Development and Large-Scale Testing of a Novel One-Step Triplex RT-qPCR Assay for Simultaneous Detection of "Neurotropic" Porcine Sapeloviruses, Teschoviruses (Picornaviridae) and Type 3 Porcine Astroviruses (Astroviridae) in Various Samples including Nasal Swabs.

Porcine sapeloviruses, teschoviruses of family Picornaviridae and type 3 porcine astroviruses of family Astroviridae are (re-)emerging enteric pathogens that could be associated with severe, disseminated infections in swine, affecting multiple organs including the central nervous system (CNS). Furthermore, small-scale pioneer studies indicate the presence of these viruses in porcine nasal samples to various extents. The laboratory diagnostics are predominantly based on the detection of the viral RNA from faecal and tissue samples using different nucleic-acid-based techniques such as RT-qPCR. In this study, a novel highly sensitive one-step triplex RT-qPCR assay was introduced which can detect all known types of neurotropic sapelo-, tescho- and type 3 astroviruses in multiple types of samples of swine. The assay was evaluated using in vitro synthesized RNA standards and a total of 142 archived RNA samples including known sapelo-, tescho- and type 3 astrovirus positive and negative CNS, enteric and nasal specimens. The results of a large-scale epidemiological investigation of these viruses on n = 473 nasal swab samples from n = 28 industrial-type swine farms in Hungary indicate that all three neurotropic viruses, especially type 3 astroviruses, are widespread and endemically present on most of the investigated farms.

[Hind limb paralysis in fattening pigs due to a new strain of porcine Teschovirus A11]. / Hinterhandlähmungen bei Mastschweinen im Zusammenhang mit einem neuen Stamm des porzinen Teschovirus A11.

In a fattening farm in southern Germany, paralysis of the hind limbs was observed in 2 age groups (50 kg as well as 60 kg) during a 4 week period. Despite a low morbidity of 3.3 % the majority of the affected animals needed to be euthanized in consequence to the progression of their hind limb paralysis. During pathomorphological examinations of 2 affected fattening pigs severe lymphohistiocytic meningoencephalomyelitis and vasculitis were detected. Immunhistochemistry revealed the presence of Porcine Teschovirus antigen in all parts of the central nervous system as well as in several cell types (neurons, glia cells, endothelial cells, mononuclear cells). Porcine Teschovirus was detected by PCR in spinal cord samples. The subsequently performed phylogenetic analysis PCR revealed a close relation (88 % full genome sequence) to porcine Teschovirus A11 strain "Dresden". Other swine relevant pathogens were excluded by PCR, bacteriologic examination and sequencing. Following a period of 4 weeks no additional cases of hind limb paralysis were observed in the fattening farm.

Analysis of SARS-CoV-2 infection dynamic in vivo using reporter-expressing viruses.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the current COVID-19 pandemic, is one of the biggest threats to public health. However, the dynamic of SARS-CoV-2 infection remains poorly understood. Replication-competent recombinant viruses expressing reporter genes provide valuable tools to investigate viral infection. Low levels of reporter gene expressed from previous reporter-expressing recombinant (r)SARS-CoV-2 in the locus of the open reading frame (ORF)7a protein have jeopardized their use to monitor the dynamic of SARS-CoV-2 infection in vitro or in vivo. Here, we report an alternative strategy where reporter genes were placed upstream of the highly expressed viral nucleocapsid (N) gene followed by a porcine tescherovirus (PTV-1) 2A proteolytic cleavage site. The higher levels of reporter expression using this strategy resulted in efficient visualization of rSARS-CoV-2 in infected cultured cells and excised lungs or whole organism of infected K18 human angiotensin converting enzyme 2 (hACE2) transgenic mice. Importantly, real-time viral infection was readily tracked using a noninvasive in vivo imaging system and allowed us to rapidly identify antibodies which are able to neutralize SARS-CoV-2 infection in vivo. Notably, these reporter-expressing rSARS-CoV-2, in which a viral gene was not deleted, not only retained wild-type (WT) virus-like pathogenicity in vivo but also exhibited high stability in vitro and in vivo, supporting their use to investigate viral infection, dissemination, pathogenesis, and therapeutic interventions for the treatment of SARS-CoV-2 in vivo.

