Bovine kobuvirus-A comprehensive review

Bovine kobuvirus (BKV) is a single-stranded, positive sense, non-enveloped RNA virus in genus Kobuvirus of family Picornavirus. BKV was first identified in the culture media of HeLa cell containing calf serum in 2003. Since then, BKV has been detected in 13 countries of four different continents, suggesting widespread in the world. Herein, we review the detection and genomic characterization of BKV in 13 countries. All studies tested bovine faecal samples for BKV. These studies provide evidence that BKV might be a causative agent for neonatal calf diarrhoea. Therefore, further efforts including animal challenge study are urgently needed to unveil the pathogenicity of BKV.

Whole genome analysis of Aichivirus A, isolated from a child, suffering from gastroenteritis, in Pakistan

Viruses are the primary cause of acute gastroenteritis in children all over the world. Understanding the emergence and genetic variation of these viruses may help to prevent infections. Aichivirus (AiV) is a member of the Kobuvirus genus, which currently contains six officially recognized species: Aichivirus A-F. The species AiV A contains six types including Aichivirus 1 (AiV 1) and eventually, three genotypes have been identified in the human AiV 1 (named A to C). The present study describes the identification and sequencing of the polyprotein gene of a human AiV 1 strain PAK419 via NGS in Pakistani children with acute gastroenteritis. Our study strain PAK419 was classified as AiV 1 genotype A, most commonly found in Japan and Europe, and closely related to non-Japanese and European strains on the phylogenetic tree. PAK419 showed 95-98 % nucleotide sequence identity with strains isolated from Ethiopia (ETH/2016/P4), Australia (FSS693) and China (Chshc7). On phylogenetic observation PAK419 formed a distinct cluster in the AiV 1 genotype A with the above mentioned and other human AiV strains detected around the world (Germany, Brazil, Japan, Thailand, Korea and Vietnam). The data clearly showed that Pakistani AiV strains and human strains identified from all over the world are distinct from Aichivirus strains found in bovine, swine, canine, feline, caprine, ferret, bat, and environmental samples. The distinguishing characteristics of the AiV genome showed a lower probability of inter-genotypic recombination events, which may support the lack of AiV serotypes. PAK419 also had a high content of C nucleotide (37.4 %), as found in previous studies, which could also restrict the possible genetic variation of AiV. This study demonstrate the power of NGS in uncovering unknown gastroenteric etiological agents circulating in the population.

Characterization of a novel picornavirus isolated from moribund aquacultured clownfish

Over the last decade, a number of USA aquaculture facilities have experienced periodic mortality events of unknown aetiology in their clownfish (Amphiprion ocellaris). Clinical signs of affected individuals included lethargy, altered body coloration, reduced body condition, tachypnea, and abnormal positioning in the water column. Samples from outbreaks were processed for routine parasitological, bacteriological, and virological diagnostic testing, but no consistent parasitic or bacterial infections were observed. Histopathological evaluation revealed individual cell necrosis and mononuclear cell inflammation in the branchial cavity, pharynx, oesophagus and/or stomach of four examined clownfish, and large basophilic inclusions within the pharyngeal mucosal epithelium of one fish. Homogenates from pooled external and internal tissues from these outbreaks were inoculated onto striped snakehead (SSN-1) cells for virus isolation and cytopathic effects were observed, resulting in monolayer lysis in the initial inoculation and upon repassage. Transmission electron microscopy of infected SSN-1 cells revealed small round particles (mean diameter=20.0-21.7 nm) within the cytoplasm, consistent with the ultrastructure of a picornavirus. Full-genome sequencing of the purified virus revealed a novel picornavirus most closely related to the bluegill picornavirus and other members of the genus Limnipivirus. Additionally, pairwise protein alignments between the clownfish picornavirus (CFPV) and other known members of the genus Limnipivirus yielded results in accordance with the current International Committee on Taxonomy of Viruses criteria for members of the same genus. Thus, CFPV represents a proposed new limnipivirus species. Future experimental challenge studies are needed to determine the role of CFPV in disease.

