Abstract
BackgroundPorcine kobuvirus (PKoV) is a member of the Kobuvirus genus within the Picornaviridae family. PKoV is distributed worldwide with high prevalence in clinically healthy pigs and those with diarrhea.MethodsFecal and intestinal samples (n = 163) from pig farms in Sichuan Province, China were obtained to determine the presence of PKoV using reverse transcription polymerase chain reaction assays. Specific primers were used for the amplification of the gene encoding the PKoV VP1 protein sequence. Sequence and phylogenetic analyses were conducted to clarify evolutionary relationships with other PKoV strains.ResultsApproximately 53% (87/163) of pigs tested positive for PKoV. PKoV was widespread in asymptomatic pigs and those with diarrhea. A high prevalence of PKoV was observed in pigs younger than 4 weeks and in pigs with diarrhea. Phylogenetic analysis of 36 PKoV VP1 protein sequences showed that Sichuan PKoV strains formed four distinct clusters. Two pigs with diarrhea were found to be co-infected with multiple PKoV strains. Sequence and phylogenetic analyses revealed diversity within the same host and between different hosts. Significant recombination breakpoints were observed between the CHN/SC/31-A1 and CHN/SC/31-A3 strains in the VP1 region, which were isolated from the same sample.ConclusionPKoV was endemic in Sichuan Province regardless of whether pigs were healthy or suffering from diarrhea. Based on our statistical analyses, we suggest that PKoV was the likely causative agent of high-mortality diarrhea in China from 2010. For the first time, we provide evidence for the co-existence of multiple PKoV strains in one pig, and possible recombination events in the VP1 region. Our findings provide further insights into the molecular properties of PKoV, along with its epidemiology.
Highlights
Porcine kobuvirus (PKoV) is a member of the Kobuvirus genus within the Picornaviridae family
Statistical analysis showed that porcine kobuvirus infection strongly correlated with suckling pigs, which were younger than 4 weeks old (χ2 = 10.941, p = 9.4 × 10-4)
PKoV infection was significantly associated with diarrhea in pigs (χ2 = 17.126, p = 3.5 × 10-5) using Pearson’s chi-square test
Summary
Porcine kobuvirus (PKoV) is a member of the Kobuvirus genus within the Picornaviridae family. Members of the Picornaviridae are small, non-enveloped viruses with a linear single-stranded, positive-sense RNA genome. They are a highly diverse virus family, with a number of picornaviruses known to be important pathogens of humans and other animals [1,2,3]. PKoV was detected in a Hungary farm in early 2007 and the complete genome (strain swine/S-1-HUN/2007/Hungary) characterized [4] Since it was first identified, PKoV has been detected in China, Thailand, Spain, Japan, Korea, the United States, Brazil, the Netherlands, and recently in the Czech Republic [19,20,21,22,23,24,25,26]. In China, PKoV was detected in 38.8% (45/116) and 30.12% (97/322) of samples from Shanghai and Lulong County, respectively [30,31]
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