Detection, quantitation, and phylogenetic analysis of noroviruses in Japanese oysters

• Published in: Applied and Environmental Microbiology Vol. 69; no. 10; pp. 5782 - 5786
• Main Authors: Nishida, T, Kimura, H, Saitoh, M, Shinohara, M, Kato, M, Fukuda, S, Munemura, T, Mikami, T, Kawamoto, A, Akiyama, M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.2003
• Subjects: Analysis; Animals; Biological and medical sciences; Caliciviridae; Capsid; Capsid Proteins - genetics; coat proteins; Crassostrea; Crassostrea gigas; Crassostrea nippona; food contamination; food microbiology; food pathogens; Fundamental and applied biological sciences. Psychology; genes; Genetics; genome; Japan; Marine; microbial contamination; Microbiology; molecular sequence data; Mollusca; Norovirus; Norovirus - classification; Norovirus - genetics; Norovirus - isolation & purification; Norwalk virus; nucleotide sequences; Ostreidae; Ostreidae - virology; Oysters; Phylogeny; Public Health Microbiology; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral - isolation & purification; Sequence Analysis, DNA; Shellfish - virology; Viruses; Japan; INW, Japan; Virus; Analysis method; Bivalvia; Oyster; Phylogeny; Invertebrata; Mollusca; Detection; Quantitative analysis
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.69.10.5782-5786.2003

Noroviruses (NVs) cause many cases of oyster- or clam-associated gastroenteritis in various countries. We collected 191 samples from Japanese oysters intended for raw consumption that had been harvested from the sea in two different areas between December 2001 and February 2002. To detect, quantitate, and phylogenetically analyze the NV genome in purified concentrates from the stomachs and digestive diverticula of these oysters, we amplified the NV capsid gene by reverse transcription-PCR. Phylogenetic analysis was performed by using the neighbor-joining method. We detected the NV genome in 17 of 191 oysters (9%). Phylogenetic analysis indicated genogroup I (Norwalk virus type) in 3 of the 17 oysters and genogroup II (Snow Mountain virus type) in the other 14. Both genogroups showed wide genetic diversity. To quantify the NV capsid gene in these oysters, we performed real-time PCR using genogroup-specific probes. More than 102 copies of the NV genome were detected in 11 of 17 oysters. The results suggested that about 10% of Japanese oysters intended for raw consumption harbored NVs, and more than 50% of those oysters in which NVs were detected had a large amount.