Characterisation of two enteroviruses isolated from Australian brushtail possums (Trichosurus vulpecula) in New Zealand

Emergence of a Recombinant Bovine Enterovirus in China: Insights from Phylogenetic and Temporal Analysis

Bovine enteroviruses (BEVs) are emerging pathogens with poorly understood evolutionary dynamics and zoonotic potential. Here, we report the discovery of a novel recombinant BEV strain, HeN-2022, isolated from cattle in China. Genomic analysis revealed that HeN-2022 is a primary hybrid of BEV-E1 (VG527, Ireland) and BEV-E4 (GX1901, China), with recombination breakpoints in the VP1 gene and 5' UTR. Divergence dating traced its origin to 1991, predating closely related strains. Experimental infection in sheep demonstrated asymptomatic viral shedding (peak at 5 dpi) and robust neutralizing antibody responses, highlighting the potential cross-species adaptability. These findings underscore recombination as a potential key driver of BEV evolution and emphasize the need for global surveillance to address emerging livestock pathogens.

Enterovirus E infections in goats with respiratory disease

BACKGROUND

Enterovirus E (EV-E) has been called bovine enterovirus and has been found in both healthy animals and sick animals. To date, the pathogenicity of EV-E in goats is still unclear, and the natural infection of EV-E in goats has not been reported in China. In this study, natural infections of EV-E in goat herds were reported in China.

RESULTS

From March 2023 to April 2023, an emerging respiratory disease affected goats in 12 backyard farms in Henan Province, central China. To investigate the pathogens associated with the disease, samples were collected: sick group included six lung samples from dead goats and 68 nasal swabs and 68 blood samples from sick goats; health group included 36 nasal swabs and 36 blood samples from healthy goats in the same farms; control group included 15 nasal swabs and 15 blood samples from healthy goats in five different farms. Then, these samples were analysed by serology, isolation and molecular detection methods. By molecular detection, 83.3% (5/6) of lung samples, 51.5% (35/68) of nasal samples, and 33.8% (23/68) of blood samples were positive for EV-E in sick group. Four complete EV-E genomes were successfully sequenced and analysed. Compared with genomic sequences of EV A-J, at the nucleotide level the similarities of VP1, P1 and polyprotein genes of the 4 strains were 35.3% to 80.4%, 40.2% to 79.3%, and 49.5% to 82.0%, respectively. At the amino acid level, the similarities of VP1, P1 and Polyprotein were 38.4% to 87.1%, 42.9% to 88.7%, and 51.4% to 91.6%, respectively. Based on the VP1, P1 and Polyprotein sequences, the four strains were clustered with the subtype EV-E4 isolates. In addition, no recombinant event was observed in the four strains in our work by RDP analysis.

CONCLUSIONS

This is the first molecular evidence of natural infection of genotype E4 in goats with respiratory disease in China. Greater prevention and control measures should be carried out for this disease.

Molecular characterization of enteroviruses circulating among pigs and goats in two Central African countries, Cameroon and the Central African Republic

To date, data on animal enteroviruses (EVs) are scarce, especially in Central Africa. The aim of this study was to characterize EVs among pigs and goats in Cameroon and the Central African Republic (CAR). A total of 226 pig and goat faecal samples collected in two previous studies carried out in Cameroon and CAR were pooled and screened with molecular assays targeting EV-Es, EV-Fs and EV-Gs. EV genomes were amplified by RT-PCR and their sequences were obtained by Illumina sequencing and de novo assembly. Based on the capsid sequences, 27 EV-G sequences were identified and assigned to 11 virus types, while no EV-E or EV-F was observed. Phylogenetic analysis revealed that the EV-Gs detected in Central Africa do not form specific clusters compared to EV-Gs previously reported in other continents. This suggests a worldwide circulation of EV-Gs, which is likely due to the massive international trade of live animals. One human EV, EV-C99, which belongs to the species Enterovirus C, was detected in pigs. This is the third detection of such an event in a similar context, reinforcing the hypothesis that some EV-Cs could be infecting pigs. Our work provides new data on the genetic diversity of EVs circulating among domestic animals in Central Africa.