Discovery of Lanama Virus, a Distinct Member of Species Kunsagivirus C (Picornavirales: Picornaviridae), in Wild Vervet Monkeys (Chlorocebus pygerythrus)

We report the discovery and sequence-based molecular characterization of a novel virus, lanama virus (LNMV), in blood samples obtained from two wild vervet monkeys (Chlorocebus pygerythrus), sampled near Lake Nabugabo, Masaka District, Uganda. Sequencing of the complete viral genomes and subsequent phylogenetic analysis identified LNMV as a distinct member of species Kunsagivirus C, in the undercharacterized picornavirid genus Kunsagivirus.

Comparison of historical and contemporary isolates of Senecavirus A

Senecavirus A (SVA) was discovered as a cell culture contaminant in 2002, and multiple attempts to experimentally reproduce disease were unsuccessful. Field reports of porcine idiopathic vesicular disease (PIVD) cases testing PCR positive for SVA in addition to outbreaks of PIVD in Brazil and the United States in 2015 suggested SVA was a causative agent, which has now been consistently demonstrated experimentally. Ease of experimental reproduction of disease with contemporary strains of SVA raised questions concerning the difficulty of reproducing vesicular disease with historical isolates. The following study was conducted to compare the pathogenicity of SVA between historical and contemporary isolates in growing pigs. Six groups of pigs (n = 8) were intranasally inoculated with the following SVA isolates: SVV001/2002, CAN/2011, HI/2012, IA/2015, NC/2015, SD/2015. All isolates induced vesicular disease in at least half of the inoculated pigs from each group. All pigs replicated virus as demonstrated by serum and/or swab samples positive for SVA by quantitative PCR. Pig sera tested by virus neutralization assay demonstrated cross-neutralizing antibodies against all viruses utilized in the study. Cross-neutralizing antibodies from pigs inoculated with historical isolates were lower than those pigs that were inoculated with contemporary isolates. Phylogenetic analysis revealed two clades with SVV001/2002 being in a separate clade compared to the other five isolates. Although differences in the infection kinetics and sequences of these six isolates were found, clinical presentation of vesicular disease was similar between both historical and contemporary isolates.

Characterization of Emerging Swine Viral Diseases through Oxford Nanopore Sequencing Using Senecavirus A as a Model

Emerging viral infectious diseases present a major threat to the global swine industry. Since 2015, Senecavirus A (SVA) has been identified as a cause of vesicular disease in different countries and is considered an emerging disease. Despite the growing concern about SVA, there is a lack of preventive and diagnostic strategies, which is also a problem for all emerging infectious diseases. Using SVA as a model, we demonstrated that Oxford Nanopore MinION sequencing could be used as a robust tool for the investigation and surveillance of emerging viral diseases. Our results identified that MinION sequencing allowed for rapid, unbiased pathogen detection at the species and strain level for clinical cases. SVA whole genome sequences were generated using both direct RNA sequencing and PCR-cDNA sequencing methods, with an optimized consensus accuracy of 94% and 99%, respectively. The advantages of direct RNA sequencing lie in its shorter turnaround time, higher analytical sensitivity and its quantitative relationship between input RNA and output sequencing reads, while PCR-cDNA sequencing excelled at creating highly accurate sequences. This study developed whole genome sequencing methods to facilitate the control of SVA and provide a reference for the timely detection and prevention of other emerging infectious diseases.

The Husavirus Posa-Like Viruses in China, and a New Group of Picornavirales

Novel posa-like viral genomes were first identified in swine fecal samples using metagenomics and were designated as unclassified viruses in the order Picornavirales. In the present study, nine husavirus strains were identified in China. Their genomes share 94.1–99.9% similarity, and alignment of these nine husavirus strains identified 697 nucleotide polymorphism sites across their full-length genomes. These nine strains were directly clustered with the Husavirus 1 lineage, and their genomic arrangement showed similar characteristics. These posa-like viruses have undergone a complex evolutionary process, and have a wide geographic distribution, complex host spectrum, deep phylogenetic divergence, and diverse genomic organizations. The clade of posa-like viruses forms a single group, which is evolutionarily distinct from other known families and could represent a distinct family within the Picornavirales. The genomic arrangement of Picornavirales and the new posa-like viruses are different, whereas the posa-like viruses have genomic modules similar to the families Dicistroviridae and Marnaviridae. The present study provides valuable genetic evidence of husaviruses in China, and clarifies the phylogenetic dynamics and the evolutionary characteristics of Picornavirales.

