Search Results (26)

Arthropod-borne viruses (arboviruses) are an increasingly significant threat to public health in tropical regions. In this study, we investigated the seroprevalence of various arboviruses in two species of sloth (Choloepus hoffmanni and Bradypus variegatus) in rural and peri-urban areas of Western Panama province. Between 2013 and 2018, blood samples from 60 sloths were tested for neutralizing antibodies against ten arboviruses. Significant variation in seroprevalence of different arboviruses was observed: 6.7% of sloths were seropositive for Madariaga virus, 6.7% for Venezuelan equine encephalitis virus, and 4.8% for Oropouche virus, while none were seropositive for dengue type 2, Zika, chikungunya, Una, Mayaro, or Punta Toro viruses. Notably, two Changuinola virus (CGLV) strains, which were previously isolated from Panamanian sloths in the 1970s, showed high seroprevalence: Pansloth 149 (23.3%) and D50 (53.3%). Given the high seroprevalence detected in our study and the lack of genomic characterization of the historical Pansloth 149 isolate, we performed next-generation sequencing of its complete genome using Illumina technology to understand its genetic diversity and evolutionary relationship with other CGLV strains. Full article

A novel ephemeral fever rhabdovirus and a CHeRI orbivirus of a previously unidentified genetic lineage were isolated in mosquito cell line C6/36 cells as co-infecting agents from the spleen tissue of a dead farmed white-tailed deer (WTD; Odocoileus virginianus) in Florida. We designated the ephemeral fever rhabdovirus as Hardee County ephemerovirus 1, strain CHeRI ephemerovirus 1. The genetic sequences of the CHeRI orbivirus isolated in this work differ significantly from those of three previously described CHeRI orbivirus lineages. We designated this new virus as CHeRI orbivirus 4, strain CHeRI orbivirus 4-1. Whereas it remains unknown whether one, both, or none of the viruses contributed to the pathology, gross observations revealed that the dead WTD had severely congested and hemorrhagic lungs, and that its heart, kidneys, and spleen were also congested. Full article

Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are vector-borne orbiviruses that pose an emerging threat to livestock, including cattle and sheep. This review summarizes the global distribution, genetic diversity, and key factors driving their spread along with the existing knowledge gaps and recommendations to mitigate their impact. Both viruses cause hemorrhagic disease in susceptible ruminants and are commonly reported in tropical and subtropical regions including North America, Asia, Africa, Oceania, and some parts of Europe. The geographical distribution of these viruses, encompassing 27 BTV and 7 EHDV serotypes, has shifted, particularly with the recent invasion of BTV-3, 4, and 8 and EHDV-8 serotypes in Europe. Several factors contribute to the recent spread of these viruses such as the distribution of virulent strains by the movement of temperature-dependent Culicoides vectors into new areas due to rapid climate change, the reassortment of viral strains during mixed infections, and unrestricted global trade. These diseases cause significant economic impacts including morbidity, mortality, reduced production, high management costs, and the disruption of international trade. Effective prevention and control strategies are paramount and rely on vaccination, vector control using insecticides, and the destruction of breeding sites, husbandry practices including the isolation and quarantine of infected hosts, restriction of animal movement, prompt diagnosis and identification of circulating strains, and effective surveillance and monitoring plans such as the pre-export and post-import screening of semen used for artificial insemination. However, challenges remain with intercontinental virus spread, live vaccines, and the failure of inactivated vaccines to produce protective immunity against dissimilar strains. Significant knowledge gaps highlight the need for a better scientific understanding and a strategic plan to ensure healthy livestock and global food security. Full article

