; Chen, S.H.; Wang, J.R.; Lai, M.D.; et al. Cell surface nucleolin facilitates enterovirus 71 binding and infection. J. Virol. 2015, 89, 4527–4538. [Google Scholar] [CrossRef] [PubMed]
  63. Tan, C.W.; Poh, C.L.; Sam, I.C.; Chan, Y.F. Enterovirus 71 uses cell surface heparan sulfate glycosaminoglycan as an attachment receptor. J. Virol. 2013, 87, 611–620. [Google Scholar] [CrossRef] [PubMed]
  64. Ren, X.X.; Ma, L.; Liu, Q.W.; Li, C.; Huang, Z.; Wu, L.; Xiong, S.D.; Wang, J.H.; Wang, H.B. The molecule of DC-SIGN captures enterovirus 71 and confers dendritic cell-mediated viral trans-infection. Virol. J. 2014, 11, 47. [Google Scholar] [CrossRef] [PubMed][Green Version]
  65. Fukuhara, M.; Iwami, S.; Sato, K.; Nishimura, Y.; Shimizu, H.; Aihara, K.; Koyanagi, Y. Quantification of the dynamics of enterovirus 71 infection by experimental-mathematical investigation. J. Virol. 2013, 87, 701–705. [Google Scholar] [CrossRef] [PubMed]
  66. Yu, P.; Gao, Z.; Zong, Y.; Bao, L.; Xu, L.; Deng, W.; Li, F.; Lv, Q.; Gao, Z.; Xu, Y.; et al. Histopathological features and distribution of EV71 antigens and SCARB2 in human fatal cases and a mouse model of enterovirus 71 infection. Virus Res. 2014, 189, 121–132. [Google Scholar] [CrossRef] [PubMed]
  67. Chen, C.S.; Yao, Y.C.; Lin, S.C.; Lee, Y.P.; Wang, Y.F.; Wang, J.R.; Liu, C.C.; Lei, H.Y.; Yu, C.K. Retrograde axonal transport: A major transmission route of enterovirus 71 in mice. J. Virol. 2007, 81, 8996–9003. [Google Scholar] [CrossRef] [PubMed]
  68. Wong, K.T.; Munisamy, B.; Ong, K.C.; Kojima, H.; Noriyo, N.; Chua, K.B.; Ong, B.B.; Nagashima, K. The distribution of inflammation and virus in human enterovirus 71 encephalomyelitis suggests possible viral spread by neural pathways. J. Neuropathol. Exp. Neurol. 2008, 67, 162–169. [Google Scholar] [CrossRef] [PubMed]
  69. Ren, R.; Racaniello, V.R. Poliovirus spreads from muscle to the central nervous system by neural pathways. J. Infect. Dis. 1992, 166, 747–752. [Google Scholar] [CrossRef] [PubMed]
  70. Zhang, Y.; Li, J.; Li, Q. Immune evasion of enteroviruses under innate immune monitoring. Front. Microbiol. 2018, 9, 1866. [Google Scholar] [CrossRef] [PubMed]
  71. Sun, J.; Ennis, J.; Turner, J.D.; Chu, J.J. Single dose of an adenovirus vectored mouse interferon-alpha protects mice from lethal EV71 challenge. Antivir. Res. 2016, 134, 207–215. [Google Scholar] [CrossRef] [PubMed]
  72. Lin, H.; Huang, L.; Zhou, J.; Lin, K.; Wang, H.; Xue, X.; Xia, C. Efficacy and safety of interferon-α2b spray in the treatment of hand, foot, and mouth disease: A multicenter, randomized, double-blind trial. Arch. Virol. 2016, 161, 3073–3080. [Google Scholar] [CrossRef] [PubMed]
