Search Results (368)

Background/Objectives: Swine influenza A virus (swIAV), a prevalent respiratory pathogen in porcine populations, poses substantial economic losses to global livestock industries and represents a potential threat to public health security. Neuraminidase (NA) has been proposed as an important component for universal influenza vaccine development. NA has potential advantages as a vaccine antigen in providing cross-protection, with specific antibodies that have a broad binding capacity for heterologous viruses. In this study, we evaluated the immunogenicity and protective efficacy of a tetrameric recombinant NA subunit vaccine in a swine model. Methods: We constructed and expressed structurally stable soluble tetrameric recombinant NA (rNA) and prepared subunit vaccines by mixing with ISA 201 VG adjuvant. The protective efficacy of rNA-ISA 201 VG was compared to that of a commercial whole inactivated virus vaccine. Pigs received a prime-boost immunization (14-day interval) followed by homologous viral challenge 14 days post-boost. Results: Both rNA-ISA 201 VG and commercial vaccine stimulated robust humoral responses. Notably, the commercial vaccine group exhibited high viral-binding antibody titers but very weak NA-specific antibodies, whereas rNA-ISA 201 VG immunization elicited high NA-specific antibody titers alongside substantial viral-binding antibodies. Post-challenge, both immunization with rNA-ISA 201 VG and the commercial vaccine were effective in inhibiting viral replication, reducing viral load in porcine respiratory tissues, and effectively mitigating virus-induced histopathological damage, as compared to the PBS negative control. Conclusions: These findings found that the anti-NA immune response generated by rNA-ISA 201 VG vaccination provided protection comparable to that of a commercial inactivated vaccine that primarily induces an anti-HA response. Given that the data are derived from one pig per group, there is a requisite to increase the sample size for more in-depth validation. This work establishes a novel strategy for developing next-generation SIV subunit vaccines leveraging NA as a key immunogen. Full article

Background: Canine parvovirus (CPV) is a highly pathogenic virus that predominantly affects puppies, with mortality rates exceeding 70%. Although commercial multivalent live attenuated vaccines (MLV) are widely employed, their efficacy is often compromised by maternal antibody interference. Consequently, the development of novel vaccines remains imperative for effective CPV control. Methods: Recombinant CPV VP2 protein (rVP2) and canine interlukine 12 protein (rcIL-12) were expressed using the Bac-to-Bac baculovirus expression system and the biological activity of these proteins was assessed through hemagglutination, Cell Counting Kit-8 (CCK8) and IFN-γ induction assays. The combined immunoenhancement effect of rVP2 and rcIL-12 protein was evaluated in puppies. Results: Both rVP2 and rcIL-12 were successfully expressed and purified, exhibiting confirmed antigenicity, immunogenicity, and bioactivity. Co-administration of rVP2 with rcIL-12 elicited higher neutralizing antibody titer (6–7 times higher), complete challenge protection efficiency (no clinical symptoms and tissue and organ lesions), fewer viral shedding (decreasing significantly 8-day post challenge) and superior viral blockade (lower viral load in the organism) compared to rVP2 alone. Conclusions: Our findings demonstrate that rVP2 co-administered with rcIL-12 induces robust protective immunity in puppies and significantly mitigated the inhibitory effects of maternal antibodies. This represents a promising strategy for enabling earlier vaccination in puppies and rational design of CPV subunit vaccines. Full article

Background/Objectives: More than 33 billion chickens are industrially raised for meat and egg production globally and vaccinated against Marek’s disease virus (MDV). The antigenically related herpesvirus of turkey (HVT) is used as a live-attenuated vaccine, commonly provided as a recombinant vector to protect chickens against additional unrelated pathogens. Because HVT replicates in a strictly cell-associated fashion to low levels of infectious units, adherent primary chicken or duck embryo fibroblasts are infected, dislodged from the cultivation surface and distributed as cryocultures in liquid nitrogen to the site of application. Although viable cells are complex products, application of infected cells in ovo confers protection even in presence of maternal antibodies. Methods/Results: The aim of our study was to determine whether a continuous cell line in a scalable cultivation format can be used for production of HVT-based vaccines. The AGE1.CR cell line (from Muscovy duck) was found to be highly permissive in adherent cultures. Propagation in suspension, however, initially gave very low yields. The induction of cell-to-cell contacts in carrier-independent suspensions and a metabolic shock improved titers to levels suitable for vaccine production (>10⁵ infectious units/mL after infection with multiplicity of 0.001). Conclusions: Production of HVT is challenging to scale to large volumes and the reliance on embryonated eggs from biosecure facilities is complex. We demonstrate that a cell-associated HVT vector can be propagated in a carrier-independent suspension culture of AGE1.CR cells in chemically defined medium. The fed-batch production is independent of primary cells and animal-derived material and can be scaled to large volumes. Full article