A newly formatted enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to bluetongue virus (BTV) was developed and validated for bovine and ovine sera and plasma. Validation of the new sandwich ELISA (sELISA) was achieved with 949 negative bovine and ovine sera from BTV endemic and non-endemic areas of Australia and 752 BTV positive (field and experimental) sera verified by VNT and/or PCR. The test diagnostic sensitivity (DSe) and diagnostic specificity (DSp) were 99.70% and 99.20%, respectively, for bovine sera, and 97.80% and 99.50%, respectively, for ovine sera. Comparable diagnostic performances were noted for the sELISA compared to four competition ELISAs. While the sensitivity of the sELISA remained unaffected by BTV-15 positive sera, the cELISAs were not as sensitive. BTV-15 is endemic to Australia, and early warning depends on sensitive diagnoses of all serotypes: endemic or incurring. The sELISA failed to discriminate against epizootic hemorrhagic disease virus (EHDV) antibodies, the most serologically related orbivirus to BTV. The ACDP cELISA and the IDEXX kit showed cross-reactivity with some EHDV serotypes, with the least cross-reactive being the VMRD and the IDVet kits. Cross-reactivities, however, were also detected in sera raised experimentally from 10 isolates of the 21 known non-BTV orbiviruses. In this case, the sELISA was the least affected, followed equally by the VMRD and IDVet kits, and the IDEXX kit and the ACDP cELISA were the least discriminatory. In addition to exclusivity assessment of the ELISAs, an inclusivity assessment was made for all ELISAs using well characterized reference sera positive for antibodies to all serotypes BTV-1 to BTV-24. Full article

The past three decades have seen an increasing number of emerging arthropod-borne viruses in temperate regions This process is ongoing, driven by human activities such as inter-continental travel, combined with the parallel emergence of invasive arthropods and an underlying change in climate that can increase the risk of virus transmission and persistence. In addition, natural events such as bird migration can introduce viruses to new regions. Despite the apparent regularity of virus emergence, arthropod-borne viruses circulating in temperate regions face the challenge of the late autumn and winter months where the arthropod vector is inactive. Viruses therefore need mechanisms to overwinter or they will fail to establish in temperate zones. Prolonged survival of arthropod-borne viruses within the environment, outside of both vertebrate host and arthropod vector, is not thought to occur and therefore is unlikely to contribute to overwintering in temperate zones. One potential mechanism is continued infection of a vertebrate host. However, infection is generally acute, with the host either dying or producing an effective immune response that rapidly clears the virus. There are few exceptions to this, although prolonged infection associated with orbiviruses such as bluetongue virus occurs in certain mammals, and viraemic vertebrate hosts therefore can, in certain circumstances, provide a route for long-term viral persistence in the absence of active vectors. Alternatively, a virus can persist in the arthropod vector as a mechanism for overwintering. However, this is entirely dependent on the ecology of the vector itself and can be influenced by changes in the climate during the winter months. This review considers the mechanisms for virus overwintering in several key arthropod vectors in temperate areas. We also consider how this will be influenced in a warming climate. Full article

African horse sickness is a devastating viral disease of equids. It is transmitted by biting midges of the genus Culicoides with mortalities reaching over 90% in naïve horses. It is endemic to sub-Saharan Africa and is seasonally endemic in many parts of southern Africa. However, outbreaks in Europe and Asia have occurred that caused significant economic issues. There are attenuated vaccines available for control of the virus but concerns regarding the safety and efficacy means that alternatives are sought. One promising alternative is the use of virus-like particles in vaccine preparations, which have the potential to be safer and more efficacious as vaccines against African horse sickness. These particles are best made in a complex, eukaryotic system, but due to technical challenges, this may cause significant economic strain on the developing countries most affected by the disease. Therefore, this review also summarises the success so far, and potential, of recombinant protein expression in plants to reduce the economic strain of production. Full article