  73. Meng, G.; Li, M.; Li, Y.; Wang, X.; Chen, Q.; Wei, H.J.C.J.C.E.P. Severe hand-foot-mouth disease: A report of 3 autopsied cases. Chin. J. Clin. Exp. Pathol. 2011, 27, 48–51. [Google Scholar]
  74. Wang, S.M.; Lei, H.Y.; Yu, C.K.; Wang, J.R.; Su, I.J.; Liu, C.C. Acute chemokine response in the blood and cerebrospinal fluid of children with enterovirus 71-associated brainstem encephalitis. J. Infect. Dis. 2008, 198, 1002–1006. [Google Scholar] [CrossRef] [PubMed]
  75. Lin, Y.L.; Chow, Y.H.; Huang, L.M.; Hsieh, S.M.; Cheng, P.Y.; Hu, K.C.; Chiang, B.L. A CpG-adjuvanted intranasal enterovirus 71 vaccine elicits mucosal and systemic immune responses and protects human SCARB2-transgenic mice against lethal challenge. Sci. Rep. 2018, 8, 10713. [Google Scholar] [CrossRef] [PubMed]
  76. Chumakov, M.; Voroshilova, M.; Shindarov, L.; Lavrova, I.; Gracheva, L.; Koroleva, G.; Vasilenko, S.; Brodvarova, I.; Nikolova, M.; Gyurova, S.; et al. Enterovirus 71 isolated from cases of epidemic poliomyelitis-like disease in Bulgaria. Arch. Virol. 1979, 60, 329–340. [Google Scholar] [CrossRef] [PubMed]
  77. Nagy, G.; Takatsy, S.; Kukan, E.; Mihaly, I.; Domok, I. Virological diagnosis of enterovirus type 71 infections: Experiences gained during an epidemic of acute CNS diseases in hungary in 1978. Arch. Virol. 1982, 71, 217–227. [Google Scholar] [CrossRef] [PubMed]
  78. Shih, S.R.; Ho, M.S.; Lin, K.H.; Wu, S.L.; Chen, Y.T.; Wu, C.N.; Lin, T.Y.; Chang, L.Y.; Tsao, K.C.; Ning, H.C.; et al. Genetic analysis of enterovirus 71 isolated from fatal and non-fatal cases of hand, foot and mouth disease during an epidemic in taiwan, 1998. Virus Res. 2000, 68, 127–136. [Google Scholar] [CrossRef]
  79. Yan, J.J.; Su, I.J.; Chen, P.F.; Liu, C.C.; Yu, C.K.; Wang, J.R. Complete genome analysis of enterovirus 71 isolated from an outbreak in taiwan and rapid identification of enterovirus 71 and coxsackievirus A16 by RT-PCR. J. Med. Virol. 2001, 65, 331–339. [Google Scholar] [CrossRef] [PubMed]
  80. Li, R.; Zou, Q.; Chen, L.; Zhang, H.; Wang, Y. Molecular analysis of virulent determinants of enterovirus 71. PLoS ONE 2011, 6, e26237. [Google Scholar] [CrossRef] [PubMed]
  81. Huang, S.W.; Wang, Y.F.; Yu, C.K.; Su, I.J.; Wang, J.R. Mutations in VP2 and VP1 capsid proteins increase infectivity and mouse lethality of enterovirus 71 by virus binding and RNA accumulation enhancement. Virology 2012, 422, 132–143. [Google Scholar] [CrossRef] [PubMed]
  82. Yeh, M.T.; Wang, S.W.; Yu, C.K.; Lin, K.H.; Lei, H.Y.; Su, I.J.; Wang, J.R. A single nucleotide in stem loop II of 5′-untranslated region contributes to virulence of enterovirus 71 in mice. PLoS ONE 2011, 6, e27082. [Google Scholar] [CrossRef] [PubMed]