Porcine teschovirus, sapelovirus, and enterovirus in Swiss pigs: multiplex RT-PCR investigation of viral frequencies and disease association.

Porcine teschovirus (PTV), sapelovirus (PSV-A), and enterovirus (EV-G) are enteric viruses that can infect pigs and wild boars worldwide. The viruses have been associated with several diseases, primarily gastrointestinal, neurologic, reproductive, and respiratory disorders, but also with subclinical infections. However, for most serotypes, proof of a causal relationship between viral infection and clinical signs is still lacking. In Switzerland, there has been limited investigation of the occurrence of the 3 viruses. We used a modified multiplex reverse-transcription PCR protocol to study the distribution of the viruses in Swiss pigs by testing 363 fecal, brain, and placental or abortion samples from 282 healthy and diseased animals. We did not detect the 3 viruses in 94 placental or abortion samples or in 31 brain samples from healthy pigs. In brain tissue of 81 diseased pigs, we detected 5 PSV-A and 4 EV-G positive samples. In contrast, all 3 viruses were detected at high frequencies in fecal samples of both healthy and diseased pigs. In healthy animals, PTV was detected in 47%, PSV-A in 51%, and EV-G in 70% of the 76 samples; in diseased animals, frequencies in the 81 samples were 54%, 64%, and 68%, respectively. The viruses were detected more frequently in fecal samples from weaned and fattening pigs compared to suckling piglets and sows. Co-detections of all 3 viruses were the most common finding. Based on clinical and pathology data, statistical analysis yielded no evidence for an association of virus detection and disease. Further research is required to determine if pathogenicity is linked to specific serotypes of these viruses.

Swine polioencephalomyelitis in Brazil: identification of Teschovirus A, Sapelovirus A, and Enterovirus G in a farm from Southern Brazil.

Porcine encephalomyelitis can be associated with many etiologies, including viral agents, such as Porcine teschovirus (PTV), Porcine sapelovirus (PSV), and Porcine astrovirus (PoAstV). In this study, we investigated the presence of these viruses in a neurological disease outbreak in a swine farm in Southern Brazil. The piglet production farm unity had 1200 weaning piglets, and 40 piglets with neurological signs such as motor incoordination, paresis, and paralysis of hind limbs, with an evolution time of approximately 4 days. Among these, 10 piglets were submitted to postmortem examination. Gross lesions were restricted to a mild enlargement of the nerve roots and ganglia of spinal cord segments. The microscopic lesions were characterized by nonsuppurative encephalomyelitis and ganglioneuritis with evident neuronal degeneration and necrosis. Samples of the central nervous system (CNS), cerebrospinal fluid, and feces were collected and submitted to molecular analysis. PTV was identified in all samples of the CNS, while eight of the piglets were also positive for PSV, and seven were positive for Porcine enterovirus (EV-G). PoAstV was identified in a pool of feces of healthy animals used as controls. This study demonstrates the occurrence of encephalomyelitis associated with PTV on a swine farm in Southern Brazil, as well as the presence of other viruses such as PSV, EV-G, and PoAstV in the swineherd. Sequences of the fragments that were previously amplified by PCR showed a high similarity to PTV 6. Herein, we describe the first case report of severe swine polioencephalomyelitis associated with PTV in South America.

Isolation and genetic characteristics of a neurotropic teschovirus variant belonging to genotype 1 in northeast China.