Immunogenicity analysis based on VP1 and VP2 proteins of bovine enterovirus

Bovine enterovirus (BEV) infection manifests as a spectrum of clinical signs affecting the respiratory, gastrointestinal, and reproductive systems in cattle. Outbreaks of this disease results in large economic losses to the bovine industry worldwide. Currently there are no efficacious vaccines and medicines to prevent BEV infection. In the present study, reverse transcription-polymerase chain reaction was used to amplify the VP1 and VP2 genes of BEV, enabling the synthesis of a chimeric recombinant protein which contained partial sequences from both proteins. Subsequently, the emulsified purified proteins with Freund's adjuvant were used for triple-fold immunization of 4-week-old Institute of Cancer Research (ICR) mice. The mice were subsequently subjected to a challenge assay which elicited an immune response that was characterized by elevated titers of BEV-specific neutralizing antibodies. Notably, the results showed that the purification of pET32a-VP1 and pET32a-VP2 proteins markedly curtailed virus excretion and mitigated the histopathological damage usually associated with BEV infections. These were observed in the small intestines, kidneys and brain in infected animals. It also alleviated clinical symptoms such as hypothermia and weight loss. In summary, this study offers a theoretical and practical basis for BEV vaccine development.

Molecular Epidemiology of Bovine Enteroviruses and Genome Characterization of Two Novel Bovine Enterovirus Strains in Guangxi, China

Bovine enterovirus (BEV) is a highly infectious pathogen that may cause respiratory and gastrointestinal disease outbreaks in cattle. This study aimed to investigate the prevalence and genetic characteristics of BEVs in Guangxi Province, China. A total of 1,168 fecal samples from 97 different bovine farms were collected between October 2021 and July 2022 in Guangxi Province, China. BEV was confirmed using a reverse transcription-PCR (RT-PCR) method targeting the 5' untranslated region (UTR), and isolates were genotyped by sequencing their genomes. The nearly complete genome sequences of eight BEV strains showing cytopathic effects in MDBK cells were determined and analyzed. In total, 125 (10.7%) of 1,168 fecal samples were positive for BEV. BEV infection was significantly associated with farming patterns and clinical symptoms (P < 0.05; odds ratio [OR] > 1). Molecular characterization indicated that five BEV strains from this study belonged to EV-E2 and one strain to EV-E4. Two BEV strains (GXNN2204 and GXGL2215) could not be assigned to a known type. Strain GXGL2215 showed the closest genetic relationship with GX1901 (GenBank accession number MN607030; China) in its VP1 (67.5%) and P1 (74.7%) and with NGR2017 (MH719217; Nigeria) in its polyprotein (72.0%). It was also close to the EV-E4 strain GXYL2213 from this study when the complete genome (81.7%) was compared. Strain GXNN2204 showed the closest genetic relationship with Ho12 (LC150008; Japan) in the VP1 (66.5%), P1 (71.6%), and polyprotein (73.2%). Genome sequence analysis suggested that strains GXNN2204 and GXGL2215 originated from the genomic recombination of EV-E4 and EV-F3 and EV-E2 and EV-E4, respectively. This study reports the cocirculation of multiple BEV types and the identification of two novel BEV strains in Guangxi, China, and it will provide further insights into the epidemiology and evolution of BEV in China. IMPORTANCE Bovine enterovirus (BEV) is a pathogen that causes intestinal, respiratory, and reproductive disease infections in cattle. This study reports on the widespread prevalence and biological characteristics of the different BEV types which currently exist in Guangxi Province, China. It also provides a reference for the study of the prevalence of BEV in China.

Identification of a novel polyomavirus from a marsupial host

We report the identification and analysis of a full sequence of a novel polyomavirus from a brushtail possum (Trichosurus vulpecula ) termed possum polyomavirus (PPyV). The sequence was obtained from the next-generation sequencing assembly during an investigation into the aetiological agent for a neurological disease of possums termed wobbly possum disease (WPD), but the virus was not aetiologically involved in WPD. The PPyV genome was 5,224 nt long with the organisation typical for polyomaviruses, including early (large and small T antigens) and late (Viral Protein 1 (VP1), VP2, and VP3) coding regions separated by the non-coding control region of 465 nt. PPyV clustered with betapolyomaviruses in the WUKI clade but showed less than 60 per cent identity to any of the members of this clade. We propose that PPyV is classified within a new species in the genus Betapolyomavirus . These data add to our limited knowledge of marsupial viruses and their evolution.