Background and Objectives: To evaluate the mRNA vaccine platform for blood-stage Plasmodium parasites, we completed a proof-of-concept study using the P. yoelii mouse model of malaria and two mRNA-based vaccines. Both encoded PyMSP1₁₉ fused to PyMSP8 (PyMSP1/8). One was designed for secretion of the encoded protein (PyMSP1/8-sec); the other encoded membrane-bound antigen (PyMSP1/8-mem). Methods: Secretion of PyMSP1/8-sec and membrane localization of PyMSP1/8-mem were verified in mRNA-transfected cells. As recombinant PyMSP1/8 (rPyMSP1/8) is known to protect mice against lethal P. yoelii 17XL infection, we first compared immunogenicity and efficacy of the PyMSP1/8-sec mRNA vaccine versus the recombinant formulation in outbred mice. Animals were immunized three times followed by challenge with a lethal dose of P. yoelii 17XL-parasitized RBCs (pRBCs). Similar immunization and challenge experiments were conducted to compare PyMSP1/8-sec versus PyMSP1/8-mem mRNA vaccines. Results: Immunogenicity of the PyMSP1/8-sec mRNA vaccine was superior to the recombinant formulation, inducing higher antibody titers against both vaccine components. Following challenge with P. yoelii 17XL pRBCs, all PyMSP1/8-sec-immunized animals survived, with 50% of these showing no detectible pRBCs in circulation (<0.01%). In addition, mean peak parasitemia in PyMSP1/8-sec mRNA-immunized mice was significantly lower than that in the rPyMSP1/8 vaccine group. Both PyMSP1/8-sec and PyMSP1/8-mem were protective against P. yoelii 17XL challenge, with PyMSP1/8-mem immunization providing a significantly higher level of protection than PyMSP1/8-sec immunization considering the number of animals with no detectable pRBCs in circulation and the mean peak parasitemia in animals with detectable parasitemia. Conclusions: mRNA vaccines were highly immunogenic and potently protective against blood-stage malaria, outperforming a similar recombinant-based vaccine. The membrane-bound antigen was more effective at inducing protective antibody responses, highlighting the need to consider antigen localization for mRNA vaccine design. Full article

Background: Rabbit hemorrhagic disease (RHD) is an acute, hemorrhagic and highly lethal infectious disease caused by rabbit hemorrhagic disease virus (RHDV), which causes huge economic losses to the rabbit breeding industry. Moreover, there is limited cross-protection between the two different serotypes of classic RHDV (GI.1) and RHDV2 (GI.2). The shortcomings of traditional inactivated vaccines have led to the development of novel subunit vaccines that can protect against both strains, and the VP60 capsid protein is the ideal antigenic protein. This study focused on developing a bivalent RHDV vaccine that can prevent infection with both GI.1 and GI.2 strains. Methodology: Baculovirus vectors containing classic RHDV and RHDV2 VP60 were co-transfected with linearized baculovirus into sf9 cells and transferred to baculovirus via homologous recombination of the VP60 gene. Infected sf9 cells were lysed, and after purification via Ni-NTA chromatography, VLPs were observed using transmission electron microscopy (TEM). In order to evaluate the immunogenicity of the chimeric RHDV VLP vaccine in rabbits, the RHDV VP60-specific antibody, IL-4, IFN-γ and neutralizing antibody titers were analyzed in serum using ELISA and HI. Results: The recombinant baculovirus system successfully expressed chimeric RHDV VLPs with a diameter of 32–40 nm. After immunization, it could produce specific antibodies, IL-4 and IFN-γ. Following the second immunization, neutralizing antibodies, determined using hemagglutination inhibition (HI) assays, were elicited. Conclusions: These data show that the chimeric RHDV VLP bivalent vaccine for immunized New Zealand rabbits can induce humoral immunity and cellular immunity in vivo, and the immunization effect of the high-dose group is similar to that of the current commercial vaccine. Full article

