Surveillance of human calicivirus infection in diarrheal patients visiting enteric clinics in Beijing in winter, 2007-2008

Objective To determine the prevalence of human calicivirus infection among diarrheal patients who visited enteric clinics in winter in Beijing. Methods From December 2007 to March 2008, 271 diarrheal patients visiting enteric clinics were investigated in Beijing. Their fecal specimens were collected for the detection of human caliciviruses using the reverse transcription polymerase chain reaction (RT-PCR), and positive PCR products were cloned and sequenced. Results A total of 87 positive cases were detected among the 271 patients, with the positive rate of 32.10%, and 21 PCR products were randomly selected for sequencing. Compared with the nucleotide sequences of norovirus reference strains from GenBank, phylogenetic analysis showed that all of the 21 samples were norovirus other than sapovirus, including 16 isolate of norovirus GⅡ/4 (16/21, 76.19%), 1 isolate of norovirus GⅡ/6 (1/21, 4.76%), 1 of norovirus GⅡ/7 (1/21, 4.76%) and the other 3 of unidentified type (3/21,14.29%). Conclusion The infection rate of human calicivirus was relatively high among diarrheal patients visiting enteric clinics in winter in Beijing, and norovirus GII /4 was the predominant genotype.