Isolation and Identification of Two Clinical Strains of the Novel Genotype Enterovirus E5 in China

Most enterovirus (EV) infections are subclinical but, occasionally, can cause severe and potentially fatal diseases in humans and animals. Currently, EVs are divided into 12 types (A to L) based on phylogenetic analysis and on their natural hosts. Bovine enterovirus (BEV) is an essential member of the enterovirus belonging to the types E and F that attacks cattle as its natural host and causes clinical disorders in the digestive, respiratory, and reproductive tracts. In 2020, several dairy farms in China experienced cow mortality with acute clinical signs, including fever, and diarrhea. In these cases, GX20-1 and JS20-1 virus strains were isolated and sequenced. Cellular adaptation of these two strains showed efficient replications on Madin-Darby bovine kidney (MDBK) cells and produced a significant cytopathogenic effect (CPE). However, on baby hamster kidney (BHK-21) and Vero cells, viral replication was inefficient and did not produce CPE. As noted in comparative genomics analysis, these two strains showed distant evolutionary relationships with the well-known E1 to E4 and F1 to F4 subtypes of BEV and high sequence identities with the candidate type Enterovirus E5, a novel genotype recently identified based on the genomic data of three strains, including the GX20-1 and JS20-1 strains. This study provides the first evidence of a novel genotype bovine enterovirus infection in Chinese cattle herds, a potential threat to the cattle industry in China.

IMPORTANCE Bovine enterovirus (BEV) is a cattle-infecting pathogen. This study is the first report of natural infection of a novel genotype of enterovirus in herds of cattle in China. The homology of the novel enterovirus is far different from the structural protein of other enteroviruses and has different cellular adaptations. This study provides a reference for the biological characteristics and prevalence of the novel enterovirus in Chinese cattle populations.

Cryo-EM Structure of a Possum Enterovirus

Enteroviruses (EVs) represent a substantial concern to global health. Here, we present the cryo-EM structure of a non-human enterovirus, EV-F4, isolated from the Australian brushtail possum to assess the structural diversity of these picornaviruses. The capsid structure, determined to ~3 Å resolution by single particle analysis, exhibits a largely smooth surface, similar to EV-F3 (formerly BEV-2). Although the cellular receptor is not known, the absence of charged residues on the outer surface of the canyon suggest a different receptor type than for EV-F3. Density for the pocket factor is clear, with the entrance to the pocket being smaller than for other enteroviruses.

Isolation and Identification of Type F Bovine Enterovirus from Clinical Cattle with Diarrhoea

Recently, bovine enterovirus (BEV) has caused several respiratory and gastrointestinal diseases outbreaks in cattle. Monitoring the epidemiological and pathogenic characteristics of this virus is crucial to controlling its spread. We isolated a BEV strain with typical cytopathic effects from the faeces of cows with significant diarrhoeal symptoms in China and observed the viral particles within 20–30 nm through transmission electron microscopy. Then, we designated this strain as HB19-1 in this study. The multistep growth curves showed that the virus propagated well in the MDBK cells. Molecular genetic analysis of VP1 indicated that HB19-1 belonged to the BEV-F1 group. Although the challenged ICR mice did not exhibit typical disease symptoms in animal infection assay, we observed significant pathological damage in the lungs, intestines, and muscle tissues. In summary, we isolated a BEV strain HB19-1 causing severe diarrhoea in cattle and proposed reinforcing the epidemiological surveillance of this virus.

Peptide Presentations of Marsupial MHC Class I Visualize Immune Features of Lower Mammals Paralleled with Bats

Marsupials are one of three major mammalian lineages that include the placental eutherians and the egg-laying monotremes. The marsupial brushtail possum is an important protected species in the Australian forest ecosystem. Molecules encoded by the MHC genes are essential mediators of adaptive immune responses in virus-host interactions. Yet, nothing is known about the peptide presentation features of any marsupial MHC class I (MHC I). This study identified a series of possum MHC I Trvu-UB*01:01 binding peptides derived from wobbly possum disease virus (WPDV), a lethal virus of both captive and feral possum populations, and unveiled the structure of marsupial peptide/MHC I complex. Notably, we found the two brushtail possum-specific insertions, the 3-aa Ile⁵²Glu⁵³Arg⁵⁴ and 1-aa Arg¹⁵⁴ insertions are located in the Trvu-UB*01:01 peptide binding groove (PBG). The 3-aa insertion plays a pivotal role in maintaining the stability of the N terminus of Trvu-UB*01:01 PBG. This aspect of marsupial PBG is unexpectedly similar to the bat MHC I Ptal-N*01:01 and is shared with lower vertebrates from elasmobranch to monotreme, indicating an evolution hotspot that may have emerged from the pathogen-host interactions. Residue Arg¹⁵⁴ insertion, located in the α2 helix, is available for TCR recognition, and it has a particular influence on promoting the anchoring of peptide WPDV-12. These findings add significantly to our understanding of adaptive immunity in marsupials and its evolution in vertebrates. Our findings have the potential to impact the conservation of the protected species brushtail possum and other marsupial species.