Brucellosis, caused by Brucella species, remains a significant zoonotic disease affecting both human and animal health worldwide. Among the outer membrane proteins (Omps) of Brucella, Omp16 has emerged as a key immunogenic target with potential applications in vaccine development and diagnostics. Omp16, a lipidated peptidoglycan-associated lipoprotein, stimulates a strong proinflammatory response and is essential for maintaining the bacterial outer membrane integrity and facilitating host cell invasion. This review examines the immunogenic properties of Omp16, its role in Brucella pathogenesis, and its potential as a candidate for vaccine development. We discuss how Omp16-based vaccines, including recombinant proteins, outer membrane vesicles, and viral vector vaccines, have shown promise in providing protection against Brucella infections in animal models. Additionally, Omp16’s utility in diagnostic applications, particularly in enzyme-linked immunosorbent assays (ELISA), offers a reliable method for detecting brucellosis in both humans and animals. Overall, Omp16 represents a crucial antigen with significant potential for advancing both the diagnosis and prevention of brucellosis, offering insights into the next generation of brucellosis vaccines and diagnostic tools. Full article

Coccidiosis, caused by Eimeria spp., significantly reduces poultry productivity and causes major economic losses. Traditional control methods are limited by drug resistance and high production costs. Recent genomic and bioinformatic advances have enabled the identification of novel antigens, making recombinant subunit vaccines a promising next-generation strategy by eliciting robust cellular and humoral immune responses. This study investigates the E. necatrix gametocyte protein 56 (EnGAM56) as a potential candidate for recombinant subunit vaccines. The full-length E. necatrix gametocyte gam56 gene (Engam56-F) was amplified, expressed in vitro, and characterized via SDS-PAGE and Western blot. Immunofluorescence assays revealed that EnGAM56-F is specifically localized in gametocytes and unsporulated oocysts. Chickens immunized with recombinant proteins (rEnGAM56-F and rEnGAM56-T) were evaluated for immunoprotection against E. necatrix infection through lesion scores, weight gain, oocyst production, anticoccidial index (ACI), and antibody and cytokine levels. The synergistic effects were evaluated by employing various combinations of recombinant proteins, including rEtGAM22, rEtGAM56-T, and rEtGAM59. Results showed that EnGAM56-F encodes a 468-amino acid protein with distinct tyrosine-serine-rich and proline-methionine-rich regions. rEnGAM56-F was specifically recognized by both anti-6 × His tag antibodies and convalescent serum from chickens infected with E. necatrix. Both rEnGAM56-F and rEnGAM56-T provided immune protection, with rEnGAM56-T showing superior efficacy. The combination of rEnGAM (22 + 59 + 56-T) yielded the strongest immune response, followed by rEnGAM (22 + 56-T). These findings highlight the potential of EnGAM56 as a candidate for recombinant subunit anticoccidial vaccines. Full article

Background/Objectives: The emergence of multidrug-resistant Acinetobacter baumannii (MDR A. baumannii) as a leading cause of fatal hospital-acquired infections underscores the urgent need for effective vaccines. While oral vaccines using live Bacillus subtilis spores expressing A. baumannii TonB-dependent receptor (TBDR) show promise, biosafety concerns regarding recombinant spore persistence necessitate alternative strategies. Here, we evaluated chemically inactivated B. subtilis spores displaying TBDR as a safer yet immunogenic vaccine candidate. Methods: Recombinant spores were inactivated using iron-ethanol sporicidal solution and administered to BALB/c mice (8–12 weeks old) to assess safety and immunogenicity. Toxicity was evaluated through clinical monitoring, serum biochemistry, and histopathology. Immune responses were characterized by T/B cell activation, IgG/IgA titers, and mucosal sIgA levels. Protective efficacy was determined by challenging immunized mice with MDR A. baumannii Ab35 and quantifying bacterial loads and examining tissue pathology. Results: The inactivated spores exhibited an excellent safety profile, with no adverse effects on clinical parameters, organ function, or tissue integrity. Immunization induced robust systemic and mucosal immunity, evidenced by elevated CD4+/CD8+ T cells, B cells, and antigen-specific IgG/IgA in serum and mucosal secretions. Following the challenge, vaccinated mice showed significantly reduced pulmonary bacterial burdens (>90% reduction), and preserved lung and spleen architecture compared to controls, which developed severe inflammation and tissue damage. Conclusions: These findings demonstrate that inactivated B. subtilis spores expressing TBDR are a safe, orally administrable vaccine platform that elicits protective immunity against MDR A. baumannii. By addressing biosafety concerns associated with live spores while maintaining efficacy, this approach represents a critical advance toward preventing high-risk nosocomial infections. Full article

