SUBGROUPING OF RESPIRATORY SYNCYTIAL VIRUS-STRAINS FROM AUSTRALIA ANDPAPUA-NEW-GUINEA BY BIOLOGICAL AND ANTIGENIC CHARACTERISTICS

Strains of respiratory syncytial virus from 3 major areas of Australia and Papua New Guinea (PNG) were analyzed for variations in their anti genic and biological properties and in the molecular weights of their major structural proteins. Seventy-eight strains from infants and youn g children with LRI were collected from 1981-1984. The RSV season in t he Australian cities lasted from April through September, with major p eaks in July of each year, while the RSV season in tropical PNG was ye ar-round, with small peaks in March and October of each year coincidin g with excessive rainfall. Fifty-six strains were analyzed in detail; 40 were typed by time-resolved fluoroimmunoassay with monoclonal antib odies as group A strains and 16 were group B; both groups were concurr ent. Three children of one family had sequential RSV infections 13 mon ths apart, and the etiologic group A strain was identical both years i n terms of growth and antigenic properties with strain-specific ferret antisera; the second infection was milder in all three children. On a verage, the group A strains replicated considerably better than group B strains in HEp2 cells, producing 53% more syncytia and 99% higher in fectious virus titers in 31% less time in culture. Ten group A and B r eference strains exhibited the same growth patterns as the A and B reg ional strains, respectively. Differences in antigenicity as measured w ith hyperimmune antisera to prototype Long strain were even greater. G roup A strains exhibited a mean 68% greater IFA staining than B strain s, a 71% greater EIA reaction, and were neutralized to 69% higher seru m titers than B strains. Again, the reference A and B strains included as controls gave patterns identical to those of the regional strains. Finally, the P phosphoprotein had consistently higher molecular weigh t in A strains (mean 35 900) than B strains (mean 33 100). Small varia tions in the sizes of the F and G glycoproteins were not sufficient to suggest grouping on this basis.