Experimental immunization of mice with a recombinant bovine enterovirus vaccine expressing BVDV E0 protein elicits a long-lasting serologic response

Background

Bovine viral diarrhea virus (BVDV) is a cause of substantial economic loss to the cattle industry worldwide, and there are currently no effective treatment or preventive measures. Bovine enterovirus (BEV) has a broad host range with low virulence and is a good candidate as a viral vaccine vector. In this study, we explored new insertion sites for the expression of exogenous genes in BEV, and developed a recombinant infectious cDNA clone for BEV BJ101 strain expressing BVDV E0 protein.

Methods

A recognition site for the viral proteinase 3C^pro was inserted in the GpBSK-BEV plasmid at the 2C/3A junction by overlapping PCR. Subsequently, the optimized full-length BVDV E0 gene was inserted to obtain the recombinant infectious plasmid GpBSK-BEV-E0. The rescued recombinant virus was obtained by transfection with linearized plasmid. Expression of BVDV E0 in the recombinant virus was confirmed by PCR, western blotting, and immunofluorescence analysis, and the genetic stability was tested in MDBK cells over 10 passages. We further tested the ability of the recombinant virus to induce an antibody response in mice infected with BVDV and immunized them with the recombinant virus and parental strain.

Results

The rescued recombinant virus rBEV-E0 was identified and confirmed by western blot and indirect immunofluorescence. The sequencing results showed that the recombinant virus remained stable for 10 passages without genetic changes. There was also no significant difference in growth dynamics and plaque morphology between the recombinant virus and parental virus. Mice infected with both recombinant and parental viruses produced antibodies against BEV VP1, while the recombinant virus also induced antibodies against BVDV E0.

Conclusion

A new insertion site in the BEV vector can be used for the prevention and control of both BEV and BVDV, providing a useful tool for future research on the development of viral vector vaccines.

A study regarding bovine enterovirus type 1 infection in domestic animals and humans: An evaluation from the zoonotic aspect

Bovine enteroviruses (BEV) are members of Enterovirus genus of the family Picornaviridae. BEV1 has a broad host spectrum, including humans. The virus usually causes subclinical infection, but fatal/severe cases have also been reported in different animal species. There is quite limited data regarding BEV1 in humans. The purpose of this study is to investigate human infection and to identify possible risk factors for viral exposure. For this purpose, blood serum samples (n=1,526) were collected from a city center and nearby villagers simultaneously from humans and farm animals in Elazig province in Eastern Anatolia. As a result of serum neutralisation test, BEV1 specific antibody presence detected in cattle was 85.3% (163/191), 73.5% in donkeys (64/87), 71.8% in goats (115/160), 46.5% in sheep (93/200), 43.9% in horses (40/91), 41.3% in dogs (19/46) and 33% in humans (248/751). Although a high contamination potential was mentioned for people living in rural areas, it was determined that infection rates in rural areas (31.6%) and urban centers (32.2%) were very close. There was no difference according to sex. Viral exposure is higher in the 40 to 70 age range. In addition, the serological evidence of the infection in donkeys was identified for the first time with this study.

Molecular Identification of Enteroviruses from Cattle and Goat Feces and Environment in Thailand