  83. Cordey, S.; Petty, T.J.; Schibler, M.; Martinez, Y.; Gerlach, D.; van Belle, S.; Turin, L.; Zdobnov, E.; Kaiser, L.; Tapparel, C. Identification of site-specific adaptations conferring increased neural cell tropism during human enterovirus 71 infection. PLoS Pathog. 2012, 8, e1002826. [Google Scholar] [CrossRef] [PubMed]
  84. Kobayashi, K.; Sudaka, Y.; Takashino, A.; Imura, A.; Fujii, K.; Koike, S. Amino acid variation at VP1-145 of enterovirus 71 determines attachment receptor usage and neurovirulence in human scavenger receptor B2 transgenic mice. J. Virol. 2018. [Google Scholar] [CrossRef] [PubMed]
  85. Tseligka, E.D.; Sobo, K.; Stoppini, L.; Cagno, V.; Abdul, F.; Piuz, I.; Meylan, P.; Huang, S.; Constant, S.; Tapparel, C. A VP1 mutation acquired during an enterovirus 71 disseminated infection confers heparan sulfate binding ability and modulates ex vivo tropism. PLoS Pathog. 2018, 14, e1007190. [Google Scholar] [CrossRef] [PubMed]
  86. McMinn, P.C. An overview of the evolution of enterovirus 71 and its clinical and public health significance. FEMS Microbiol. Rev. 2002, 26, 91–107. [Google Scholar] [CrossRef] [PubMed][Green Version]
  87. Yang, K.D.; Yang, M.Y.; Li, C.C.; Lin, S.F.; Chong, M.C.; Wang, C.L.; Chen, R.F.; Lin, T.Y. Altered cellular but not humoral reactions in children with complicated enterovirus 71 infections in Taiwan. J. Infect. Dis. 2001, 183, 850–856. [Google Scholar] [CrossRef] [PubMed]
  88. Chang, L.Y.; Chang, I.S.; Chen, W.J.; Huang, Y.C.; Chen, G.W.; Shih, S.R.; Juang, J.L.; Shih, H.M.; Hsiung, C.A.; Lin, T.Y.; et al. HLA-A33 is associated with susceptibility to enterovirus 71 infection. Pediatrics 2008, 122, 1271–1276. [Google Scholar] [CrossRef] [PubMed]
  89. Li, J.A.; Chen, Z.B.; Lv, T.G.; Han, Z.L.; Liu, P.P. Impact of endothelial nitric oxide synthase gene polymorphism on severity of enterovirus 71-infection in Chinese children. Clin. Biochem. 2013, 46, 1842–1847. [Google Scholar] [CrossRef] [PubMed]
  90. Zou, R.; Zhang, G.; Li, S.; Wang, W.; Yuan, J.; Li, J.; Wang, Y.; Lin, Y.; Deng, Y.; Zhou, B.; et al. A functional polymorphism in IFNAR1 gene is associated with susceptibility and severity of HFMD with EV71 infection. Sci. Rep. 2015, 5, 18541. [Google Scholar] [CrossRef] [PubMed]
  91. Zhu, F.; Xu, W.; Xia, J.; Liang, Z.; Liu, Y.; Zhang, X.; Tan, X.; Wang, L.; Mao, Q.; Wu, J.; et al. Efficacy, safety, and immunogenicity of an enterovirus 71 vaccine in china. N. Engl. J. Med. 2014, 370, 818–828. [Google Scholar] [CrossRef] [PubMed]
  92. Li, R.; Liu, L.; Mo, Z.; Wang, X.; Xia, J.; Liang, Z.; Zhang, Y.; Li, Y.; Mao, Q.; Wang, J.; et al. An inactivated enterovirus 71 vaccine in healthy children. N. Engl. J. Med. 2014, 370, 829–837. [Google Scholar] [CrossRef] [PubMed]