Proteome Analysis Reveals Syndecan 1 Regulates Porcine Sapelovirus Replication

Porcine sapelovirus A (PSV) is a single stranded, positive-sense, non-enveloped RNA virus that causes enteritis, pneumonia, polioencephalomyelitis, and reproductive disorders in pigs. Research on PSV infection and interaction with host cells is unclear. In this study, we applied tandem mass tag proteomics analysis to investigate the differentially expressed proteins (DEPs) in PSV-infected pig kidney (PK)-15 cells and explored the interactions between PSV and host cells. Here we mapped 181 DEPs, including 59 up-regulated and 122 down-regulated DEPs. Among them, osteopontin (SPP1), induced protein with tetratricopeptide repeats 5 (IFIT5), ISG15 ubiquitin-like modifier (ISG15), vinculin (VCL), and syndecan-1 (SDC1) were verified significantly changed using RT-qPCR. Additionally, overexpression of SDC1 promoted PSV viral protein (VP)1 synthesis and virus titer, and silencing of SDC1 revealed the opposite results. Our findings show that SDC1 is a novel host protein and plays crucial roles in regulating PSV replication.

Identification and genome characterization of a novel picornavirus from ducks in China

A novel picornavirus, referred to as Duck/FC22/China/2017, was isolated from breeding ducks in China and genetically characterized by conducting metagenomics studies. The complete genome consists of a single-stranded, positive-sense RNA made up of 7448 nucleotides (nt) and follows the common picornavirus genome layout: 5' UTR-VP0-VP3-VP1-2A-2B-2C-3A-3B-3C-3D-3' UTR. A typical type-IV internal ribosomal entry site and a conserved 'barbell-like' structure were identified in the 5' UTR and 3' UTR, respectively. The unique 6423-nt open reading frame was predicted to encode a 2141-amino-acid (aa) polyprotein precursor. A pairwise aa sequence identity comparison and phylogenetic analysis revealed that Duck/FC22/China/2017 is closely related to duck aalivirus, duck hepatitis A virus, turkey avisivirus, and red-crowned crane picornavirus.

Emerging Infectious Diseases of Rabbits

Recently, multiple infectious organisms have been identified as the cause of emerging diseases in lagomorphs. The most important of these emerging diseases is rabbit hemorrhagic disease virus (RHDV) type 2, a new variant with differences in pathogenicity to classical RHDV. Hepatitis E is considered an emerging zoonotic infectious disease, with widespread prevalence in many different rabbit populations. Mycobacteriosis has been recently reported in other captive domestic rabbit populations. This article provides a recent review of the published literature on emerging infectious diseases in rabbits, including farmed, laboratory, and pet rabbits, some of which have zoonotic potential.

Emergence and phylogenetic analysis of a novel Seneca Valley virus strain in the Guangxi Province of China

Senecavirus A (SVA), also known as Seneca Valley virus (SVV), is an emerging infectious pathogen which have been detected in swine herds from the Brazil, USA, Colombia, Thailand, Canada and some provinces in China, suggesting an increasing geographic distribution of this novel virus. Here, we isolated and characterized a SVV, designated SVA CH-GX-01-2018, thought to be responsible for typical vesicular lesions on the snouts and hooves of finishing pigs from a swine herds in Guangxi province, China, in August 2018. Phylogenetic analysis and sequence alignment indicated that this SVA CH-GX-01-2018 strain was closely related to the strains isolated in 2017 in Guangdong province, a neighboring province of Guangxi, South China, with 98.6% identity at the genome nucleotide level. Our findings characterized a novel SVV infection in pigs from South China and emphasize the importance of surveillance, reinforcing biosecurity measures and developing vaccines to prevent the spread of this viral pathogen.