The identification and characterization of viruses of the genus Enterovirus in healthy and infected livestock, including cattle and goats, have been increasing. Enterovirus E (EV-E) and Enterovirus F (EV-F) are commonly found in cattle, whereas Enterovirus G (EV-G) is found in goats. In this study, molecular and phylogenetic analyses were performed to determine the prevalence of EVs in cattle and goat feces from Kanchanaburi Province, Thailand. The presence of EVs in water samples and the feces of other animals collected from the areas surrounding cattle and goat farms was also investigated. By use of 5'-untranslated region (5' UTR) real-time reverse transcription-PCR (RT-PCR), EVs were detected in 39.5% of cattle samples, 47% of goat samples, 35.3% of water samples, and one pool of chicken feces. Phylogenetic analysis revealed the presence of EV-E and EV-F in cattle, EV-E and EV-G in goats, and EV-F in water samples and chicken feces. Analysis of enteroviral VP1 sequences from cattle revealed that the EV-E genotypes circulating in the study region were EV-E1, with a possible new genotype that is closely related to EV-E2. Analysis of enteroviral VP1 sequences from goats suggested the circulation of EV-G5 and a possible new genotype that is closely related to EV-G20. Sequence analyses also suggested that although the VP1 sequences from goats were closely related to those of EV-G, which were considered porcine enterovirus sequences, their 5' UTRs form a separated cluster with sequences of sheep and goat origin, suggesting a new classification of the ovine/caprine-specific enterovirus group.IMPORTANCE Possible new EV-E and EV-G genotypes were identified for EVs detected in this study. The EV-E viruses were also successfully isolated from MDBK cells. The goat EV sequence analysis suggested the presence of an ovine/caprine-specific EV group that is different from EV-G of porcine origin. The significance of our research is that it identifies and characterizes possible novel EVs, thereby indicating that enteroviruses in animals are continually evolving. The facts that enteroviruses can persist in the environment, contaminate it for long periods, and be transmitted between animals raise serious concerns regarding this group of viruses as emerging livestock pathogens.

Metagenomic discovery and co-infection of diverse wobbly possum disease viruses and a novel hepacivirus in Australian brushtail possums

BACKGROUND

Australian brushtail possums (Trichosurus vulpecula) are an introduced pest species in New Zealand, but native to Australia where they are protected for biodiversity conservation. Wobbly possum disease (WPD) is a fatal neurological disease of Australian brushtail possums described in New Zealand populations that has been associated with infection by the arterivirus (Arteriviridae) wobbly possum disease virus (WPDV-NZ). Clinically, WPD-infected possums present with chronic meningoencephalitis, choroiditis and multifocal neurological symptoms including ataxia, incoordination, and abnormal gait.

METHODS

We conducted a retrospective investigation to characterise WPD in native Australian brushtail possums, and used a bulk meta-transcriptomic approach (i.e. total RNA-sequencing) to investigate its potential viral aetiology. PCR assays were developed for case diagnosis and full genome recovery in the face of extensive genetic variation.

RESULTS

We identified genetically distinct lineages of arteriviruses from archival tissues of WPD-infected possums in Australia, termed wobbly possum disease virus AU1 and AU2. Phylogenetically, WPDV-AU1 and WPDV-AU2 shared only ~ 70% nucleotide similarity to each other and the WPDV-NZ strain, suggestive of a relatively ancient divergence. Notably, we also identified a novel and divergent hepacivirus (Flaviviridae) - the first in a marsupial - in both WPD-infected and uninfected possums, indicative of virus co-infection.

CONCLUSIONS

We have identified marsupial-specific lineages of arteriviruses in mainland Australia that are genetically distinct from that in New Zealand, in some cases co-infecting animals with a novel hepacivirus. Our study provides new insight into the hidden genetic diversity of arteriviruses, the capacity for virus co-infection, and highlights the utility of meta-transcriptomics for disease investigation in a One Health context.

Viral RNA load and histological changes in tissues following experimental infection with an arterivirus of possums (wobbly possum disease virus)

Tissues from Australian brushtail possums (Trichosurus vulpecula) that had been experimentally infected with wobbly possum disease (WPD) virus (WPDV) were examined to elucidate pathogenesis of WPDV infection. Mononuclear inflammatory cell infiltrates were present in livers, kidneys, salivary glands and brains of WPD-affected possums. Specific staining was detected by immunohistochemistry within macrophages in the livers and kidneys, and undefined cell types in the brains. The highest viral RNA load was found in macrophage-rich tissues. The detection of viral RNA in the salivary gland, serum, kidney, bladder and urine is compatible with transmission via close physical contact during encounters such as fighting or grooming, or by contact with an environment that has been contaminated with saliva or urine. Levels of viral RNA remained high in all tissues tested throughout the study, suggesting that on-going virus replication and evasion of the immune responses may be important in the pathogenesis of disease.

Identification of a novel bovine enterovirus possessing highly divergent amino acid sequences in capsid protein

BACKGROUND

Bovine enterovirus (BEV) belongs to the species Enterovirus E or F, genus Enterovirus and family Picornaviridae. Although numerous studies have identified BEVs in the feces of cattle with diarrhea, the pathogenicity of BEVs remains unclear. Previously, we reported the detection of novel kobu-like virus in calf feces, by metagenomics analysis. In the present study, we identified a novel BEV in diarrheal feces collected for that survey. Complete genome sequences were determined by deep sequencing in feces. Secondary RNA structure analysis of the 5' untranslated region (UTR), phylogenetic tree construction and pairwise identity analysis were conducted.

