Genetic variability among group A and B respiratory syncytial viruses in Mozambique: identification of a new cluster of group B isolates

Respiratory syncytial virus (RSV) is the major cause of acute lower respira tory tract infection in children and vulnerable adults, but little is known regarding RSV infection in Africa. In this report, a recent RSV outbreak i n Mozambique was studied and results showed that 275 of 3192 (8.6%) nasopha ryngeal aspirates tested were RSV-positive by ELISA. RSV presents two antig enic groups (A and B) with a high genetic and antigenic variability between and within them. Analysis by a new RFLP assay of RT-PCR amplified N protei n gene products showed a higher prevalence of group B RSV than that of grou p A (85% versus 15%). However, genetic variability of the G protein gene wa s higher among group A RSV strains. The frequency and pattern of glycosylat ion sites were also quite different between both groups. In addition, two d ifferent phylogenetic clusters of Mozambican viruses were found within each group, but only sequences from cluster B-I were relatively distinct from p reviously described isolates. The implications of such differences in the a ntigenic and immunogenic characteristics of each group are discussed.