Pathology and Molecular Characterization of Porcine Sapelovirus in Indian Pigs

Background: The porcine sapelovirus (PSV) is a small, non-enveloped, single-stranded, positive-sense, RNA virus of the family Picornaviridae. The PSV infections in pigs have been found associated with diarrhoea, polioencephalomyelitis, pneumonia and reproductive disorders with a high morbidity rate. Despite of its economical importance very few studies are available on the pathology of PSV. The present study was conducted with the aim to investigate the PSV infection and associated pathology in Indian pigs. Methods: Tissue samples along with intestinal content were collected from a total of 78 necropsied cases for histopathological examination and molecular investigation during April 2019 to August 2020. The amplification of 5' UTR region of PSV was carried out via RT-PCR and confirmed by sequencing. The Genetic characterization of Indian isolate of the PSV was done on the basis of viral 5' UTR gene. Result: A total of eight out of 78 cases were found positive for the PSV. Catarrhal and haemorrhagic enteritis, thickening and clouding of brain meninges along with congestion of brain and pneumonia was observed as common gross lesions. Microscopic lesions included perivascular cuffing, focal gliosis, neuronophagia, congestion of meningeal and cerebral vessels, interstitial pneumonia, inflammatory changes in the intestinal mucosa and sloughing of villi. The genetic characterization revealed maximum identity of 96.89% with PSV-1 strain PSV-46-V (LC508233) and PSV-1 strain PSV-26-B (LC508232) of Zambia. This study reported the pathological and molecular investigation of PSV from Indian pigs. Further explorative surveillance along with experimental studies in suitable animal model and cell lines are highly warranted for better understanding of PSV pathology in Indian pigs.

Characterization of porcine sapelovirus prevalent in western Jiangxi, China

Background Porcine sapelovirus (PSV) infection can lead severe polioencephalomyelitis with high morbidity and mortality, which result in significant economic losses. Infection with the PSV is believed to be common yet limited information is available on the prevalence and molecular characterization of PSV in China. Therefore, the objective of this study was to characterize the prevalence and genome of PSV strains identified in the western Jiangxi province of China. Results A high specificity and sensitivity SYBR Green I-based RT-PCR method for PSV detection was developed. Two hundred and ninety four fecal samples were collected from December 2018 to March 2019 in 4 farms. An overall PSV-positivity rate of 11.22% (33/294) was detected with the real-time RT-PCR method, and a high infection rate and viral load of PSV were found in nursery pigs. In total, complete VP1 gene sequences of 11 PSV strains (PSV-YCs) were obtained. Homology comparisons of the VP1 gene of the 11 PSV-YCs with previously reported PSVs revealed nucleotide sequence identities ranging from 63% to 96.8%, and deduced amino acid sequence identities from 61.4% to 99.7%. Phylogenetic analyses based on the VP1 gene exhibited 2 main clades corresponding to PSV-1 and PSV-2, and all PSV-YCs prevalent in western Jiangxi belonged to the traditional genotype (PSV-1). In addition, the pairwise distances of VP1 gene sequences between PSV-YCs ranged from 0.009 to 0.198, which indicating that substantial genetic diversity among the PSVs in western Jiangxi. Conclusions To the authors’ knowledge, this is the first description of PSV in the Jiangxi province pig herds in China, and it is crucial to understand the epidemiology of the viruses in China. The results also provide an important theoretical foundation for diagnosis and early warning of epidemic diseases caused by PSVs prevailing in this region.

Characterization of a Porcine Sapelovirus Strain Isolated in China

Background: Porcine sapelovirus (PSV) infections have been associated with a wide spectrum of symptoms ranging from asymptomatic infection to clinical signs including diarrhea, pneumonia, reproductive disorders, and polioencephalomyelitis. Although PSV is an important pathogen due to its wide distribution and high prevalence rate, researches on PSV have been relatively few so far.Methods: In this study, we isolated a PSV strain, SHCM2019, from swine faecal specimens from PK15 cells. To investigate the molecular characteristics and pathogenicity of the PSV strain, the genomic sequence of the SHCM2019 strain was analysed, and the clinical manifestations and pathological changes exhibited by inoculated neonatal piglets were observed. Results: Sequencing results showed that the full-length genome of the SHCM2019 strain was 7567 nucleotides in length excluding the 27-nucloetude poly(A) tail. Phylogenetic analyses demonstrated that the virus isolate belongs to PSV and was classified into the China cluster. RNA recombination analysis indicated that there may be a recombination breakpoint upstream of the 3D region in PSVs. Pathogenicity research demonstrated that the virus isolate could cause diarrhoea and pneumonia in piglets. Conclusion: This study presented the isolation of a recombinant PSV strain, SHCM2019 and demonstrated the isolate was pathogenic. Our results may provide a reference for future research investigating of the pathogenic mechanism and evolutionary characteristics of PSV.