RESULTS

The complete genome sequences of BEV were genetically distant from other EVs and the VP1 coding region contained novel and unique amino acid sequences. We named this strain as BEV AN12/Bos taurus/JPN/2014 (referred to as BEV-AN12). According to genome analysis, the genome length of this virus is 7414 nucleotides excluding the poly (A) tail and its genome consists of a 5'UTR, open reading frame encoding a single polyprotein, and 3'UTR. The results of secondary RNA structure analysis showed that in the 5'UTR, BEV-AN12 had an additional clover leaf structure and small stem loop structure, similarly to other BEVs. In pairwise identity analysis, BEV-AN12 showed high amino acid (aa) identities to Enterovirus F in the polyprotein, P2 and P3 regions (aa identity ≥82.4%). Therefore, BEV-AN12 is closely related to Enterovirus F. However, aa sequences in the capsid protein regions, particularly the VP1 encoding region, showed significantly low aa identity to other viruses in genus Enterovirus (VP1 aa identity ≤58.6%). In addition, BEV-AN12 branched separately from Enterovirus E and F in phylogenetic trees based on the aa sequences of P1 and VP1, although it clustered with Enterovirus F in trees based on sequences in the P2 and P3 genome region.

CONCLUSIONS

We identified novel BEV possessing highly divergent aa sequences in the VP1 coding region in Japan. According to species definition, we proposed naming this strain as "Enterovirus K", which is a novel species within genus Enterovirus. Further genomic studies are needed to understand the pathogenicity of BEVs.

Genetic variations in regions of bovine and bovine-like enteroviral 5'UTR from cattle, Indian bison and goat feces

Background

Bovine enteroviruses (BEV) are members of the genus Enterovirus in the family Picornaviridae. They are predominantly isolated from cattle feces, but also are detected in feces of other animals, including goats and deer. These viruses are found in apparently healthy animals, as well as in animals with clinical signs and several studies reported recently suggest a potential role of BEV in causing disease in animals. In this study, we surveyed the presence of BEV in domestic and wild animals in Thailand, and assessed their genetic variability.

Methods

Viral RNA was extracted from fecal samples of cattle, domestic goats, Indian bison (gaurs), and deer. The 5’ untranslated region (5’UTR) was amplified by nested reverse transcription-polymerase chain reaction (RT-PCR) with primers specific to BEV 5’UTR. PCR products were sequenced and analyzed phylogenetically using the neighbor-joining algorithm to observe genetic variations in regions of the bovine and bovine-like enteroviral 5’UTR found in this study.

Results

BEV and BEV-like sequences were detected in the fecal samples of cattle (40/60, 67 %), gaurs (3/30, 10 %), and goats (11/46, 24 %). Phylogenetic analyses of the partial 5’UTR sequences indicated that different BEV variants (both EV-E and EV-F species) co-circulated in the domestic cattle, whereas the sequences from gaurs and goats clustered according to the animal species, suggesting that these viruses are host species-specific.

Conclusions

Varieties of BEV and BEV-like 5’UTR sequences were detected in fecal samples from both domestic and wild animals. To our knowledge, this is the first report of the genetic variability of BEV in Thailand.

Identification of a novel enterovirus E isolates HY12 from cattle with severe respiratory and enteric diseases

In this study, a virus strain designated as HY12 was isolated from cattle with a disease of high morbidity and mortality in Jilin province. Biological and physiochemical properties showed that HY12 isolates is cytopathic with an extremely high infectivity. HY12 is resistant to treatment of organic solvent and acid, and unstable at 60°C for 1 h. Electron microscopy observation revealed the virus is an approximately 22–28 nm in diameter. The complete genome sequence of HY12 consists of 7416 nucleotides, with a typical picornavirus genome organization including a 5′-untranslated region (UTR), a large single ORF encoding a polyprotein of 2176 amino acids, and a 3′-UTR. Phylogenetic analysis clustered HY12 isolates to a new serotype/genotype within the clade of enterovirus E (formerly BEV-A). Alignment analysis revealed a unique insertion of 2 amino acid residues (NF) at the C-terminal of VP1 protein between aa 825 and 826, and several rare mutations in VP1 and VP4 of HY12 isolates in relation to known bovine enterovirus (BEV) strains. This is the first report of an enterovirus E in China, which is potentially associated with an outbreak in cattle with severe respiratory and enteric diseases.

