Open AccessGenetic Analysis of Noroviruses in Chiba Prefecture, Japan, between 1999 and 2004
Author(s) -
Morio Okada,
Tomoko Ogawa,
Ikuo Kaiho,
K. Shinozaki
Publication year - 2005
Publication title -
journal of clinical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.349
H-Index - 255
eISSN - 1070-633X
pISSN - 0095-1137
DOI - 10.1128/jcm.43.9.4391-4401.2005
Subject(s) - genotype , biology , outbreak , phylogenetic tree , norovirus , acute gastroenteritis , genetic diversity , virology , genetic analysis , veterinary medicine , genetics , gene , medicine , population , environmental health
Noroviruses (NVs) are common pathogens that consist of genetically divergent viruses that induce gastroenteritis in humans and animals. Between September 1999 and June 2004, 1,898 samples obtained from patients showing sporadic or outbreak gastroenteritis in Chiba Prefecture, Japan, were tested for NVs by reverse transcription-PCR. NVs were detected in 603 samples. Approximately 80% were positive for genogroup GII, 13% were positive for genogroup GI, and the remaining 7% were positive for both genogroups. Phylogenetic analysis showed that the GI and GII genogroups could be further divided into 13 and 16 genotypes (including new genotypes), respectively. The GII-4 genotype, which included five small genetic clusters (subtypes), was the most common in this study and was detected in approximately 40% of positive samples. The P2 regions of 10 strains belonging to each of the five GII-4 subtypes showed 5 to 18% amino acid diversity. The amino acidsubstitutions accumulated in the protruding (P) region during the 5-year study period. Our data suggest that highly variable NV strainsare circulating in Chiba Prefecture, with a high rate of genetic change observed during the 5-year study period.