Foot-and-mouth disease virus (FMDV) continues to pose a significant threat to livestock health and the global agricultural economy, particularly in endemic regions of Asia, Africa, and the Middle East. Current vaccines based on chemically inactivated FMDV present several challenges, including biosafety risks, high production costs, and limited effectiveness against emerging viral variants. To overcome these limitations, we developed virus-like particle (VLP) vaccines targeting FMDV serotypes O, A, and Asia1 using a recombinant Escherichia coli expression system. The resulting VLPs self-assembled into 25–30 nm particles with native-like morphology and antigenic properties, as confirmed by transmission electron microscopy, SDS-PAGE, and Western blot analysis. Immunogenicity was evaluated in mice and pigs using ELISA and virus neutralization tests (VNT), and protective efficacy was assessed through viral challenge studies. All VLPs induced strong serotype-specific antibody responses, with ELISA PI values exceeding 50% and significantly increased VNT titers after booster immunization. In mice, PD₅₀ values were 73.5 (A-type), 32.0 (O-type), and 55.7 (Asia1-type); in pigs, PD₅₀ values reached 10.6 (O-type) and 22.6 (Asia1-type). Notably, the vaccines induced robust immune responses even at lower antigen doses, suggesting the feasibility of dose-sparing formulations. These findings demonstrate that FMDV VLPs produced in E. coli are highly immunogenic and capable of eliciting protective immunity, highlighting their promise as safe, scalable, and cost-effective alternatives to conventional inactivated FMD vaccines. Full article

Cases of new COVID-19 infection, which manifested in 2019 and caused a global socioeconomic crisis, still continue to be registered worldwide. The high mutational activity of SARS-CoV-2 leads to the emergence of new antigenic variants of the virus, which significantly reduces the effectiveness of COVID-19 vaccines, as well as the sensitivity of diagnostic test systems based on variable viral antigens. These problems may be solved by focusing on highly conserved coronavirus antigens, for example nucleocapsid (N) protein, which is actively expressed by coronavirus-infected cells and serves as a target for the production of virus-specific antibodies and T cell responses. It is known that anti-N antibodies are non-neutralizing, but their protective potential and functional activity are not sufficiently studied. Here, the protective effect of anti-N antibodies was studied in Syrian hamsters passively immunized with polyclonal sera raised to N(B.1) recombinant protein. The animals were infected with 10⁵ or 10⁴ TCID₅₀ of SARS-CoV-2 (B.1, Wuhan or BA.2.86.1.1.18, Omicron) 6 h after serum passive transfer, and protection was assessed by weight loss, clinical manifestation of disease, viral titers in the respiratory tract, as well as by the histopathological evaluation of lung tissues. The functional activity of anti-N(B.1) antibodies was evaluated by complement-dependent cytotoxicity (CDC) and antibody-dependent cytotoxicity (ADCC) assays. The protection of anti-N antibodies was evident only against a lower dose of SARS-CoV-2 (B.1) challenge, whereas almost no protection was revealed against BA.2.86.1.1.18 variant. Anti-N(B.1) monoclonal antibodies were able to stimulate both CDC and ADCC. Thus, anti-N(B.1) antibodies possess protective activity against homologous challenge infection, which is possibly mediated by innate Fc-mediated immune reactions. These data may be informative for the development of N-based broadly protective COVID-19 vaccines. Full article

