[Detection of HAV, SRSV and astrovirus genomes from native oysters in Chiba City, Japan].

SRSV, astrovirus in tvirus and HAV genomes were detected by RT-PCR in naturally grown oysters (total 112) collected in Chiba City bay, Japan, through a year from April, 1997 to March, 1998 and genogroup was typed by sequencing. SRSV positive products were detected by RT-PCR from 28 out of 112 oysters and all of them were grouped into G-II by sequencing. The highest incidence was observed in February, 1998. Furthermore, astrovirus positive products were detected sporadically from 15 out of 112 samples and the highest incidence was observed in January, 1998. On the other hand, HAV was detected from only 2 out of 112 and no adenovirus positive product was detected. The results indicated that both SRSV and astrovirus were predominantly distributed into naturally grown oysters in the winter season. SRSV and astrovirus seem to contribute mainly to the food-born outbreaks of gastroenteritis occurred by eating contaminated oysters as causative agents.