Sequence analysis of G glycoprotein gene of human respiratory syncytial virus

Objective To understand the variation of Gglycoprotein gene of human respiratory syncytial virus(HRSV)obtained from Sichuan in 2010and determine the dominant genotypes.Methods Gglycoprotein gene of seven cases of subtype A and eleven cases of subtype B of HRSV were amplified by RT-PCR and sequenced.The phylogenetic trees were constructed to determine the subtype of samples.And then,the genetic variations of the second hypervariable region of Gglycoprotein gene were studied.Results The nucleotide genetic distances of G glycoprotein gene in subtype A and subtype B HRSV were 0.022±0.005and 0.073±0.010,respectively. Transitions were more prevalent than transversions,GA+AG were the most frequent transitions detected among group A viruses,while UC+CU transitions were the most among group B.Phylogenetic analyses demonstrated that 7subtype A virus could be clustered into one genotype,genotype GA2,and 11subtype B virus could be clustered into two genotypes,GB2and BA.The length of Gprotein gene in group A was all 298aa,but in group B included 295aa,312aa and 315aa.Selective pressure was purifying selection in both subtypes.9positively selected sites in group A and 1in group B on the second hypervariable region of G protein were identified.Conclusion GA2,GB2 and BA were the main genotype.The changes may favor virus escape from the host immune response including the variation of the Gprotein gene length,frequency of nucleotide changes and selective pressure.