Genetic variation of human respiratory syncytial virus among children with fever and respiratory symptoms in Shanghai, China, from 2009 to 2012.

Human respiratory syncytial virus (HRSV) of genus Pneumovirus is one of the most common pathogens causing severe acute lower respiratory tract infection in infants and children. No information on the genotype distribution of HRSV is available in East China (e.g. Shanghai). From August 2009 to December 2012, 2407 nasopharyngeal swabs were collected from outpatient children with fever and respiratory symptoms in Shanghai. HRSV infection was determined using a multiplex RT-PCR assay. The second hypervariable region (HVR2) of G protein gene of HRSV was amplified and sequenced from HRSV positive samples. Genotypes were characterized by phylogenetic analyses. Of 2407 nasopharyngeal samples, 184 (7.6%) were tested as HRSV positive. From 160 positive subjects with sufficient nasopharyngeal samples, 69 HVR2 sequences were obtained by RT-PCR and sequencing. Three HRSV epidemic seasons were observed from August 2009 to December 2012, and an extreme outbreak of HRSV occurred in the 2009-2010 epidemic season. A genotype shift of predominant HRSV strains from B group in the 2009-2010 epidemic season to group A in the subsequent epidemic seasons was observed. Ten HRSV genotypes, including four group A genotypes NA1, NA3, NA4, and ON1, and six group B genotypes BA9, BA10, SAB4, CB1, BAc, and BA?, were detected in Shanghai. Seven genotypes (NA1, BA9-10, SAB4, CB1, BAc and BA?) were found in the 2009-2010 epidemic season. The co-circulation of multiple genotypes was associated with the extreme outbreak of HRSV among children with fever and respiratory symptoms in the 2009-2010 epidemic season.