Molecular Comparison of VP7 and VP4 genes of Porcine Group A Rotavirus from 1980 to 2006 in Japan

H. TSUNEMITSU; S. SERENA; A. MIYAZAKI; M. YOSHII; N. HATTORI

Wuhan, China

Congreso; The 3rd Congress of the Asian Pig Veterinary Society; 2007

Molecular comparison of VP7 and VP4 genes of porcine group A rotaviruses from 1980 to 2006 in Japan H. Tsunemitsu, S. Serena, A. Miyazaki, M. Yoshii, and N. Hattori. Research Team for Viral Diseases, National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan Keywords: group A rotavirus, VP7, VP4, nucleotide sequence, pigs Introduction Group A rotaviruses (GARs) are the major cause of acute diarrhea in the young of many mammalian and avian species, including piglets. The two outer capsid proteins of GARs, VP7 and VP4, form the basis for a dual classification system based on VP7 (G) and VP4 (P) genotypes. At least 15 VP7 and 26 VP4 genotypes have been described to date. Previous studies in the US and Europe have identified four main VP7 genotypes (G3, G4, G5, and G11) and two main VP4 genotypes (P[6] and P[7]) in porcine GARs. Here, we investigated the prevalence of VP7 and VP4 genotypes of porcine GARs detected in diarrheal feces of piglets from 1980 to 2006 in Japan. Materials and methods A total 38 porcine GAR strains (isolates or feces) detected at 34 farms in Japan from 1980 to 2006 were examined for VP7 and VP4 genotypes by RT-PCR and direct sequencing. The PCR products were then sequenced directly by cycle sequencing with an auto sequencer. Results Among VP7 genotypes, the five GAR strains in 1980 were classified into two G1, one G3, one G4, and one G5 types. The VP7 sequence of one G1 strain was most closely related to that of human strain AU19 (97.9% nt and 98.8% aa identity) detected in the late 1980s in a patient with severe diarrhea in Japan. The 33 GAR strains between 2000 and 2006 were classified into 1 G1, 4 G3, 4 G4, 12 G5, and 12 G9 types. The VP7 genes of these 12 porcine G9 strains were more closely related to those of human G9 strains reemerging globally since the mid-1990s than to those in the mid-1980s. Regarding VP4 genotypes, the five GAR strains in 1980 were classified into one P[6], two P[7], one P[13], and one P[23] types. Twenty-seven GAR strains between 2000 and 2006 could be classified into nine P[6], four P[7], six P[13], and eight P[23] types. The VP4 sequences of two P[6] strains in 2002 shared closer sequence identity with the human AU19 strain than with porcine P[6] strains. Discussion and conclusion These results indicate that the prevalence of VP7 and VP4 genotypes of porcine GARs in Japan differs from that in the US and Europe, and has changed over the past quarter-century. Of note, the G9 genotype is predominant in recent porcine GARs in Japan. The VP7 genes of porcine G9 strains and those of some human G9 strains detected recently may have a common progenitor. In addition, the human AU19 strain might be a human-porcine reassortant, or of porcine origin as a whole virion. Interspecies transmission of GARs between humans and pigs may occur more frequently than previously thought.   Acknowledgment This study was supported in part by grants from the Japan International Cooperation Agency and Ministry of Agriculture, Forestry and Fisheries of Japan.