Discovery of a bovine enterovirus in alpaca

A cytopathic virus was isolated using Madin-Darby bovine kidney (MDBK) cells from lung tissue of alpaca that died of a severe respiratory infection. To identify the virus, the infected cell culture supernatant was enriched for virus particles and a generic, PCR-based method was used to amplify potential viral sequences. Genomic sequence data of the alpaca isolate was obtained and compared with sequences of known viruses. The new alpaca virus sequence was most similar to recently designated Enterovirus species F, previously bovine enterovirus (BEVs), viruses that are globally prevalent in cattle, although they appear not to cause significant disease. Because bovine enteroviruses have not been previously reported in U.S. alpaca, we suspect that this type of infection is fairly rare, and in this case appeared not to spread beyond the original outbreak. The capsid sequence of the detected virus had greatest homology to Enterovirus F type 1 (indicating that the virus should be considered a member of serotype 1), but the virus had greater homology in 2A protease sequence to type 3, suggesting that it may have been a recombinant. Identifying pathogens that infect a new host species for the first time can be challenging. As the disease in a new host species may be quite different from that in the original or natural host, the pathogen may not be suspected based on the clinical presentation, delaying diagnosis. Although this virus replicated in MDBK cells, existing standard culture and molecular methods could not identify it. In this case, a highly sensitive generic PCR-based pathogen-detection method was used to identify this pathogen.

Natural interspecies recombinant bovine/porcine enterovirus in sheep

Members of the genus Enterovirus (family Picornaviridae) are believed to be common and widespread among humans and different animal species, although only a few enteroviruses have been identified from animal sources. Intraspecies recombination among human enteroviruses is a well-known phenomenon, but only a few interspecies examples have been reported and, to our current knowledge, none of these have involved non-primate enteroviruses. In this study, we report the detection and complete genome characterization (using RT-PCR and long-range PCR) of a natural interspecies recombinant bovine/porcine enterovirus (ovine enterovirus type 1; OEV-1) in seven (44 %) of 16 faecal samples from 3-week-old domestic sheep (Ovis aries) collected in two consecutive years. Phylogenetic analysis of the complete coding region revealed that OEV-1 (ovine/TB4-OEV/2009/HUN; GenBank accession no. JQ277724) was a novel member of the species Porcine enterovirus B (PEV-B), implying the endemic presence of PEV-B viruses among sheep. However, the 5′ UTR of OEV-1 showed a high degree of sequence and structural identity to bovine enteroviruses. The presumed recombination breakpoint was mapped to the end of the 5′ UTR at nucleotide position 814 using sequence and SimPlot analyses. The interspecies-recombinant nature of OEV-1 suggests a closer relationship among bovine and porcine enteroviruses, enabling the exchange of at least some modular genetic elements that may evolve independently.

Toward genetics-based virus taxonomy: comparative analysis of a genetics-based classification and the taxonomy of picornaviruses

Virus taxonomy has received little attention from the research community despite its broad relevance. In an accompanying paper (C. Lauber and A. E. Gorbalenya, J. Virol. 86:3890-3904, 2012), we have introduced a quantitative approach to hierarchically classify viruses of a family using pairwise evolutionary distances (PEDs) as a measure of genetic divergence. When applied to the six most conserved proteins of the Picornaviridae, it clustered 1,234 genome sequences in groups at three hierarchical levels (to which we refer as the "GENETIC classification"). In this study, we compare the GENETIC classification with the expert-based picornavirus taxonomy and outline differences in the underlying frameworks regarding the relation of virus groups and genetic diversity that represent, respectively, the structure and content of a classification. To facilitate the analysis, we introduce two novel diagrams. The first connects the genetic diversity of taxa to both the PED distribution and the phylogeny of picornaviruses. The second depicts a classification and the accommodated genetic diversity in a standardized manner. Generally, we found striking agreement between the two classifications on species and genus taxa. A few disagreements concern the species Human rhinovirus A and Human rhinovirus C and the genus Aphthovirus, which were split in the GENETIC classification. Furthermore, we propose a new supergenus level and universal, level-specific PED thresholds, not reached yet by many taxa. Since the species threshold is approached mostly by taxa with large sampling sizes and those infecting multiple hosts, it may represent an upper limit on divergence, beyond which homologous recombination in the six most conserved genes between two picornaviruses might not give viable progeny.