Porcine teschovirus (PTV) is a causative agent of reproductive disorders, encephalomyelitis, respiratory diseases, and diarrhea in swine, with a worldwide distribution. In this work, we identified PTV-associated nonsuppurative encephalitis as a potential cause of posterior paralysis in neonatal pigs in northeast China. Using indirect immunofluorescence assay, western blot, electron microscopy, and genome sequencing, we identified a neurotropic PTV strain, named CHN-NP1-2016, in the supernatants of pooled cerebrum and cerebellum samples from an affected piglet. Nucleotide sequence alignment revealed that the whole genome of CHN-NP1-2016 shared the highest sequence similarity (86.76% identity) with PTV 1 strain Talfan. A combination of phylogenetic and genetic divergence analysis was applied based on the deduced amino acid sequence of the P1 gene with a cutoff value of the genetic distance (0.102 ± 0.008) for defining PTV genotypes, and this showed that CHN-NP1-2016 is a variant of genotype 1. In total, 16 unique mutations and five mutant clusters were detected in the capsid proteins VP1 and VP2 of CHN-NP1-2016 when compared to other PTV1 isolates. Importantly, we detected three mutant clusters located in the exposed surface loops of the capsid protein, potentially indicating significant differences in major neutralization epitopes. Moreover, a potential recombination event in the P1 region of PTV CHN-NP1-2016 was detected. These findings provide valuable insights into the role of recombination in the evolution of teschoviruses. To our knowledge, this is the first case report of PTV-1-associated encephalitis in northeast China. Future investigations will narrow on the serology and pathogenicity of this novel isolate.

Catalase impairs Leishmania mexicana development and virulence.

Catalase is one of the most abundant enzymes on Earth. It decomposes hydrogen peroxide, thus protecting cells from dangerous reactive oxygen species. The catalase-encoding gene is conspicuously absent from the genome of most representatives of the family Trypanosomatidae. Here, we expressed this protein from the Leishmania mexicana Β-TUBULIN locus using a novel bicistronic expression system, which relies on the 2A peptide of Teschovirus A. We demonstrated that catalase-expressing parasites are severely compromised in their ability to develop in insects, to be transmitted and to infect mice, and to cause clinical manifestation in their mammalian host. Taken together, our data support the hypothesis that the presence of catalase is not compatible with the dixenous life cycle of Leishmania, resulting in loss of this gene from the genome during the evolution of these parasites.

Expression of Separate Heterologous Proteins from the Rotavirus NSP3 Genome Segment Using a Translational 2A Stop-Restart Element.

The segmented 18.5-kbp dsRNA genome of rotavirus expresses 6 structural and 6 nonstructural proteins. We investigated the possibility of using the recently developed plasmid-based rotavirus reverse genetics (RG) system to generate recombinant viruses that express a separate heterologous protein in addition to the 12 viral proteins. To address this, we replaced the NSP3 open reading frame (ORF) of the segment 7 (pT7/NSP3) transcription vector used in the RG system with an ORF encoding NSP3 fused to a fluorescent reporter protein (i.e., UnaG, mRuby, mKate, or TagBFP). Inserted at the fusion junction was a teschovirus translational 2A stop-restart element designed to direct the separate expression of NSP3 and the fluorescent protein. Recombinant rotaviruses made with the modified pT7/NSP3 vectors were well growing and generally genetically stable, and they expressed NSP3 and a separate fluorescent protein detectable by live cell imaging. NSP3 made by the recombinant viruses was functional, inducing nuclear accumulation of cellular poly(A)-binding protein. Further modification of the NSP3 ORF showed that it was possible to generate recombinant viruses encoding 2 heterologous proteins (mRuby and UnaG) in addition to NSP3. Our results demonstrate that, through modification of segment 7, the rotavirus genome can be increased in size to at least 19.8 kbp and can be used to produce recombinant rotaviruses expressing a full complement of viral proteins and multiple heterologous proteins. The generation of recombinant rotaviruses expressing fluorescent proteins will be valuable for the study of rotavirus replication and pathogenesis by live cell imagining and suggest that rotaviruses will prove useful as expression vectors.IMPORTANCE Rotaviruses are a major cause of severe gastroenteritis in infants and young children. Recently, a highly efficient reverse genetics system was developed that allows genetic manipulation of the rotavirus segmented double-stranded RNA genome. Using the reverse genetics system, we show that it is possible to modify one of the rotavirus genome segments (segment 7) such that virus gains the capacity to express a separate heterologous protein in addition to the full complement of viral proteins. Through this approach, we have generated wild-type-like rotaviruses that express various fluorescent reporter proteins, including UnaG (green), mRuby (far red), mKate (red), and TagBFP (blue). Such strains will be of value in probing rotavirus biology and pathogenesis by live cell imagining techniques. Notably, our work indicates that the rotavirus genome is remarkably flexible and able to accommodate significant amounts of heterologous RNA sequence, raising the possibility of using the virus as a vaccine expression vector.