  93. Wei, M.; Meng, F.; Wang, S.; Li, J.; Zhang, Y.; Mao, Q.; Hu, Y.; Liu, P.; Shi, N.; Tao, H.; et al. 2-year efficacy, immunogenicity, and safety of vigoo enterovirus 71 vaccine in healthy Chinese children: A randomized open-label study. J. Infect. Dis. 2017, 215, 56–63. [Google Scholar] [CrossRef] [PubMed]
  94. Yi, E.J.; Shin, Y.J.; Kim, J.H.; Kim, T.G.; Chang, S.Y. Enterovirus 71 infection and vaccines. Clin. Exp. Vaccine Res. 2017, 6, 4–14. [Google Scholar] [CrossRef] [PubMed]
  95. Zhang, Q.; Zhao, B.; Chen, X.; Song, N.; Wu, J.; Li, G.; Yu, P.; Han, Y.; Liu, J.; Qin, C. GS-9620 inhibits enterovirus 71 replication mainly through the NF-kB and PI3K-AKT signaling pathways. Antivir. Res. 2018, 153, 39–48. [Google Scholar] [CrossRef] [PubMed]
  96. Huang, X.; Zhang, X.; Wang, F.; Wei, H.; Ma, H.; Sui, M.; Lu, J.; Wang, H.; Dumler, J.S.; Sheng, G.; et al. Clinical efficacy of therapy with recombinant human interferon alpha1b in hand, foot, and mouth disease with enterovirus 71 infection. PLoS ONE 2016, 11, e0148907. [Google Scholar]
  97. Qiu, S.; Liu, N.; Jia, L.; Yang, G.; Su, W.; Li, J.; Song, L.; Yang, C.; Wang, J.; Zhang, C.; et al. A new treatment for neurogenic inflammation caused by EV71 with CR2-targeted complement inhibitor. Virol. J. 2012, 9, 285. [Google Scholar] [CrossRef] [PubMed][Green Version]
  98. Dai, W.; Wu, Y.; Bi, J.; Lu, X.; Hou, A.; Zhou, Y.; Sun, B.; Kong, W.; Barbier, J.; Cintrat, J.-C.; et al. Antiviral effects of Retro-2cycl and Retro-2.1 against Enterovirus 71 in vitro and in vivo. Antivir. Res. 2017, 144, 311–321. [Google Scholar] [CrossRef] [PubMed]
  99. Zhang, G.; Zhou, F.; Gu, B.; Ding, C.; Feng, D.; Xie, F.; Wang, J.; Zhang, C.; Cao, Q.; Deng, Y.; et al. In vitro and in vivo evaluation of ribavirin and pleconaril antiviral activity against enterovirus 71 infection. Arch. Virol. 2012, 157, 669–679. [Google Scholar] [CrossRef] [PubMed]
  100. Li, M.; Yang, X.; Guan, C.; Wen, T.; Duan, Y.; Zhang, W.; Li, X.; Wang, Y.; Zhao, Z.; Liu, S. Andrographolide sulfonate reduces mortality in enterovirus 71 infected mice by modulating immunity. Int. Immunopharmacol. 2018, 55, 142–150. [Google Scholar] [CrossRef] [PubMed]
  101. Liu, J.; Li, X.; Fan, X.; Ma, C.; Qin, C.; Zhang, L. Adoptive transfer of macrophages from adult mice reduces mortality in mice infected with human enterovirus 71. Arch. Virol. 2013, 158, 387–397. [Google Scholar] [CrossRef] [PubMed]
  102. Ma, J.W.; Huang, B.S.; Hsu, C.W.; Peng, C.W.; Cheng, M.L.; Kao, J.Y.; Way, T.D.; Yin, H.C.; Wang, S.S. Efficacy and safety evaluation of a chlorine dioxide solution. Int. J. Environ. Res. Public Health 2017, 14, 329. [Google Scholar] [CrossRef] [PubMed]
  103. Wong, T.W.; Huang, H.J.; Wang, Y.F.; Lee, Y.P.; Huang, C.C.; Yu, C.K. Methylene blue-mediated photodynamic inactivation as a novel disinfectant of enterovirus 71. J. Antimicrob. Chemother. 2010, 65, 2176–2182. [Google Scholar] [CrossRef] [PubMed][Green Version]