Background: Measles, an acute respiratory infectious disease caused by the measles virus, continues to pose a significant threat to children under five years old worldwide. Despite the availability of effective vaccines, challenges such as insufficient vaccination coverage and antigenic drift contribute to its persistence. Based on a newly isolated wild-type measles virus strain (genotype H1a), designated MVs/Jiangsu.CHN/38.16/1[H1a] (MV-1), this study aims to develop and evaluate a novel recombinant measles virus vaccine candidate designed to enhance immunogenicity and broaden protection against multiple epidemic genotypes. Methods: A recombinant measles virus vaccine candidate, designated rSchwarz/FH(H1a), was developed by incorporating immunogenic genes from the H1a genotype into the backbone of the Schwarz vaccine strain. The genetic stability, safety, and immunogenicity of this vaccine candidate were evaluated in preclinical models. Relevant sample sizes and methodologies were selected to ensure comprehensive assessment of vaccine efficacy against various genotypes (H1a, B3, D8). Results: The rSchwarz/FH(H1a) vaccine candidate demonstrated enhanced immunogenicity, with robust immune responses observed against the targeted genotypes. Additionally, it showed excellent genetic stability and safety profiles, indicating potential for effective use in vaccination programs. Notably, the vaccine provided cross-protection against multiple epidemic genotypes, highlighting its broader application in controlling measles outbreaks. Conclusions: Our findings suggest that the rSchwarz/FH(H1a) vaccine candidate represents a promising advancement in measles vaccine development. It has the potential to strengthen current measles vaccination strategies by providing improved immunogenicity and broader protection against different circulating genotypes. Further clinical trials are warranted to confirm these promising preclinical results. Full article

Background: Brucellosis poses a significant public health challenge, necessitating effective vaccine development. Current vaccines have limitations such as safety concerns and inadequate mucosal immunity. This study aims to develop an FcRn-targeted mucosal Brucella vaccine by fusing the human Fc domain with Brucella’s multi-epitope protein (MEV), proposing a novel approach for human brucellosis prevention. Methods: The study developed a recombinant antigen (h-tFc-MEV) through computational analyses to validate antigenicity, structural stability, solubility, and allergenic potential. Molecular simulations confirmed FcRn binding. The vaccine was delivered orally via chitosan nanoparticles in murine models. Immunization was compared to MEV-only immunization. Post-challenge assessments were conducted to evaluate protection against Brucella colonization. Mechanistic studies investigated dendritic cell activation and antigen presentation. Results: Computational analyses showed that the antigen had favorable properties without allergenic potential. Molecular simulations demonstrated robust FcRn binding. In murine models, oral delivery elicited enhanced systemic immunity with elevated serum IgG titers and amplified CD4+/CD8+ T-cell ratios compared to MEV-only immunization. Mucosal immunity was evidenced by significant IgA upregulation across multiple tracts. Long-term immune memory persisted for six months. Post-challenge assessments revealed markedly reduced Brucella colonization in visceral organs. Mechanistic studies identified FcRn-mediated dendritic cell activation through enhanced MHC-II expression and antigen presentation efficiency. Conclusions: The FcRn-targeted strategy establishes concurrent mucosal and systemic protective immunity against Brucella infection. This novel vaccine candidate shows potential for effective human brucellosis prevention, offering a promising approach to address the limitations of current vaccines. Full article

Background/Objectives: In the past, FhSAP-2, an 11.5 kDa recombinant protein belonging to the Fasciola hepatica saposin-like/NK-lysin family, has been shown to induce over 60% partial protection in immunized rabbits and mice when challenged with F. hepatica metacercariae. However, despite FhSAP-2 being a promising vaccine candidate, its hydrophobic nature has made its purification a challenging process. The present study aimed to determine whether a modified 9.8 kDa variant of protein (mFhSAP-2), lacking a string of 16 hydrophobic amino acids at the amino terminus and a dominant Th1 epitope, could retain its immunogenic and Th1-inducing properties. Methods: RAW264.7 cells were stimulated with mFhSAP-2, and TNFα levels were determined. C57BL/6 mice were immunized with mFhSAP-2 alone or emulsified with Montanide ISA50. Total anti-mFhSAP-2 IgG subtypes, along with their avidity and titers, were measured using ELISA. The T cell proliferation index and levels of CD4+/CD8+ and IFNγ/IL-4 ratios were determined. Results: In vitro, mFhSAP-2 induced dose-dependent TNFα production in RAW264.7 cells. In vivo, mice immunized with mFhSAP-2 or mFhSAP-2+ISA50 developed high-avidity IgG2a and IgG2c antibodies at levels that were significantly higher than IgG1 antibody levels. However, the mFhSAP-2+ISA50 formulation induced higher and more homogenous antibody titers than mFhSAP-2, suggesting that an adjuvant may be required to enhance mFhSAP-2 immunogenicity. Immunization with mFhSAP-2+ISA50 also induced significantly higher activated CD4+/CD8+ T cell ratios and IFNγ/IL-4 ratios compared to naïve mice. Conclusions: Our results demonstrate that mFhSAP-2 retained its immunogenicity and Th1-polarizing properties, which were enhanced by the Montanide ISA50 adjuvant. The present study highlights the feasibility of inducing Th1-associated immune responses in mice using mFhSAP-2 as an antigen. Further studies are required to assess the potential application of the mFhSAP-2+ISA50 formulation as a vaccine against F. hepatica in natural hosts such as cattle and sheep, which could contribute to improved control and aid in the prevention and eradication of F. hepatica infection. Full article

