Circulation patterns of group A and B human respiratory syncytial virus genotypes in 5 communities in North America

Human respiratory syncytial virus (HRSV) is a major cause of serious lower respiratory tract illness in infants, young children, and the elderly. To c haracterize the circulation patterns of HRSV strains, nucleotide sequencing of the C-terminal region of the G protein gene was performed on 34-53 isol ates obtained from 5 communities during 1 epidemic year, representing disti nct geographical locations in North America. Phylogenetic analysis revealed that 5-7 HRSV genotypes, including 1 or 2 predominant strains, circulated in each community. The patterns of genotypes were distinct between communit ies, and less diversity was seen between strains of the same genotype withi n than between communities. These findings are consistent with HRSV outbrea ks' being community based in nature, although transmission of viruses betwe en communities may occur. Several strains are probably introduced or circul ate endemically in communities each year, and local factors-possibly immuni ty induced by previous years) strains-determine which strains predominate d uring an HRSV season.