Genetic variability among group A and B respiratory syncytial viruses in Mozambique: identification of a new cluster of group B isolates.
ABSTRACT Respiratory syncytial virus (RSV) is the major cause of acute lower respiratory tract infection in children and vulnerable adults, but little is known regarding RSV infection in Africa. In this report, a recent RSV outbreak in Mozambique was studied and results showed that 275 of 3192 (8.6%) nasopharyngeal aspirates tested were RSV-positive by ELISA. RSV presents two antigenic 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 protein gene products showed a higher prevalence of group B RSV than that of group A (85% versus 15%). However, genetic variability of the G protein gene was higher among group A RSV strains. The frequency and pattern of glycosylation sites were also quite different between both groups. In addition, two different phylogenetic clusters of Mozambican viruses were found within each group, but only sequences from cluster B-I were relatively distinct from previously described isolates. The implications of such differences in the antigenic and immunogenic characteristics of each group are discussed.
Article: Positive selection results in frequent reversible amino acid replacements in the G protein gene of human respiratory syncytial virus.[show abstract] [hide abstract]
ABSTRACT: Human respiratory syncytial virus (HRSV) is the major cause of lower respiratory tract infections in children under 5 years of age and the elderly, causing annual disease outbreaks during the fall and winter. Multiple lineages of the HRSVA and HRSVB serotypes co-circulate within a single outbreak and display a strongly temporal pattern of genetic variation, with a replacement of dominant genotypes occurring during consecutive years. In the present study we utilized phylogenetic methods to detect and map sites subject to adaptive evolution in the G protein of HRSVA and HRSVB. A total of 29 and 23 amino acid sites were found to be putatively positively selected in HRSVA and HRSVB, respectively. Several of these sites defined genotypes and lineages within genotypes in both groups, and correlated well with epitopes previously described in group A. Remarkably, 18 of these positively selected tended to revert in time to a previous codon state, producing a "flip-flop" phylogenetic pattern. Such frequent evolutionary reversals in HRSV are indicative of a combination of frequent positive selection, reflecting the changing immune status of the human population, and a limited repertoire of functionally viable amino acids at specific amino acid sites.PLoS Pathogens 02/2009; 5(1):e1000254. · 9.13 Impact Factor
Article: Genetic and antigenic variability of human respiratory syncytial virus (groups a and b) isolated over seven consecutive seasons in Argentina (1995 to 2001).[show abstract] [hide abstract]
ABSTRACT: The genetic and antigenic variability of human respiratory syncytial virus (HRSV) strains isolated in Buenos Aires from 1995 to 2001 was evaluated by partial nucleotide sequencing of the G gene and enzyme-linked immunosorbent assay analysis with anti-G monoclonal antibodies. Phylogenetic analyses showed that 37 group A strains clustered into five genotypes, whereas 20 group B strains clustered into three genotypes. Group A showed more genetic variability than group B. A close correlation between genotypes and antigenic patterns was observed. Changes detected in the G protein of viruses from both groups included (i) amino acid substitutions and(ii) differences in protein length due to either changes in stop codon usage or sequence duplications. Three B strains from 1999 exhibited a duplication of 20 amino acids, while one B strain from 2001 had 2 amino acids duplicated. The comparison among Argentinean HRSV strains and viruses isolated in other geographical areas during different epidemics is discussed.Journal of Clinical Microbiology 06/2005; 43(5):2266-73. · 4.15 Impact Factor
[show abstract] [hide abstract]
ABSTRACT: Genotypes of Human respiratory syncytial virus (HRSV) of group B from Uruguay were assigned to strains isolated during 1999 and 2001 outbreaks and others formerly reported isolated in the period 1989-1996. The nucleotide sequences of the C-terminal portion of the G protein were compared to sequences representative of previously defined HRSV genotypes. Most Uruguayan strains clustered into five of the previously identified genotypes. Nine isolates clustered in two genotypes named URU1 and URU2 which were not described up to present. Two of the analyzed sequences isolated in 2001 have a six nucleotide duplication that is discussed in terms of HRSV variability.Archives of Virology 04/2005; 150(3):603-9. · 2.11 Impact Factor