  104. Zhou, B.; Xu, L.; Zhu, R.; Tang, J.; Wu, Y.; Su, R.; Yin, Z.; Liu, D.; Jiang, Y.; Wen, C.; et al. A bispecific broadly neutralizing antibody against enterovirus 71 and coxsackievirus A16 with therapeutic potential. Antivir. Res. 2019, 161, 28–35. [Google Scholar] [CrossRef] [PubMed]
  105. Chang, H.-W.; Lin, Y.-W.; Ho, H.-M.; Lin, M.-H.; Liu, C.-C.; Shao, H.-Y.; Chong, P.; Sia, C.; Chow, Y.-H. Protective efficacy of VP1-specific neutralizing antibody associated with a reduction of viral load and pro-inflammatory cytokines in human SCARB2-transgenic mice. PLoS ONE 2013, 8, e69858. [Google Scholar] [CrossRef] [PubMed]
  106. Wang, K.-T.; Lin, S.-J.; Wang, H.-C.; Chen, P.-C.; Lin, J.-J.; Chiang, J.-R.; Chang, C.-L.; Shih, D.Y.-C.; Lo, C.-F.; Wang, D.-Y. Establishment of an animal challenge model as a potency assay for an inactivated enterovirus type 71 vaccine. Biologicals 2016, 44, 183–190. [Google Scholar] [CrossRef] [PubMed]
  107. Cao, R.-Y.; Han, J.-F.; Jiang, T.; Tian, X.; Yu, M.; Deng, Y.-Q.; Qin, E.D.; Qin, C.-F. In vitro and in vivo characterization of a new enterovirus type 71-specific human intravenous immunoglobulin manufactured from selected plasma donors. J. Clin. Virol. 2011, 51, 246–249. [Google Scholar] [CrossRef] [PubMed]
  108. Xu, F.; Yao, P.-P.; Xia, Y.; Qian, L.; Yang, Z.-N.; Xie, R.-H.; Sun, Y.-S.; Lu, H.-J.; Miao, Z.-P.; Li, C.; et al. Enterovirus 71 infection causes severe pulmonary lesions in gerbils, meriones unguiculatus, which can be prevented by passive immunization with specific antisera. PLoS ONE 2015, 10, e0119173. [Google Scholar] [CrossRef] [PubMed]
  109. Ho, B.-C.; Yu, I.S.; Lu, L.-F.; Rudensky, A.; Chen, H.-Y.; Tsai, C.-W.; Chang, Y.-L.; Wu, C.-T.; Chang, L.-Y.; Shih, S.-R.; et al. Inhibition of miR-146a prevents enterovirus-induced death by restoring the production of type I interferon. Nat. Commun. 2014, 5, 3344. [Google Scholar] [CrossRef] [PubMed][Green Version]
Figure 1. The genomic organization of EV71. The plus-strand RNA of EV71 genome encodes a single polyprotein precursor. Upon proteolytic processing by virus-encoded proteases 2A and 3C, this polyprotein precursor converts into several smaller mature products, including 4 structural proteins (VP1-VP4 capsid protein) and 7 non-structural proteins (2A, 2B, 2C, 3A, 3B, 3C and 3D). 3B encodes a VPg protein, which is covalently bound to the 5′ end of the RNA genome. 3D encodes RNA-dependent RNA polymerase. IRES: internal ribosome entry site. This cartoon illustration is based on gt B5 clinical isolates in Taiwan [4,5]. However, it is representative of the general genomic structure of all genotypes isolated elsewhere.