Detection and molecular characterization of porcine enterovirus G15 and teschovirus from India.

Porcine enterovirus G (EV-G) and teschovirus (PTV) generally cause asymptomatic infections. Although both viruses have been reported from various countries, they are rarely detected from India. To detect these viruses in Western India, fecal samples (n = 26) of diarrheic piglets aged below three months from private pig farms near Pune (Maharashtra) were collected. The samples were screened by reverse transcription-polymerase chain reaction using conserved enterovirus specific primers from 5' untranslated region. For genetic characterization of detected EV-G strain, nearly complete genome, and for PTV, partial VP1 gene were sequenced. EV-G strain showed the highest identity in a VP1 gene at nucleotide (78.61%) and amino acid (88.65%) level with EV-G15, prototype strain. However, its complete genome was homologous with the nucleotide (78.38% identity) and amino acid (91.24% identity) level to Ishi-Ka2 strain (LC316832), unassigned EV-G genotype detected from Japan. The nearly complete genome of EV-G15 consisted of 7398 nucleotides excluding the poly(A) tail and has an open reading frame that encodes a 2170 amino acid polyprotein. Genetic analysis of the partial VP1 gene of teschovirus identified porcine teschovirus 4 (PTV-4) and putative PTV-17 genotype. To the best of our knowledge, this is the first report on nearly full genome characterization of EV-G15, and detection of PTV-4 and putative PTV-17 genotypes from India. Further, detection and characterization of porcine enteroviruses are needed for a comprehensive understanding of their genetic diversity and their association with symptomatic infections from other geographical regions of India.

Production of an antibody Fab fragment using 2A peptide in insect cells.

Antibody Fab fragments consist of heavy chain (Hc) and light chain (Lc) polypeptides assembled with a disulphide bond. The production of a recombinant Fab fragment requires the simultaneous expression of two genes encoding both an Hc and an Lc in the same host cell. In the present study, we investigated the production of Fab fragments in lepidopteran insect cells using a bicistronic plasmid vector carrying the Hc and Lc genes linked with a 2A self-cleaving peptide sequence from the porcine teschovirus-1. We also examined the arrangement of a GSG spacer sequence and a furin cleavage site sequence with the 2A sequence. Western blot analysis and enzyme-linked immunosorbent assay (ELISA) of culture supernatants showed that Trichoplusia ni BTI-TN-5B1-4 (High Five) cells transfected with a plasmid in which the Hc and Lc genes were joined by the 2A sequence successfully secreted Fab fragments with antigen-binding activity after self-cleavage of the 2A peptide. The GSG linker enhanced 2A cleavage efficiency, and the furin recognition site was useful for removal of 2A residues from the Hc. Transfection with a single plasmid that contained sequences for GSG, the furin cleavage site, GSG, and the 2A peptide between the Hc and Lc genes exhibited a higher productivity than co-transfection with a set of plasmids separately carrying the Hc or Lc gene. These results demonstrate that bicistronic expression with the appropriate combination of a furin recognition site, GSG linkers, and a 2A peptide may be an effective way to efficiently produce recombinant antibody molecules in insect cells.

