Variable immune-driven natural selection in the attachment (G) glycoprotein of respiratory syncytial virus (RSV)

A maximum-likelihood analysis of selection pressures acting on the attachme nt (G) glycoprotein gene of respiratory syncytial virus (RSV) from humans ( HRSV) and bovines (BRSV) is presented. Six positively selected sites were i dentified in both group A and group B of HRSV, although only one site was c ommon between them, while no positively selected sites were detected in BRS V. All positively selected sites were located within the ectodomain of the G protein and showed some association with positions of immunoglobulin (Ig) epitopes and sites of O-glycosylation. These results suggest that immune ( antibody)-driven natural selection is an important determinant of RSV evolu tion and that this selection pressure differs among strains. The passage hi stories of RSV strains were also shown to affect the distribution of positi vely selected sites, particularly in HRSV B, and should be considered whene ver retrospective analysis of adaptive evolution is undertaken.