Porcine group A rotavirus (GARV) is considered to be an important animal pathogen due to their economic impact in the swine industry and its potential to cause heterologous infections in humans. This study examined 475 fecal samples from 143 farms located in 6 provinces across South Korea. RT-PCR and nested PCR utilizing primer pairs specific for the GARV VP6 gene detected GARV-positive reactions in 182 (38.3%) diarrheic fecal samples. A total of 98 porcine GARV strains isolated from the GARV-positive feces were analyzed for G and P genotyping. Based on the sequence and phylogenetic analyses, the most predominant combination of G and P genotypes was G5P[7], found in 63 GARV strains (64.3%). The other combinations of G and P genotypes were G8P[7] (16 strains [16.3%]), G9P[7] (7 strains [7.1%]), G9P[23] (2 strains [2.0%]), and G8P[1] (1 strain [1.0%]). The counterparts of G or P genotypes were not determined in three G5, five P[7], and one P[1] strains. Interestingly, phylogenetic analysis indicated that all Korean G9 strains were more closely related to lineage VI porcine and human viruses than to other lineages (I-V) of GARVs and to Korean human G9 strains (lineage III). These results show that porcine GARV infections are common in diarrheic piglets in South Korea. The infecting strains are genetically diverse, and include homologous (G5P[7]), heterologous (G8P[1]), and reassortant (G8P[7]), as well as emerging G9 GARV strains.

By sequence and phylogenetic analyses, the 11 genomic segments of two bovine rotaviruses isolated from clinically infected calves were proven to be derived from the swine-like P[7]G5 genotype. This finding reinforced the hypothesis that interspecies transmission of completely heterologous strains can occur in nature.Group A rotavirus (GARV), a member of the Reoviridae family, is a major cause of gastroenteritis in young children as well as in many animal species worldwide (3). The rotavirus genome is enclosed in three concentric layers and is composed of 11 segments of double-stranded RNA, which encode six structural proteins (VP1 to -4 and VP6 to -7) and five nonstructural proteins (NSP1 to -5) (3). This unique segmented nature of GARV genomes would enable reassortment between different viruses during coinfection and induce production of progeny viruses with novel or atypical phenotypes as noted above (3).GARVs have a wide host range, but individual strains appear to be restricted to single hosts (7). In humans, the most common G serotypes are G1, G2, G3, and G9 and two main P genotypes are P[4] and P[8] (12). In pigs, there are at least four major G serotypes (G3, G4, G5, and G11) and two dominant P genotypes (P[6] and P [7]) (13). In cattle, serotypes G6, G8, and G10, in combination with genotypes P[1], P [5], and/or P [11], are the serotypes most commonly found (1). However, there is now increasing evidence that the transmission of GARVs can occur from animal to human as well as from animal to animal either by direct transmission of the virus or by the contribution of one or several genes to reassortants (9, 10). However, there is little evidence for the existence of bovine GARVs bearing all genomic segments of porcine origin.The aim of this study was to characterize all 11 genomic segments of the two Korean bovine GARV strains. The results showed that both strains had swine-like genomic segments. These results contribute to a better understanding of interspecies transmission of heterologous GARVs.Two bovine GARV strains (K5 and K8) were isolated from diarrheic fecal samples of two calves from different farms during 2004 and 2005. These strains were propagated and plaque purified three times, using a plaque assay as described elsewhere (11). The viral genomic double-stranded RNA was extracted from the virus-infected TF-104 cells, characterized by reverse transcription-PCR, and sequenced using specific primer pairs (11). Each gene sequence of the two strains was compared with those of other known GARVs (see Table S1 in the supplemental material) by the use of DNA Basic module software (DNAsis MAX, Alameda, CA). Phylogenetic and sequence analyses based on the deduced amino acid alignments were performed as described previously (11).We compared the full-length (354 amino acids) VP7 protein sequence of the two Korean GARV strains with those of the GARV strains representative of all 16 G genotypes (4). Both strains showed the highest (92% to 100%) sequence identity to the porcine G5 GARV strains. Phylogenetically...