Genetic and Biological Diversity of Porcine Sapeloviruses Prevailing in Zambia

Porcine sapelovirus (PSV) has been detected worldwide in pig populations. Although PSV causes various symptoms such as encephalomyelitis, diarrhea, and pneumonia in pigs, the economic impact of PSV infection remains to be determined. However, information on the distribution and genetic diversity of PSV is quite limited, particularly in Africa. In this study, we investigated the prevalence of PSV infection in Zambia and characterized the isolated PSVs genetically and biologically. We screened 147 fecal samples collected in 2018 and found that the prevalences of PSV infection in suckling pigs and fattening pigs were high (36.2% and 94.0%, respectively). Phylogenetic analyses revealed that the Zambian PSVs were divided into three different lineages (Lineages 1–3) in the clade consisting of Chinese strains. The Zambian PSVs belonging to Lineages 2 and 3 replicated more efficiently than those belonging to Lineage 1 in Vero E6 and BHK cells. Bioinformatic analyses revealed that genetic recombination events had occurred and the recombination breakpoints were located in the L and 2A genes. Our results indicated that at least two biologically distinct PSVs could be circulating in the Zambian pig population and that genetic recombination played a role in the evolution of PSVs.

Bovine Kobuvirus in Calves with Diarrhea, United States

We detected bovine kobuvirus (BKV) in calves with diarrhea in the United States. The strain identified is related genetically to BKVs detected in other countries. Histopathologic findings also confirmed viral infection in 2 BKV cases. Our data show BKV is a potential causative agent for diarrhea in calves.

Bovine Astrovirus Surveillance in Uruguay Reveals High Detection Rate of a Novel Mamastrovirus Species

Viral infections affecting cattle lead to economic losses to the livestock industry worldwide, but little is known about the circulation, pathogenicity and genetic diversity of enteric bovine astrovirus (BoAstV) in America. The aim of this work was to describe the prevalence and genetic diversity of enteric BoAstV in dairy cattle in Uruguay. A total of 457 fecal and 43 intestinal contents from dairy calves were collected between July 2015 and May 2017 and tested by RT-PCR, followed by sequencing and phylogenetic analyses of the polymerase and capsid regions. Twenty-six percent (128/500) of the samples were positive. Three different species within the Mamastrovirus genus were identified, including Mamastrovirus 28, Mamastrovirus 33 (3 samples each) and an unclassified Mamastrovirus species (19 samples). The unclassified species was characterized as a novel Mamastrovirus species. BoAstV circulates in Uruguayan dairy cattle with a high genetic diversity. The eventual clinicopathological significance of enteric BoAstV infection in cattle needs further investigation.

Novel Picornavirus in Lambs with Severe Encephalomyelitis

Using metagenomic analysis, we identified a novel picornavirus in young preweaned lambs with neurologic signs associated with severe nonsuppurative encephalitis and sensory ganglionitis in 2016 and 2017 in the United Kingdom. In situ hybridization demonstrated intralesional neuronotropism of this virus, which was also detected in archived samples of similarly affected lambs (1998–2014).

Genetic diversity and evolution of the emerging picornavirus Senecavirus A

Senecavirus A (SVA) is an emerging picornavirus that causes vesicular disease (VD) in swine. The virus has been circulating in swine in the United Stated (USA) since at least 1988, however, since 2014 a marked increase in the number of SVA outbreaks has been observed in swine worldwide. The factors that led to the emergence of SVA remain unknown. Evolutionary changes that accumulated in the SVA genome over the years may have contributed to the recent increase in disease incidence. Here we compared full-genome sequences of historical SVA strains (identified before 2010) from the USA and global contemporary SVA strains (identified after 2011). The results from the genetic analysis revealed 6.32 % genetic divergence between historical and contemporary SVA isolates. Selection pressure analysis revealed that the SVA polyprotein is undergoing selection, with four amino acid (aa) residues located in the VP1 (aa 735), 2A (aa 941), 3C (aa 1547) and 3D (aa 1850) coding regions being under positive/diversifying selection. Several aa substitutions were observed in the structural proteins (VP1, VP2 and VP3) of contemporary SVA isolates when compared to historical SVA strains. Some of these aa substitutions led to changes in the surface electrostatic potential of the structural proteins. This work provides important insights into the molecular evolution and epidemiology of SVA.