(1) Background: Epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV) are orbiviruses that cause hemorrhagic disease (HD) with significant economic and population health impacts on domestic livestock and wildlife. In the United States, white-tailed deer (Odocoileus virginianus) are particularly susceptible to these viruses and are a frequent blood meal host for various species of Culicoides biting midges (Diptera: Ceratopogonidae) that transmit orbiviruses. The species of Culicoides that transmit EHDV and BTV vary between regions, and larval habitats can differ widely between vector species. Understanding how midges are distributed across landscapes can inform HD virus transmission risk on a local scale, allowing for improved animal management plans to avoid suspected high-risk areas or target these areas for insecticide control. (2) Methods: We used occupancy modeling to estimate the abundance of gravid (egg-laden) and parous (most likely to transmit the virus) females of two putative vector species, C. stellifer and C. venustus, and one species, C. haematopotus, that was not considered a putative vector. We developed a universal model to determine habitat preferences, then mapped a predicted weekly midge abundance during the HD transmission seasons in 2015 (July–October) and 2016 (May–October) in Florida. (3) Results: We found differences in habitat preferences and spatial distribution between the parous and gravid states for C. haematopotus and C. stellifer. Gravid midges preferred areas close to water on the border of well and poorly drained soil. They also preferred mixed bottomland hardwood habitats, whereas parous midges appeared less selective of habitat. (4) Conclusions: If C. stellifer is confirmed as an EHDV vector in this region, the distinct spatial and abundance patterns between species and physiological states suggest that the HD risk is non-random across the study area. Full article

Kemerovo virus (KEMV) is a tick-borne orbivirus transmitted by ticks of the genus Ixodes. Previous animal experimentation studies with orbiviruses, in particular the interferon receptor double knock-out (IFNAR^(−/−)) mouse model, did not indicate bias that is related to age or sex. We endeavoured to assess the effect of serial and alternated passages of KEMV in mammalian or Ixodes cells on virus replication and potential virulence in male or female IFNAR^(−/−) mice, with important age differences: younger males (4–5 months old), older males (14–15 months old), and old females (14–15 months old). After 30 serial passages in mammalian or tick cells, or alternated passages in the two cell types, older female mice which were inoculated with the resulting virus strains were the first to show clinical signs and die. Younger males behaved differently from older males whether they were inoculated with the parental strain of KEMV or with any of the cell culture-passaged strains. The groups of male and female mice inoculated with the mammalian cell culture-adapted KEMV showed the lowest viraemia. While older female and younger male mice died by day 6 post-inoculation, surprisingly, the older males survived until the end of the experiment, which lasted 10 days. RNA extracted from blood and organs of the various mice was tested by probe-based KEMV real-time RT-PCR. Ct values of the RNA extracts were comparable between older females and younger males, while the values for older males were >5 Ct units higher for the various organs, indicating lower levels of replication. It is noteworthy that the hearts of the old males were the only organs that were negative for KEMV RNA. These results suggest, for the first time, an intriguing age- and sex-related bias for an orbivirus in this animal model. Changes in the amino acid sequence of the RNA-dependent RNA polymerase of Kemerovo virus, derived from the first serial passage in Ixodes cells (KEMV Ps.IRE1), were identified in the vicinity of the active polymerase site. This finding suggests that selection of a subpopulation of KEMV with better replication fitness in tick cells occurred. Full article

Bluetongue Virus (BTV) and Epizootic Hemorrhagic Disease Virus (EHDV) are Orbiviruses primarily transmitted by their biological vector, Culicoides spp. Latreille, 1809 (Diptera: Ceratopogonidae). These viruses can infect a diverse range of vertebrate hosts, leading to disease outbreaks in domestic and wild ruminants worldwide. This study, conducted at the Belo Horizonte Municipal Parks and Zoobotany Foundation (FPMZB-BH), Minas Gerais, Brazil, focused on Orbivirus and its vectors. Collections of Culicoides spp. were carried out at the FPMZB-BH from 9 December 2021 to 18 November 2022. A higher prevalence of these insects was observed during the summer months, especially in February. Factors such as elevated temperatures, high humidity, fecal accumulation, and proximity to large animals, like camels and elephants, were associated with increased Culicoides capture. Among the identified Culicoides spp. species, Culicoides insignis Lutz, 1913, constituted 75%, and Culicoides pusillus Lutz, 1913, 6% of the collected midges, both described as competent vectors for Orbivirus transmission. Additionally, a previously unreported species in Minas Gerais, Culicoides debilipalpis Lutz, 1913, was identified, also suspected of being a transmitter of these Orbiviruses. The feeding preferences of some Culicoides species were analyzed, revealing that C. insignis feeds on deer, Red deer (Cervus elaphus) and European fallow deer (Dama dama). Different Culicoides spp. were also identified feeding on humans, raising concerns about the potential transmission of arboviruses at the site. In parallel, 72 serum samples from 14 susceptible species, including various Cervids, collected between 2012 and 2022 from the FPMZB-BH serum bank, underwent Agar Gel Immunodiffusion (AGID) testing for BTV and EHDV. The results showed 75% seropositivity for BTV and 19% for EHDV. Post-testing analysis revealed variations in antibody presence against BTV in a tapir and a fallow deer and against EHDV in a gemsbok across different years. These studies confirm the presence of BTV and EHDV vectors, along with potential virus circulation in the zoo. Consequently, implementing control measures is essential to prevent susceptible species from becoming infected and developing clinical diseases. Full article