Figure 1. The genomic organization of EV71. The plus-strand RNA of EV71 genome encodes a single polyprotein precursor. Upon proteolytic processing by virus-encoded proteases 2A and 3C, this polyprotein precursor converts into several smaller mature products, including 4 structural proteins (VP1-VP4 capsid protein) and 7 non-structural proteins (2A, 2B, 2C, 3A, 3B, 3C and 3D). 3B encodes a VPg protein, which is covalently bound to the 5′ end of the RNA genome. 3D encodes RNA-dependent RNA polymerase. IRES: internal ribosome entry site. This cartoon illustration is based on gt B5 clinical isolates in Taiwan [4,5]. However, it is representative of the general genomic structure of all genotypes isolated elsewhere.
Viruses 10 00674 g001
Table 1. Summary of 16 cell lines used for EV71 in vitro infection.
Table 1. Summary of 16 cell lines used for EV71 in vitro infection.
Cell LineSpeciesTissue OriginEV71 GenotypeCPE #References
RDHumanRhabdomyosarcomaA, B, C, D+[23,24,25,26,27,28,29,30]
SK-N-SHNeuroblastomaC2, D+[24,27]
NSC-34motor neuron cell lineB2, B4 & C2[33]
HT29Humanintestinal epithelial cellB4, C+[25,26,28]
Caco-2colorectal carcinomaB, C2+[27,29]
C2BBelmature intestinal epithelial cell (derived from Caco-2)C+[28]
HeLaHumancervical carcinomaEV71:BS (Accession NO KF514878), C4+[35,36]
HEK293THumanembryonic kidneyEV71:BS (Accession NO KF514878), C4+[35,37]
THP-1Humanmonocytic cell lineC2, C4 [19,37]
human PBMC C2 [19]
VeroMonkeyAfrican green monkey kidneyA, EV71:BS (Accession NO KF514878)+[30,35]
COS-7African green monkey kidney (SV40 transformed)EV71:BS (Accession NO KF514878)+[35]
NIH/3T3Mousemouse embryonic fibroblastmouse-adapted strain (EV:TLLm)+[35]
* information not available. # CPE, cytopathic effect. Genotype D is a C4 subgenotype.
Table 2. Summary of 22 animal models used for EV71 in vivo infection.
Table 2. Summary of 22 animal models used for EV71 in vivo infection.
Mouse StrainHost Age @RouteGenotypeTiter/MousePhenotypeVirus-Replicating TissueReference
Balb/C1-day-oldi.p.B41 × 104 PFUlimb paralysis & deathintestine[38]
2-day-oldi.p./i.c.C4103 TCID50*brain, liver and intestine[39]
5-day-oldi.p.C4 (mouse adapted strain)104 TCID50limb paralysis & deathspleen, heart, liver, muscle and brain[40]
B3 (CHO cell adapted strain;
CHO-26M) (mouse adapted strain;
103 TCID50deathmuscle (CHO-26M) blood, spleen, heart, liver, muscle and brain (MP-26M)[41]
9-day-oldi.p.C4104.5 TCID50limb paralysisskeletal muscle, spinal cord, brainstem, lung, and jejunum[24]
ICR1-day-oldoralC (mouse adapted strain)106–107 PFUparalysis & skin lesionskin, intestine and spinal cord[42]
1-day-oldi.p.C4 (Fuyang-0805a)2 × 105 TCID50nonemuscles, intestines, lungs, and brain[43]
7-day-oldoralC (mouse adapted strain M2)5 × 106 PFUdeath*[44]
7-day-oldi.p.C2 (mouse adapted strain MP4)2.5 × 106 PFUdeathbrain, spinal cord, lung and muscle[21]
3-day-oldi.p.C2 (clinical isolate)4 × 106 PFUdeath*[45]
7-day-oldoralC2 (mouse adapted strain MP4)5 × 105 PFUdeath*[45]