Molecular-based investigation and genetic characterization of porcine stool-associated RNA virus (posavirus) lineages 1 to 3 in pigs in South Korea from 2017 to 2019

Recent results on the detection and genetic characterization of stool-associated RNA viruses from different species have increased the knowledge about the extreme genetic diversity of picornaviruses. This study aimed to investigate the presence of unclassified porcine stool-associated RNA viruses (posaviruses) in South Korea and to elucidate the molecular evolution of the viruses. By RT-PCR, posaviruses 1 and 3 were exclusively found in fecal samples and consistently detected in three consecutive years in six of eight provinces, with 148/697 (21.2%) and 33/84 (39.3%) positive samples and farms, respectively. Every age group but the older age groups (finisher, sow) had significantly higher positive rates of posavirus 1 than posavirus 3. An analysis of the RNA-dependent RNA polymerase sequences by likelihood mapping and maximum-likelihood-based phylogenetic analysis revealed that stool-associated RNA viruses formed four supergroups that were well separated from all recognized families of the order Picornavirales. Five genomes of Korean posaviruses generated in this study were phylogenetically grouped with posavirus 1 and posavirus 3 and were predicted to have the typical genome organization of picornaviruses.

Equine Rhinitis A Virus Infection in Thoroughbred Racehorses-A Putative Role in Poor Performance?

The aim of this study was to identify respiratory viruses circulating amongst elite racehorses in a training yard by serological testing of serial samples and to determine their impact on health status and ability to race. A six-month longitudinal study was conducted in 30 Thoroughbred racehorses (21 two-year-olds, five three-year-olds and four four-year-olds) during the Flat racing season. Sera were tested for the presence of antibodies against equine herpesvirus 1 and 4 (EHV-1 and EHV-4) and equine rhinitis viruses A and B (ERAV and ERBV) by complement fixation (CF) and equine arteritis virus (EAV) by ELISA. Antibodies against equine influenza (EI) were measured by haemagglutination inhibition (HI). Only ERAV was circulating in the yard throughout the six-month study period. Seroconversion to ERAV frequently correlated with clinical respiratory disease and was significantly associated with subsequent failure to race (p = 0.0009). Over 55% of the two-year-olds in the study seroconverted to ERAV in May and June. In contrast, only one seroconversion to ERAV was observed in the older horses. They remained free of any signs of respiratory disease and raced successfully throughout the study period. The importance of ERAV as a contributory factor in the interruption of training programmes for young horses may be underestimated.

Vesicular disease in pigs inoculated with a recent Canadian isolate of Senecavirus A

The objective of this study was to investigate whether a virulent Canadian isolate of Senecavirus A (SVA) causes idiopathic vesicular disease (IVD) in pigs. Senecavirus A, which was first isolated in the United States in 2002 as Seneca Valley Virus, was linked to cases of porcine idiopathic vesicular disease in Canada in 2007 and in the United States in 2010. Since 2014, SVA outbreaks in Brazil, the US, Canada, China, Thailand, and Colombia point to an expanding global distribution and the need to study the pathogenicity of the virus. Unlike the prototype virus, recent US isolates of SVA have been shown to cause vesicular disease in pigs. We report vesicular disease in pigs following experimental inoculation with a 2016 Canadian isolate of SVA. All inoculated pigs developed vesicular lesions regardless of route of inoculation. Virus was detected in blood and oral fluids as well as on oral and fecal swabs. In addition, all pigs seroconverted to SVA by 6 days post-inoculation (DPI). This study confirms that recent Canadian isolates of SVA cause vesicular disease in pigs and highlights the importance of monitoring SVA for increased virulence.

Feline upper respiratory tract infection and disease in Australia

OBJECTIVES

The aim of this study was to conduct a comprehensive assessment of feline infectious upper respiratory tract infection (URTI) and disease (URTD) in Australian cats.

METHODS

Laboratory data demonstrating URTI from feline URTD multiplex PCR panel (feline herpesvirus 1 [FHV-1], feline calicivirus [FCV], Bordetella bronchiseptica, Chlamydophila felis, Mycoplasma felis and H1N1 influenza) submissions in Australia (2013-2015) were obtained. For comparison, reports of feline URTD during the same time period were sourced from a voluntary companion animal disease surveillance system.

