Genetic variability of subgroup A and B respiratory syncytial virus strains circulating in southwestern China from 2009 to 2011.

Human respiratory syncytial virus (RSV) is recognized as a leading pathogen responsible for severe respiratory infections in the pediatric population, particularly in infants and young children. A previous study by the same study group revealed that the RSV BA strain was prevalent in southwestern China in epidemic seasons from 2008 to 2009. The aim of this study was to investigate the epidemiology of RSV in the following two years, the genetic variability of the G gene, and mutations at the 276th amino acid in the fusion (F) protein of RSV strains. Nine BA substrains were found in 16 subgroup B viruses by phylogenetic analysis. The G gene of genotype BA was predicted to encode proteins with five different lengths. The findings indicate that subgroup A and B RSVs alternately circulate in southwestern China and that genotype BA strains appear to be the long-term circulating ones. These epidemiological data may help in future vaccine design and further investigation of G protein function.