Respiratory syncytial virus epidemics: variable dominance of subgroups A and B strains among children, 1981-1986.

We examined the distribution of subgroups A and B strains from respiratory syncytial virus during five epidemic years from 1981 to 1986 in Huntington, West Virginia. Of 235 infants and children with respiratory syncytial virus infection, 211 had virus reisolated from frozen throat swab specimens for subgroup characterization by reactivity with a panel of monoclonal antibodies to the G, F, NP, M, and P proteins by using an enzyme immunoassay. We identified 160 (75.8%) strains as subgroup A and 51 (24.2%) as subgroup B. Strains of both subgroups were isolated in all years. Small, but approximately equal, numbers of subgroup B strains were isolated each epidemic year. By contrast, subgroup A strains occurred at least three times as often in all years except 1984-1985. The very low number of subgroup A strains isolated during the 1984-1985 epidemic gave dominance to subgroup B strains.