Non-structural protein 4 (NS4) of insect-borne and tick-borne orbiviruses is encoded by genome segment 9, from a secondary open reading frame. Though a protein dispensable for bluetongue virus (BTV) replication, it has been shown to counter the interferon response in cells infected with BTV or African horse sickness virus. We further explored the functional role(s) of NS4 proteins of BTV and the tick-borne Great Island virus (GIV). We show that NS4 of BTV or GIV helps an E3L deletion mutant of vaccinia virus to replicate efficiently in interferon-treated cells, further confirming the role of NS4 as an interferon antagonist. Our results indicate that ectopically expressed NS4 of BTV localised with caspase 3 within the nucleus and was found in a protein complex with active caspase 3 in a pull-down assay. Previous studies have shown that pro-apoptotic caspases (including caspase 3) suppress type I interferon response by cleaving mediators involved in interferon signalling. Our data suggest that orbivirus NS4 plays a role in modulating the apoptotic process and/or regulating the interferon response in mammalian cells, thus acting as a virulence factor in pathogenesis. Full article

Bioinformatic analyses have predicted that orbiviruses encode an additional, small non-structural protein (NS5) from a secondary open reading frame on genome segment 10. However, this protein has not previously been detected in infected mammalian or insect cells. NS5-specific antibodies were generated in mice and were used to identify NS5 synthesised in orbivirus-infected BSR cells or cells transfected with NS5 expression plasmids. Confocal microscopy shows that although NS5 accumulates in the nucleus, particularly in the nucleolus, which becomes disrupted, it also appears in the cell cytoplasm, co-localising with mitochondria. NS5 helps to prevent the degradation of ribosomal RNAs during infection and reduces host-cell protein synthesis However, it helps to extend cell viability by supporting viral protein synthesis and virus replication. Pulldown studies showed that NS5 binds to ssRNAs and supercoiled DNAs and demonstrates interactions with ZBP1, suggesting that it modulates host-cell responses. Full article

African horse sickness is a deadly and highly infectious disease of equids, caused by African horse sickness virus (AHSV). AHSV is one of the most economically important members of the Orbivirus genus. AHSV is transmitted by the biting midge, Culicoides, and therefore replicates in both insect and mammalian cell types. Structural protein VP7 is a highly conserved major core protein of orbiviruses. Unlike any other orbivirus VP7, AHSV VP7 is highly insoluble and forms flat hexagonal crystalline particles of unknown function in AHSV-infected cells and when expressed in mammalian or insect cells. To examine the role of AHSV VP7 in virus replication, a plasmid-based reverse genetics system was used to generate a recombinant AHSV that does not form crystalline particles. We characterised the role of VP7 crystalline particle formation in AHSV replication in vitro and found that soluble VP7 interacted with viral proteins VP2 and NS2 similarly to wild-type VP7 during infection. Interestingly, soluble VP7 was found to form uncharacteristic tubule-like structures in infected cells which were confirmed to be as a result of unique VP7-NS1 colocalisation. Furthermore, it was found that VP7 crystalline particles play a role in AHSV release and yield. This work provides insight into the role of VP7 aggregation in AHSV cellular pathogenesis and contributes toward the understanding of the possible effects of viral protein aggregation in other human virus-borne diseases. Full article