Genetic variation of coat protein gene among the isolates of Rice tungro spherical virus from tungro-endemic states of the India

Rice tungro disease, one of the major constraints to rice production in South and Southeast Asia, is caused by a combination of two viruses: Rice tungro spherical virus (RTSV) and Rice tungro bacilliform virus (RTBV). The present study was undertaken to determine the genetic variation of RTSV population present in tungro endemic states of Indian subcontinent. Phylogenetic analysis based on coat protein sequences showed distinct divergence of Indian RTSV isolates into two groups; one consisted isolates from Hyderabad (Andhra Pradesh), Cuttack (Orissa), and Puducherry and another from West Bengal, Coimbatore (Tamil Nadu), and Kanyakumari (Tamil Nadu). The results obtained from phylogenetic study were further supported with the SNPs (single nucleotide polymorphism), INDELs (insertion and deletion) and evolutionary distance analysis. In addition, sequence difference count matrix revealed 2-68 nucleotides differences among all the Indian RTSV isolates taken in this study. However, at the protein level these differences were not significant as revealed by Ka/Ks ratio calculation. Sequence identity at nucleotide and amino acid level was 92-100% and 97-100%, respectively, among Indian isolates of RTSV. Understanding of the population structure of RTSV from tungro endemic regions of India would potentially provide insights into the molecular diversification of this virus.

New recognition of Enterovirus infections in bottlenose dolphins (Tursiops truncatus)

An enterovirus was cultured from an erosive tongue lesion of a bottlenose dolphin (Tursiops truncatus). The morphology of virions on negative staining electron microscopy was consistent with those of enteroviruses. Analysis of 2613 bp of the polyprotein gene identified the isolate as a novel enterovirus strain, tentatively named bottlenose dolphin enterovirus (BDEV), that nests within the species Bovine enterovirus. Serologic evidence of exposure to enteroviruses was common in both free-ranging and managed collection dolphins. Managed collection dolphins were more likely to have high antibody levels, although the highest levels were reported in free-ranging populations. Associations between enterovirus antibody levels, and age, sex, complete blood counts, and clinical serum biochemistries were explored. Dolphins with higher antibody levels were more likely to be hyperproteinemic and hyperglobulinemic.

Oral challenge of brushtail possums (Trichosurus vulpecula) with possum enteroviruses: clinical observation, antibody response and virus excretion in faeces

AIM

To investigate the pathogenesis of two cytopathic enteroviruses, W1 and W6, isolated from possums, to evaluate their potential as vectors for biological management of possums.

METHODS

Possums (n=10) were fed 1 x 107 median tissue culture infectious doses (TCID50) of either the W1 strain (Possums 1-5) or W6 strain (Possums 6-10), while controls (n=2, Possums 11 and 12) were fed uninfected cell culture medium. Blood samples were collected from all possums on Days -1, 2, 7, 14, 21 and 34 or 35 post-inoculation (p.i.), and bodyweight and rectal temperatures were measured on the same days. Virus specific antibodies were determined using virus neutralisation tests (VNTs). Faeces were collected on Days -1, 2, 7, 9, 14, 16, 21, 28 and 34 or 35 p.i., and the presence of W1 and W6 virus in faeces was determined using cell culture and reverse transcriptase-polymerase chain reaction (RT-PCR). Possums were euthanised on Day 34 or 35, and ileal Peyer's patches were collected for detection of virus using RT-PCR.

RESULTS

No diarrhoea or significant changes in rectal temperature or loss of bodyweight were observed in virus-inoculated possums during the study period. Virus-neutralising antibodies were detected using VNTs in 2/5 and 3/5 possums exposed to the W1 and W6 strain, respectively. Excretion of virus in faeces was detected in 6/10 virus-inoculated possums, from as early as Day 4 p.i.; virus excretion in faeces was transient in some and persistent in other possums up to the time of euthanasia. The viruses were detected in 3/10 virus-inoculated possums following necropsy, but were not detected using RT-PCR in sera collected on Days 2 and 7, nor in Peyer's patches of virus-inoculated possums collected on Day 34 or 35.

CONCLUSIONS

Possum enteroviruses W1 and W6 established an asymptomatic infection in the gastrointestinal tract (GIT) in a proportion of challenged possums. A virus-specific antibody response was elicited in infected possums, which excreted the virus in faeces for up to 35 days p.i. The absence of noticeable adverse effects in enterovirus-infected possums is an advantageous characteristic for candidate vectors on animal welfare grounds.