RESULTS

A total of 3126 samples were submitted for testing; 1533 (49%) were positive. Of these, the most commonly detected agents were M felis (21.5%) and FCV (16.0%) alone, followed by FCV and M felis (13.4%) together as a respiratory infection complex, then FHV-1 (7.0%) alone. During the study period, there were 262 reports of 320 clinical feline URTD cases. Most cases (69%) were reported from New South Wales, <1 year of age (41%) and equally distributed between the sexes. Infection was more common in entire cats (69%) and most cases (55%) involved domestic shorthair cats. Of the 90 reports that had a known vaccination status, 63 had a vaccination history, 40 of which were recently vaccinated. Most (72%) feline URTD cases recovered from clinical disease. Both feline URTI and URTD were more common during winter months.

CONCLUSIONS AND RELEVANCE

Feline URTI and URTD cause substantial impact in Australia, being most commonly associated with M felis and FCV infection. This information can be used by veterinarians to educate clients about prevention and management of this important infectious disease of cats.

Bluegill Picornavirus isolated from a mortality event involving Bluegill (Lepomis macrochirus) in the upper Mississippi River

A mortality event involving an estimated 1,000 adult bluegills (Lepomis macrochirus) was observed in an ice-covered backwater lake of the upper Mississippi River near Alma, Wisconsin, in December of 2017. Macroscopic signs of disease included abdominal distension due to fluid accumulation within the internal organs as well as external and internal haemorrhaging. Histological evaluation revealed chronic peritonitis with peritoneal adhesions in all fish examined. Kidney, spleen and ascites fluid samples were collected from diseased bluegills and examined for the presence of pathogens. Bluegill picornavirus (BGPV) was isolated using tissue cell culture methods utilizing a recently developed, uncharacterized bluegill fry cell line (BF-4), and the presence of this virus was confirmed through molecular identification. The current geographic range, known susceptible hosts as well as historical epizootics associated with BPGV is discussed. The ability of BGPV to cause significant mortality in wild fish further emphasizes the importance of monitoring both wild and hatchery populations for this pathogen.

Pathogenicity of two Chinese Seneca Valley virus (SVV) strains in pigs

Seneca Valley virus (SVV) has been identified as the causative agent of SVV-associated vesicular disease (SAVD). To investigate the pathogenicity of two newly isolated SVV strains (GD-S5/2018 and GD04/2017) in China, experimental infections of pigs were performed. In pig experiments, both SVV strains successfully infected all animals, evidenced by presence of virus shedding and robust protective antibody responses. SVV GD-S5/2018 infection resulted in characteristic clinical signs, and ulcerative lesions on the tongue and gums. However, SVV GD04/2017 did not cause any clinical symptoms except depression in pigs during the experiment. Taken together, these results demonstrate that SVV GD-S5/2018 is a virulent strain for pigs, whereas SVV GD04/2017 is nearly avirulent. The established animal models for SVV infection will be utilized to dissect the immunity and pathogenesis, and develop vaccines and antivirals.

Improved one-tube RT-PCR method for simultaneous detection and genotyping of duck hepatitis A virus subtypes 1 and 3

Background

The cocirculation of duck hepatitis A virus subtypes 1 (DHAV-1) and 3 (DHAV-3) in ducklings has resulted in significant economic losses. Ducklings with DHAV-1 or DHAV-3 infection show similar clinical signs and gross lesions; hence, it is important to identify the viral subtypes in infected ducklings as early as possible for better clinical management.

Methods and results

Based on multiple 5’ noncoding region (5’-NCR) sequences of DHAV-1 and DHAV-3 strain alignments, universal and type-specific primers were designed and synthesized. With three primers in one-tube reverse transcription-PCR (RT-PCR), reference DHAV-1 and DHAV-3 isolates ranging over 60 years and across many different countries were successfully amplified, indicating that the primer sequences were completely conserved. The sequence results and the sizes of amplicons from reference DHAV-1 and DHAV-3 isolates are completely correlated with their subtypes. Moreover, with this one-tube RT-PCR system, amplicon sizes from liver samples of reference DHAV-1- or DHAV-3-infected birds fit closely with their subtypes, which was determined by virus isolation and neutralization testing. No other duck-origin RNA viruses were detected. The sensitivity of viral RNA detection was 10 pg. With this system, 20% subtype 1, 45% subtype 3, and 9% coinfection of two subtypes were detected in 55 clinical samples.