(1) Background: The currently circulating variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibits resistance to antibodies induced by vaccines. The World Health Organization recommended the use of monovalent XBB.1 sublineages (e.g., XBB.1.5) as an antigenic component in 2023. (2) Objective: In this study, we aimed to develop vaccines based on the XBB.1.5 receptor-binding domain (RBD) to combat the recently emerged SARS-CoV-2 XBB and JN.1 variants, as well as previously circulating variants. (3) Methods: Glycoengineered Pichia pastoris was utilized to produce a recombinant XBB.1.5 RBD protein with mammalian-like and fucose-free N-glycosylation. The XBB.1.5 RBD was mixed with Al(OH)₃:CpG adjuvants to prepare monovalent vaccines. Thereafter, the XBB.1.5 RBD was mixed with the Beta (B.1.351), Delta (B.1.617.2), or Omicron (BA.2) RBDs (1:1 ratio), along with Al(OH)₃:CpG, to prepare bivalent vaccines. BALB/c mice were immunized with the monovalent and bivalent vaccines. Neutralizing antibody titers were assessed via pseudovirus and authentic virus assays; humoral immune responses were analyzed by RBD-binding IgG subtypes. (4) Results: The monovalent vaccine induced higher neutralizing antibody titers against Delta, BA.2, XBB.1.5, and JN.1 compared to those in mice immunized solely with Al(OH)₃:CpG, as demonstrated by pseudovirus virus assays. The XBB.1.5/Delta RBD and XBB.1.5/Beta RBD-based bivalent vaccines provided potent protection against the BA.2, XBB.1.5, JN.1, and KP.2 variants, as well as the previously circulating Delta and Beta variants. All monovalent and bivalent vaccines induced high levels of RBD-binding IgG (IgG1, IgG2a, IgG2b, and IgG3) antibodies in mice, suggesting that they elicited robust humoral immune responses. The serum samples from mice immunized with the XBB.1.5 RBD-based and XBB.1.5/Delta RBD-based vaccines could neutralize the authentic XBB.1.16 virus. (5) Conclusions: The XBB.1.5/Beta and XBB.1.5/Delta RBD-based bivalent vaccines are considered as potential candidates for broad-spectrum vaccines against SARS-CoV-2 variants. Full article

Feline panleukopenia (FPL), caused by the feline panleukopenia virus (FPLV), is a severe and highly contagious viral disease with high morbidity and mortality. Vaccination remains the gold standard for preventing and controlling this debilitating condition. The viral protein VP2 serves as the major immunogen of FPLV and represents the key target antigen in the development of a novel FPLV vaccine. Virus-like particle (VLP)-based vaccines have emerged as next-generation vaccine candidates due to their high immunogenicity and safe profile. In this study, a baculovirus expression vector system (BEVS) was employed to generate FPLV-VLPs through recombinant expression of the VP2 protein of a Chinese epidemic strain (Ala91Ser, Ile101Thr) of FPLV. The resulting FPLV-VLPs demonstrated markedly enhanced antigenicity and hemagglutination activity, achieving a hemagglutination titer of up to 1:2¹⁶. Following vaccination, immunized cats developed high titers of anti-FPLV hemagglutination inhibition (HI) antibodies (1:2¹⁶) and exhibited 100% protection against challenge with a virulent epidemic FPLV variant (Ala91Ser, Ile101Thr). These findings demonstrate that FPLV-VLPs hold strong potential as candidates for a novel subunit vaccine against FPLV infection. Full article