Characterization of a novel porcine enterovirus in domestic pig in Hungary

Abstract

Porcine enteroviruses (PEVs) of genus Enterovirus are small, non-enveloped viruses with single-stranded, positive sense genomic RNA, belonging to the family Picornaviridae. The discovery of two distinct serotypes (PEV9 and 10) was first reported in 1979. Despite the sporadic detection and partial genome sequences of these viruses our knowledge about the prevalence and molecular epidemiology of PEV types in domestic pigs is very deficient. In this study, we identified a novel PEV from fecal samples of clinically healthy pigs ( Sus scrofa domestica) in Hungary by RT-PCR using human enterovirus generic primer pairs for 5′UTR region, with subsequent partial VP1 and complete genome sequencing and phylogenetic analysis. Among 45 fecal and blood sample pairs collected at the same farm from domestic pigs divided into three age groups (10 days, 4 weeks, and 3 months of age, N = 15 each group) six (40%) of the 15 fecal samples of 10-day-old pigs were enterovirus-positive. PEV was not detected in serum samples. Sequence- and phylogenetic analysis of the complete genome of swine/K23/2008/HUN (HQ702854) show relationship to PEV strains but it is separated from the PEV9 and 10, especially in structural regions. Swine/K23/2008/HUN has average of 77 and 75% amino acid identity in the P1 region, and only 61% in VP1 region to PEV9 and 10, respectively. The partial VP1 sequences of the Hungarian PEV strains show 99% nucleotide identity compared to each other. PEVs could be capable of at least local endemic spread among newborn piglets and cause no clinical symptoms or viraemia. Sequence data indicates that the Hungarian PEV strain belongs to a novel PEV. To clarify the taxonomic confusion related to PEV – as a consequence of recent extensive taxonomic changes among porcine enteric picornaviruses – we propose that PEV9 and PEV10 should be reclassified as PEV1 and PEV2. In this classification swine/K23/2008/HUN represents PEV3.