Identification of novel genotypes belonging to the species Teschovirus A from indigenous pigs in western Jiangxi, China.

Teschovirus A is currently the sole species in the genus Teschovirus, whose members are divided into 13 subtypes: porcine teschovirus (PTV) 1-13. However, recent discoveries of novel PTV genotypes have suggested that a new species, "Teschovirus B", should be established. Here, we have identified six of the 19 known genotypes and two novel genotypes (PTV 17-18), revealing the high genetic diversity of the PTV subpopulation in indigenous pigs of western Jiangxi, China. Moreover, we determined the nearly complete genome sequences of PTV 17-SG9 and PTV 18-SG10. Together with PTV 1-13, these novel genotypes were confirmed to be members of the species Teschovirus A based on phylogenetic and genetic divergence analysis. Consequently, the species Teschovirus A now includes at least 15 PTV genotypes.

Two novel porcine teschovirus strains as the causative agents of encephalomyelitis in the Netherlands.

BACKGROUND: Porcine teschovirus (PTV) circulates among wild and domesticated pig populations without causing clinical disease, however neuroinvasive strains have caused high morbidity and mortality in the past. In recent years, several reports appeared with viral agents as a cause for neurologic signs in weanling and growing pigs among which PTV and new strains of PTV were described. CASE PRESENTATION: On two unrelated pig farms in the Netherlands the weanling pig population showed a staggering gate, which developed progressively to paresis or paralysis of the hind legs with a morbidity up to 5%. After necropsy we diagnosed a non-suppurative encephalomyelitis on both farms, which was most consistent with a viral infection. PTV was detected within the central nervous system by qPCR. From both farms PTV full-length genomes were sequenced, which clustered closely with PTV-3 (98%) or PTV-11 (85%). Other common swine viruses were excluded by qPCR and sequencing of the virus. CONCLUSION: Our results show that new neuroinvasive PTV strains still emerge in pigs in the Netherlands. Further research is needed to investigate the impact of PTV and other viral agents causing encephalomyelitis within wild and domestic pig populations supported by the awareness of veterinarians.

Novel species of Teschovirus B comprises at least three distinct evolutionary genotypes.

Conventionally, Porcine teschovirus (PTV) consists of 13 genotypes (PTV 1-13, which belong to Teschovirus A); however, several novel members including PTV 14-22 have been discovered recently. PTV 21 was identified as a novel Teschovirus species named Teschovirus B. In this study, almost all 22 reported PTV genotypes except PTV 6, 7, 12 and 20 were identified in the pig populations of western Jiangxi, China, which reflects the high genotype diversity. Moreover, to the best of our knowledge, the nearly complete genome of PTV 22-JiangX1 was first sequenced in the present study. The homology comparison of the polyprotein genes showed that PTV 22-JiangX1 shared a relatively high nucleotide and deduced amino acid sequence identities ranging from 78.3% to 82.0% and 84.6% to 89.3%, respectively, with PTV 19 and 21. Additionally, the PTV strain of JiangX1 represents genotype 22 with the PTV 19, and 21 strains proved to be members of Teschovirus B based on the phylogenetic and evolutionary divergence analyses. Finally, we determined that the novel Teschovirus B species comprises at least three PTV genotypes.

Identification and genotypic characterization of porcine teschovirus from selected pig populations in India.

Porcine teschovirus (PTV) previously classified as porcine enteroviruses in the family Picornaviridae are associated with a wide range of illnesses in swine ranging from asymptomatic infection to acute fatal encephalomyelitis, diarrhea, and pneumonia. This study was planned to investigate whether porcine teschovirus is prevalent among pigs in India and to characterize the PTV identified in the study population. The study conducted in certain farms of North India revealed that 13 of 190 (6.84%) fecal samples were PTV positive by RT-PCR. Three viruses were successfully isolated from fecal samples using IB-RS-2 cell lines which were confirmed by RT-PCR and sequencing. Molecular characterization based on the VP1 region of the viral genome identified the isolated viruses as serotype 5 and serotype 8 of PTV. A new variant of teschovirus was also identified which showed significant nucleotide diversity from the known serotypes of the teschoviruses. This is the first report of isolation, identification, and characterization of porcine teschoviruses in India.