12–14-day-oldi.p.C (mouse adapted strain M2)5 × 104–105 PFUparalysis & death*[46]
14-day-oldi.p.B3 (mouse adapted strain)100 CCID50paralysisbrain and muscle[47]
14-day- &
B3 (mouse adapted strain)105 CCID50paralysismainly in CNS[48]
C57BL/69-day-oldoralC (mouse adapted strain M2)3 × 107 PFU**[44]
C57BL/6J14-day-oldi.p.C (mouse adapted strain M2)3 × 105 PFUhunched posture, paralysis & deathbrain[49]
PSGL-1 Tg10-day-oldi.p.C4 (clinical isolate)108 TCID50no disease onsetbrain, spinal cord and skeletal muscle[50]
C4 (mouse adapted strain MP10)5 × 106 TCID50hindlimb paralysis*
hSCARB2 Tg3-week-oldi.v.C (Isehara strain)102–6 TCID50ataxia, paralysis & deathCNS[51]
i.c.A, B and C102–6 TCID50
i.p.C (Isehara strain)103–6 TCID50
oralC (Isehara strain)106–7 TCID50
pEF-1α-hSCARB21-day-olds.c.B1 × 107 PFUHFMD-like syndrome & paralysisCNS, intestine, muscle and skin[52]
7-day-olds.c.C3 × 104 PFU
AG129younger than 2-week-oldi.p.B45 × 105–107 PFUlimb paralysis & deathCNS[53]
oral106–107 PFU
AG12910-week-oldi.p.B2 (mouse adapted strain)1.3 × 105 TCID50/mLlimb paralysis & deathND[54]
G1297-day-oldi.p.B5 (clinical isolates)108 PFUlimb paralysis & deathND[4]
stat-1 KO7-day-oldi.p.B5 (clinical isolates)108 PFUlimb paralysis & deathCNS[4]
stat-1 KO
younger than 2-week-oldi.p.C2 (clinical isolates)106–108 PFU[5]
NOD/SCID3-day-oldoralB5 (clinical isolates)108 PFUhair loss, skin lesion, limb paralysis & deathmuscle and spleen[4]
7-day-oldi.p.107–108 PFU
3–4 week-oldi.v./i.c.B1 (mouse adapted strain)106.5 CCID50 skeletal muscle and heart[55]
IP10 KO14-day-oldi.p.C (mouse adapted strain M2)3 × 105 PFUThe death rate was higher than C57BL/6JND[49]
* information not available. @ The age that mice infected with EV71.
Table 3. Comparisons between human SCARB2-transgenic and wild type non-transgenic mice in EV71 infection and pathogenesis.
Table 3. Comparisons between human SCARB2-transgenic and wild type non-transgenic mice in EV71 infection and pathogenesis.
Mouse StrainsPromoterVirus Strain (Genotype)Host AgeVirus DoseInoculation Route% Earlier symptom **
(Tg vs. non-Tg)
% Limb Paralysis
(Tg vs. non-Tg)
% Death
(Tg vs. non-Tg)
pEF-1α- hSCARB2ubiquitous
E59 (B4)1-day-old3 × 104 PFUs.c.100 vs. 57.118.8 vs. 14.20 vs. 0[52]
N-2838 (B5)100 vs.7544.4 vs. 12.50 vs. 0
5476 (C2)7-day-old107 PFUs.c.Nd @100 vs. 57.1100 vs. 0
N3340 (C4)Nd @100 vs. 100100 vs. 0
pSC2- hSCARB2native promoterIsehara (C2)3-wk-old106 TCID50i.c.N/A #100 vs. 0 *[51]
i.v.N/A #89 vs. 0 *
i.p.N/A #39 vs. 0 *
oralN/A #5 vs. 0 *
@: No disease detected; #: No information available in the original paper; * combined score of ataxia, limb paralysis, and death; ** Earlier symptoms include hair loss and scurf.
Table 4. Therapeutic compounds tested in animal models and human patients.
Table 4. Therapeutic compounds tested in animal models and human patients.
Therapeutic ApproachesDrug CandidatesDrug Delivery MethodsHuman or Animal ModelHost Age at Virus InoculationVirus InoculationEV71 Clinical Isolates * or Adapted Strains #Virus GenotypeRef.