Bluetongue virus (BTV) and African horse sickness virus (AHSV) are widespread arboviruses that cause important economic losses in the livestock and equine industries, respectively. In addition to these, another arthropod-transmitted orbivirus known as epizootic hemorrhagic disease virus (EHDV) entails a major threat as there is a conducive landscape that nurtures its emergence in non-endemic countries. To date, only vaccinations with live attenuated or inactivated vaccines permit the control of these three viral diseases, although important drawbacks, e.g., low safety profile and effectiveness, and lack of DIVA (differentiation of infected from vaccinated animals) properties, constrain their usage as prophylactic measures. Moreover, a substantial number of serotypes of BTV, AHSV and EHDV have been described, with poor induction of cross-protective immune responses among serotypes. In the context of next-generation vaccine development, antigen delivery systems based on nano- or microparticles have gathered significant attention during the last few decades. A diversity of technologies, such as virus-like particles or self-assembled protein complexes, have been implemented for vaccine design against these viruses. In this work, we offer a comprehensive review of the nano- and microparticulated vaccine candidates against these three relevant orbiviruses. Additionally, we also review an innovative technology for antigen delivery based on the avian reovirus nonstructural protein muNS and we explore the prospective functionality of the nonstructural protein NS1 nanotubules as a BTV-based delivery platform. Full article

From 1975 to 2021, the United Arab Emirates (UAE) imported more than 1300 live Arabian oryxes (AOs) and scimitar-horned oryxes (SHOs) for conservation programs. The objective of this study was to estimate the prevalence of orbiviruses Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) in AOs and SHOs from captive herds in the UAE. Between October 2014 and April 2015, 16 AOs and 13 SHOs originating from Texas (USA) and 195 out of about 4000 SHOs from two locations in the UAE were blood sampled to be tested by indirect enzyme-linked immunosorbent assay (ELISA) and real-time reverse transcriptase polymerase chain reaction (RT-qPCR) assays. Eight imported AOs (50% CI [24.7–75.4%]) and eight imported SHOs (61.5% CI [31.6–86.1%]) were found BTV seropositive, in contrast with three out of 195 SHOs (1.5% CI [0.3–4.4%]) from the Emirates. BTV-2 genome was detected in 6/16 of the Arabian Oryx, and amongst those, one out of six was seronegative. None of the tested samples was found positive for EHDV. Our results illustrate the wide local variation regarding BTV seroprevalence in domestic and wild ruminants in the Arabian Peninsula. These results stress the need for pre-import risk assessment when considering translocation of wild ruminant species susceptible to orbiviruses not only in the country of destination but also where transit happens. Full article

Statin derivatives can inhibit the replication of a range of viruses, including hepatitis C virus (HCV, Hepacivirus), dengue virus (Flavivirus), African swine fever virus (Asfarviridae) and poliovirus (Picornaviridae). We assess the antiviral effect of fluvastatin in cells infected with orbiviruses (bluetongue virus (BTV) and Great Island virus (GIV)). The synthesis of orbivirus outer-capsid protein VP2 (detected by confocal immunofluorescence imaging) was used to assess levels of virus replication, showing a reduction in fluvastatin-treated cells. A reduction in virus titres of ~1.7 log (98%) in fluvastatin-treated cells was detected by a plaque assay. We have previously identified a fourth non-structural protein (NS4) of BTV and GIV, showing that it interacts with lipid droplets in infected cells. Fluvastatin, which inhibits 3-hydroxy 3-methyl glutaryl CoA reductase in the mevalonic acid pathway, disrupts these NS4 interactions. These findings highlight the role of the lipid pathways in orbivirus replication and suggest a greater role for the membrane-enveloped orbivirus particles than previously recognised. Chemical intermediates of the mevalonic acid pathway were used to assess their potential to rescue orbivirus replication. Pre-treatment of IFNAR^(−/−) mice with fluvastatin promoted their survival upon challenge with live BTV, although only limited protection was observed. Full article