Teschovirus and other swine and human enteric viruses in Brazilian watersheds impacted by swine husbandry.

Several emerging viral agents related to gastroenteritis are distributed in human and animal populations and may contaminate the environment due to anthropic activities. The objective of this study was to analyze the seasonal contamination by enteric virus and coliforms in water from streams in the Vale do Taquari, draining a large number of pig farms. Microbiological contamination was evidenced by the detection of total and thermotolerant coliforms, reaching their peak in December. Hepatitis E virus (HEV), Enterovirus-G (EV-G) genome, and Sapelovirus-A (SV-A) genome were not detected. On the other hand, Rotavirus (RV) was detected in 3% (1/32) of the samples, whereas Teschovirus-A (PTV) was detected in 6% (2/32). This is the first detection of PTV in environmental samples in Brazil, pointing that the virus is being shedded from swine herds to watersheds. Human mastadenovirus (HAdV) was the most frequent detected viral agent in 9.3% (3/32) with values of 2.54 × 105, 7.13 × 104, and 3.09 × 105 genome copies/liter (gc/L). The circulation of coliforms and viral pathogens is noticeable due to anthropic activities and to the management of animal waste from the pig farming. In this way, enteric viruses can assist in monitoring the quality of watersheds and in tracking sources of contamination.

Real-Time Temporal Dynamics of Bicistronic Expression Mediated by Internal Ribosome Entry Site and 2A Cleaving Sequence.

Multicistronic elements, such as the internal ribosome entry site (IRES) and 2A-like cleavage sequence, serve crucial roles in the eukaryotic ectopic expression of exogenous genes. For utilization of multicistronic elements, the cleavage efficiency and order of elements in multicistronic vectors have been investigated; however, the dynamics of multicistronic element-mediated expression remains unclear. Here, we investigated the dynamics of encephalomyocarditis virus (EMCV) IRES- and porcine teschovirus-1 2A (p2A)-mediated expression. By utilizing real-time fluorescent imaging at a minute-level resolution, we monitored the expression of fluorescent reporters bridged by either EMCV IRES or p2A in two independent cultured cell lines, HEK293 and Neuro2a. We observed significant correlations for the two fluorescent reporters in both multicistronic elements, with a higher correlation coefficient for p2A in HEK293 but similar coefficients for IRES-mediated expression and p2A-mediated expression in Neuro2a. We further analyzed the causal relationship of multicistronic elements by convergent cross mapping (CCM). CCM revealed that in all four conditions examined, the expression of the preceding gene causally affected the dynamics of the subsequent gene. As with the cross correlation, the predictive skill of p2A was higher than that of IRES in HEK293, while the predictive skills of the two multicistronic elements were indistinguishable in Neuro2a. To summarize, we report a significant temporal correlation in both EMCV IRES- and p2A-mediated expression based on the simple bicistronic vector and real-time fluorescent monitoring. The current system also provides a valuable platform to examine the dynamic aspects of expression mediated by diverse multicistronic elements under various physiological conditions.

Longitudinal survey of Teschovirus A, Sapelovirus A, and Enterovirus G fecal excretion in suckling and weaned pigs.

Fecal samples from 27 pigs were longitudinally analyzed for Teschovirus A (TV-A), Sapelovirus A (SV-A), and Enterovirus G (EV-G) RNA presence. Suckling piglet fecal samples were negative for the three enteric picornaviruses. However, these picornaviruses were detected in 22/27 weaned pig fecal samples. This study provides new data on TV-A, SV-A, and EV-G infection dynamics.