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.

Detection and Characterization of Porcine Sapelovirus in Italian Pig Farms

Porcine sapelovirus (PSV) belongs to the genus Sapelovirus of the family Picornaviridae. PSV infects pigs asymptomatically, but it can also cause severe neurologic, enteric, and respiratory symptoms or reproductive failure. Sapelovirus infections have been reported worldwide in pigs. The objective of this study was to investigate the presence and the prevalence of PSV in Italian swine farms in animals of different ages to clarify the occurrence of the infection and the genetic characteristics of circulating strains. In the present study, 92 pools of fecal samples, collected from pigs across three farms, were analyzed by Reverse Transcriptase-polymerase Chain Reaction-PCR (RT-PCR). Fecal pools from young growers (63/64) were found positive for Sapelovirus in all farms while detection in sows (4/28) was observed in only one farm. Phylogenetic analyses of the 19 partial capsid protein nucleotide sequences (VP1) (6–7 each farm) enable the classification of the virus sequences into three distinct clades and highlighted the high heterogeneity within one farm. The whole genome sequence obtained from one strain showed the highest correlation with the Italian strain detected in 2015. The study adds novel information about the circulation and heterogeneity of PSV strains in Italy and considering the movement of pigs across Europe would also be informative for other countries.

Isolation and full-genome sequencing of porcine sapelovirus strain in piglets from Hainan province, China

Background: Porcine sapelovirus (PSV) is a species of the genus Sapelovirus within the family Picornaviridae, which associated with facute diarrhoea, respiratory distress, reproductive failure, and severe neurological disorders in swine. The first isolate strian of PSV was reported in Hainan province, China in 2019. Results: We report the isolation, genomic sequence of PSV isolated from pig diarrhea samples. The PSV strain was correctly identified by RT-PCR, IFA, WB assays, which appeared spherical with a diameter of approximately 25 nm by TEM. We named the strain PSV HaN01-CH2019, and its full genomes were 7,551 bp nucleotides in length. Phylogenetic analysis revealed that PSV HaN01-CH2019 and Chinese HuN01 strain are related in comparing with other reference strains. Conclusions: We successfully isolated the first PSV strain in Hainan province and prepared polyclonal antibodies. It is evident that PSV infection has occurred in Hainan province, and therefore, active molecular and serological investigation is important to swine population. Moreover, veterinarians must pay attention to this diarrhoea and reinforce biosecurity measures to prevent PSV spread.

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.

One-step triplex reverse-transcription PCR detection of porcine epidemic diarrhea virus, porcine sapelovirus, and porcine sapovirus

Swine diarrhea can be caused by multiple agents, including porcine epidemic diarrhea virus (PEDV), porcine sapelovirus (PSV), and porcine sapovirus (SaV). We designed a one-step triplex reverse-transcription PCR (RT-PCR) detection method including 3 pairs of primers that focused on the S1 gene of PEDV, a conserved gene of PSV, and the VP1 gene of SaV. The optimal concentrations of upstream and downstream primers in the triplex RT-PCR were 0.24 μM for PEDV, 0.15 μM for PSV, and 0.2 μM for SaV, and the optimal annealing temperature was 55.5°C. Triplex RT-PCR assessment of 402 piglet diarrhea samples was compared with conventional individual RT-PCR. Concordance rates in both tests for individual viruses were 100%, 97.6%, and 94.4% for PEDV, PSV, and SaV, respectively. PEDV, PSV, and SaV were detected in 57.2%, 10.4%, and 9.0% of the samples, respectively. The high sensitivity and specificity of this triplex RT-PCR–based detection method for PEDV, PSV, and SaV could allow rapid detection and analysis of mixed infections by these 3 viruses.