Conclusions and significance

This novel approach could be used for rapidly typing DHAV-1 or DHAV-3 infection in routine clinical surveillance or epidemiological screening.

Molecular detection and genomic characteristics of bovine kobuvirus from dairy calves in China

In this study, 96 diarrheic and 77 non-diarrheic fecal samples from dairy calves were collected from 14 dairy farms in 4 provinces to investigate the molecular prevalence and genomic characteristics of Bovine Kobuvirus (BKoV) in China. The results showed that the BKoV positive rate for the diarrheic feces (35.42%) was significantly higher than that for the non-diarrheic feces (11.69%, p < 0.001). Interestingly, three potential novel VP1 lineages were identified from 15 complete VP1 sequences, and a unique triple nucleotide insertion which can result in an aa insertion, was first observed in the 11/12 VP0 fragments with 660 bp long in this study, compared with known BKoV VP0 sequences. Moreover, the first Chinese BKoV genome was successfully obtained from a diarrheic fecal sample, named CHZ/CHINA. The open reading frame (ORF) of the genome from strain CHZ/China shares 87.4%–88.3% nucleotide (nt) and 93.7%–96.4% amino acid (aa) identity, compared with the three known genomes of BKoV. Interestingly, phylogenetic tree based on aa sequences of these genomes showed that CHZ/CHINA was clustered into an independent branch, suggesting the strain may represent a novel BKoV strain. The findings contribute to better understanding the molecular characteristics and evolution of BKoV.

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Three potential novel VP1 lineages in BKoV.

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A unique VP0 sequence type in BKoV.

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The first BKoV genome from China which may represent a novel BKoV strain.

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Contributing to better understanding the molecular characteristics of BKoV.

The role of Virus "X" (Tortoise Picornavirus) in kidney disease and shell weakness syndrome in European tortoise species determined by experimental infection

Tortoise Picornavirus (ToPV) commonly known as Virus "X" was recently discovered in juvenile European tortoises suffering from soft carapace and plastron as well as kidney disease. Therefore, this virus was a potential candidate to be a causative agent for these disease patterns. Spur thighed tortoises (Testudo graeca) seemed to be more susceptible to establish clinical symptoms than other European species like T. hermanni. Thus this trial investigated the role of ToPV in the described syndrome. Two groups of juvenile European tortoises (T. graeca and T.hermanni) each of 10 animals, were cloacally, oronasally and intracoelomically inoculated with an infectious dose (~ 2000 TICD) of a ToPV strain isolated from a diseased T. graeca. A control group of two animals of each species received non-infected cell culture supernatant. The tortoises were examined daily and pharyngeal and cloacal swabs for detection of ToPV-RNA by RT-PCR were taken from each animal every six days for a period of 6 months. At the end of the study the remaining animals were euthanised and dissected. Bacteriological and parasitological tests were performed and organ samples of all tortoises were investigated by RT-PCR for the presence of ToPV and histopathology. Animals that were euthanised at the end of the experiment, were examined for presence of specific anti-ToPV antibodies. Several animals in both inoculated groups showed retarded growth and a light shell weakness, in comparison to the control animals. Three animals were euthanised during the trial, showing reduced weight gain, retarded growth, severe shell weakness and apathy, in parallel to clinical observations in naturally infected animals. In all inoculated animals of both species an intermittent virus shedding, starting from 18 days post inoculation (d.p.i.), till 164 d.p.i. was detected, while the control animals remained negative. The virus was successfully reisolated in terrapene heart cell culture in 16 of 20 inoculated animals of both species. Histopathology of most inoculated animals revealed a lack of bone remodeling and vacuolisation in kidney tubuli which supports the described pathogenesis of nephropathy and osteodystrophy. Anti- ToPV antibody titres ranged from 1:2 to >1:256 in 13 of 20 animals, whereas all control animals were seronegative. The study proofed the Henle Koch`s postulates of ToPV as causative agent for shell dystrophy and kidney disease in both testudo species. The proposed species specific sensitivity towards clinical disease was not observed.