| Summary: | 碩士 === 臺灣大學 === 醫學檢驗暨生物技術學研究所 === 95 === Human norovirus (NoV) causes gastroenteritis in humans in all age groups. NoV is transmitted through fecal contamination of food and water, and secondary person-to-person spread is common. Annual epidemics cause severe morbidity and even mortality, especially in developing countries. In recent years several naturally occurring recombinant NoVs have been reported around the world. Considering the fact that recombination occur much more often than it was thought to be, further study of the diversity and ongoing recombination of NoV may bring tremendous assistance for epidemiological studies and more importantly bring medical and healthcare attention for diminishing worldwide epidemics.
In this study the full-length genome of nine norovirus recombinants, isolated from stool specimens from 2002, 2003, and 2006 in Taiwan. Three PCR fragments covering the full-length genome were obtained for eight of the isolates. After the nucleotide sequences were determined, the relationships among different noroviruses (NoVs) in different genes were studied by phylogenetic analysis. The recombination break points were revealed by SimPlot analysis. According to the polymerase gene-based phylogenetic analysis, five isolates Taipei/0212/2003/TW, Taipei/2339/2002/TW, Taipei/0089/2003/TW, Taipei/0510/2002/TW, and Taipei/1969/2002/TW belonged to the recombinants with the GIIb polymerase gene. By capsid gene-based phylogenetic analysis, the above described GIIb polymerase recombinants clustered onto two distinct genotypes, Taipei/0089/2003/TW Taipei/0510/2002/TW, Taipei/1969/2002/TW, and Taipei/0212/2003/TW clustered with GII/3 strains, Taipei/2339/2002/TW clustered with GII/2 strains. Three isolates Taipei/0760/2002/TW, Taipei/1047/2006/TW, and Taipei/0898/2006/TW, clustered with GII/12 and GII/10 strains and shared 98% identity in polymerase gene. According to the capsid gene-based analysis, Taipei/0760/2002/TW, Taipei/1047/2006/TW, and Taipei/0898/2006/TW clustered with GII/10, GII/12, and GII/4 strains, respectively. Taken together, these results confirmed the existence of naturally occurring recombinant NoVs in Taiwan and this is the first evidence of naturally occurring recombinant NoV infection in Taiwan.
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