Metagenomic identification and sequence analysis of a Teschovirus A-related virus in porcine feces in Japan, 2014-2016.

Porcine Teschoviruses (PTVs) are associated with polioencephalomyelitis and various diseases, including reproductive and gastrointestinal disorders, of pigs and wild boars, and are also detected in the feces of healthy pigs. The genus Teschovirus contains a single species Teschovirus A that currently includes 13 serotypes. In the present study, we identified novel PTVs that are distantly related to Teschovirus A and were found in fecal samples of pigs with or without diarrhea in Japan. Phylogenetic analysis of amino acid (aa) sequences of the complete coding region revealed that these newly identified viruses did not cluster with any strains of PTVs or other strains within the picornavirus supergroup 1, suggesting that the viruses may not belong to Teschovirus A or any genus of the family Picornaviridae. These novel PTVs share a type IV internal ribosomal entry site and conserved characteristic motifs in the coding region, yet exhibit 62.2-79.0%, 86.6-92.8%, 77.1-81.0%, and 84.3-86.7% aa identities to PTV strains in P1, 2C, 3C, and 3D regions, respectively. In contrast, PTV 1-13 strains of the Teschovirus A share 76.5-92.1%, 88.1-99.7%, 93.2-100%, and 95.8-100% aa identities in the P1, 2C, 3C, and 3D, respectively, within the species. These data imply that the newly identified viruses belong to teschoviruses, and may represent a novel species in the genus Teschovirus.

Prevalence of Porcine teschovirus genotypes in Hunan, China: identification of novel viral species and genotypes.

Porcine teschovirus (PTV) comprises at least 13 genotypes (PTV 1-13). Here, the genotypes of field strains prevalent among pig populations in Hunan Province, China, were identified. Multiple PTV genotypes, including all genotypes except PTV 7 and 8, were found co-circulating in the pig populations, reflecting a high genetic diversity. Moreover, we identified nine novel PTV genotypes, provisionally designated as PTV 14-22. PTV 21-HuN41 and PTV 21-HuN42 were successfully isolated, and their nearly complete genomes were sequenced. Homology comparison of the polyprotein genes of PTV 21-HuN41-42 to those of other known PTVs revealed low identities, ranging from 70.1 to 71.9 % (nucleotide identity) and 75.4 to 77.6 % (amino acid identity). Moreover, PTV 21-HuN41-42 were identified as a novel teschovirus species (tentatively Teschovirus B), based on the analyses of phylogenetics and evolutionary divergence. The findings of this study are expected to greatly enrich our knowledge of PTV genotypes.

Molecular characterization of a porcine teschovirus HuN-1 isolate proliferating in PK-15 cell.

BACKGROUND: Porcine teschoviruses (PTVs) are small non-enveloped viruses with single-stranded, positive sense genomic RNA, belonging to the family Picornaviridae. Natural infections of teschoviruses are limited to pigs. RESULTS: In this study, a PTV HuN-1 was found that it could be proliferated in PK-15 cell, and it came from the pig fecal samples from Hunan province, in central China. The complete genome of the HuN-1 was amplified by RT-PCR and sequenced. The complete genome of HuN-1 isolate is 7098 nt, which shares the highest sequence identity (85.9%) with the PTV 8 strain of Jilin/2003/2 and Fuyu/2009/2. The HuN-1 isolate contains only one ORF (from 320 to 7039 nt) coding a 2240 amino acid polyprotein. Aligned sequences show that more mutations occurred in the structural region than in the nonstructural region. Phylogenetic analysis showed that HuN-1 isolate did not clustered with the hitherto reported strains, according to P1 sequences, forming a subgroup in the PTV cluster. CONCLUSION: In this study, complete genome of PTV HuN-1 was cloned and sequenced. Detection and characterization of further PTV strains from different geographic areas are important to understand the worldwide distribution and heterogeneity (serotype) of PTVs and their association with symptomatic infections in pigs.