Passive immunization
bispecific anti-EV71 & CA16 Ab Bs(scFv)i.p. injection at 24 h after inoculationBALB/c1-day-oldi.c.EV71/pSVA-MP4 #B3[104]
VP1-specific mAbi.p. injection at 3, 24, and 48 h after inoculationSCARB2-Tg1-day & 7-day-olds.c.E59 & 5746-TW98 *B4 & C2[105]
human plasma or IVIGin vitro pre-mix with EV71 at 37 °C for 1 hICR2-day-oldi.p.KM593929 *C4[106]
human IVIG3 i.p. injections at 4 h, 1- and 2-days after inoculationKunming mice7-day-oldi.p.AH08/06 *C4[107]
EV71-specific Abi.p. injection 1 day before and 1 day after (ICR), or 2 and 4 days after inoculation (C57BL/6)ICR & C57BL/67-day & 9-day-oldoralM2 #C2[44]
adult immune serai.p. injection at 1hr before and 24 h after inoculationyoung gerbils21-day-oldi.p. or i.m.strain 58301 *C4[108]
human IVIGi.v. infusion at a dosage of 1 g/kg/day for 2 dayshuman patients<2-yr-oldnatural infectionN/AN/A[17]
Immune modulators
Poly (I:C)i.p. injection at 12 h before inoculationICR3-day-oldi.p. or oralMP4 #C2[45]
Ad-IFN-aone intranasal shot within 12 h post-inoculationBALB/c6-day-oldi.p.strain 41 *B4[71]
antagomir -146ai.p. injection before or after virus inoculationC57BL/67-day-oldi.p.mEV71 #B2[109]
GS-9620oral uptake at 2, 26, 50 h post-inoculationICR10-day-oldi.p.MP10 #C4[95]
anti-IL6 Abi.p. co-injection of Ab and virus (day 0)BALB/c1-day-oldi.p.strain 41 *B4[38]
complement inhibitor (CR2-crry)treatment post-inoculationICR7-day-oldi.c.BrCr *A[97]
Retro-2cycli.p. injection following EV71 inoculationBALB/c<1-day-oldi.c.KJ508817 *C4[98]
Pleconarildaily i.p. injection for 5 daysICR1-day-oldi.p.BrCr *A[99]
andrographolide sulfonatei.p. injection once daily until 10 days post-inoculationICR7-day-oldi.p.BJ09/07 #C4[100]
adoptive transfer of macrophagei.p. injection with adult macrophage at 1 day post-inoculationICR10-day-oldi.p.MP10 #C4[101]
Milrinonei.v. injection within 2–6 h after admission at dosage 0.35–0.55 mg/kg/min for 72 h.human patients<2-yr-oldnatural infectionN/AN/A[22]
i.p.: intraperitoneal; i.v.: intravenous; i.c.: intracranial; i.m.: intra-muscular; s.c.: subcutaneous; N/A: information not available in the original paper; * clinical isolates; # mouse-adapted strain.

Share and Cite

MDPI and ACS Style

Shih, C.; Liao, C.-C.; Chang, Y.-S.; Wu, S.-Y.; Chang, C.-S.; Liou, A.-T. Immunocompetent and Immunodeficient Mouse Models for Enterovirus 71 Pathogenesis and Therapy. Viruses 2018, 10, 674.

AMA Style

Shih C, Liao C-C, Chang Y-S, Wu S-Y, Chang C-S, Liou A-T. Immunocompetent and Immunodeficient Mouse Models for Enterovirus 71 Pathogenesis and Therapy. Viruses. 2018; 10(12):674.

Chicago/Turabian Style

Shih, Chiaho, Chun-Che Liao, Ya-Shu Chang, Szu-Yao Wu, Chih-Shin Chang, and An-Ting Liou. 2018. "Immunocompetent and Immunodeficient Mouse Models for Enterovirus 71 Pathogenesis and Therapy" Viruses 10, no. 12: 674.

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop