GII.4 Sydney_2012 norovirus infection in immunocompromised patients in Beijing and its rapid evolution in vivo

To study the epidemiology and evolution of norovirus (NoV) in immunocompromised patients in a tertiary hospital in China. Stool specimens were collected from 131 hospitalized patients presenting with diarrhea from July 1, 2012, to June 30, 2013, and were tested for NoV using RT-PCR. RT-PCR was performed to amplify the complete capsid genome for a series of samples from chronic diarrhea patients, and nucleotide and amino acid changes were analyzed. There were nine NoV-positive patients among 124 immunocompromised patients (7.3%); all nine were infected with GII.4 Sydney_2012 strain. In three chronic diarrhea patients, the GII.4 Sydney_2012 strains accumulated 19, 18, and eight nucleotide mutations within 110, 113, and 22 days, respectively, most were non-synonymous. The greatest number of stable amino acid mutations was 10 in patient 2; eight stable mutations (including three in antigenic sites) occurred while the patient was asymptomatic and shedding the virus. GII.4 Sydney_2012 strain tends to undergo stable mutations during the asymptomatic shedding phase and may generate new variants in chronic diarrhea patients. (c) 2015 Wiley Periodicals, Inc.Molecular Epidemiology of New Norovirus Strain-GII.4 Sydney in Beijing [RDB2013-06]; Peking University People's Hospital Research and Development FundsSCI(E)PubMedARTICLEgaoyan6384@163.com2224-2338