First isolation and genetic characteristics of porcine sapeloviruses in Hunan, China.

Outbreaks of diarrhea in piglets cause serious economic consequences in China. Diarrhetic fecal samples from 20 Hunan farm piglets were tested and found to be positive for porcine epidemic diarrhea virus (PEDV) by RT-PCR, although incubation with porcine kidney (PK-15) cells failed to produce infectious PEDV. Four porcine sapelovirus (PSV) strains (designated as PSV-HuNs) were isolated from four of the samples. Genomic sequence analysis revealed open reading frames encoding polyproteins of 2,331 (HuN1, 2 and 3) and 2,332 (HuN4) amino acids. Homology comparisons of the VP1 gene of the four Hunan strains with previously reported PSV strains revealed nucleotide sequence identities ranging from 74.2 to 98.6%, and deduced amino acid sequence identities from 79.5 to 98%. Phylogenetic analyses based on full-length and partial VP1 gene sequences showed that 3 of the PSV-HuN strains (HuN2, 3 and 4) clustered within a clade distinct from HuN1 as well as from all PSVs previously isolated in China, thereby showing that genetic diversity exists within Chinese PSVs. In addition, recombination analysis among PSVs indicates that a recombinant (HuN2 strain) exist in China.