The entire nucleotide sequence of the G gene of three human respiratory syncytial virus (HRSV) isolates (antigenic group B) has been determined. These three viruses (named BA viruses) were isolated in Buenos Aires in 1999 from specimens collected in different hospitals and at different dates. BA viruses have an exact duplication of 60 nucleotides in the G gene, starting after residue 791. This duplication is flanked by a repeat of four nucleotides (GUGU) and can fold into a relatively stable secondary structure. These features suggest a possible mechanism for the generation of a duplicated G segment. The predicted polypeptide is lengthened by 20 amino acids (residues 260-279) and this is reflected in the slower electrophoretic mobility of the G protein precursor of BA viruses compared with related viruses. The changes reported here expand the examples of drastic genetic alterations that can be introduced into the G protein sequence of HRSV while it replicates in its natural host.

. Phylogenetic analysis indicated that BA sequences with that duplication shared a common ancestor (dated about 1998) with other HRSV G sequences reported worldwide after 1999. The duplicated nucleotide sequence was an exact copy of the preceding 60 nucleotides in early viruses, but both copies of the duplicated segment accumulated nucleotide substitutions in more recent viruses at a rate apparently higher than in other regions of the G protein gene. The evolution of the viruses with the duplicated G segment apparently followed the overall evolutionary pattern previously described for HRSV, and this genotype has replaced other prevailing antigenic group B genotypes in Buenos Aires and other places. Thus, the duplicated segment represents a natural tag that can be used to track the dissemination and evolution of HRSV in an unprecedented setting. We have taken advantage of this situation to reexamine the molecular epidemiology of HRSV and to explore the natural history of this important human pathogen.

A collection of 165 adenovirus strains isolated from nasopharyngeal aspirates of children hospitalized for acute lower respiratory infection in Argentina, Chile, and Uruguay between 1991 and 1994 was studied by restriction enzyme analysis (work performed in the Department of Virology, University of Umeå). Of the isolates, 71% (n = 117) were identified as members of subgenus B. Of these, 101 (61.2%) corresponded to genome type 7h, four (2.4%) to genome type 3p2, four (2.4%) to genome type 11a, one (0.6%) to genome type 7b, and one (0.6%) to genome type 7c. Two isolates that were neutralized as serotype 3 and four isolates that were neutralized as serotype 7 exhibited novel BamHI cleavage profiles corresponding to three new genome types denominated 3x, 7i, and 7j. Subgenus C members represented 28.5% of all typed isolates. Five different genome types of Ad1, seven genome types of Ad2, and three genome types of Ad5 were identified of, which two, two, and one, respectively, were found to correspond to new DNA variants. Only one isolate (0.6%) corresponded to Ad4 of subgenus E. Ad7h was isolated from 17 of the 18 fatal cases recorded among the patients included in the study.

BackgroundHuman respiratory syncytial virus (RSV) is the leading cause of respiratory tract infections in children globally, with nearly all children experiencing at least one infection by the age of two. Partial sequencing of the attachment glycoprotein gene is conducted routinely for genotyping, but relatively few whole genome sequences are available for RSV. The goal of our study was to sequence the genomes of RSV strains collected from multiple countries to further understand the global diversity of RSV at a whole-genome level.MethodsWe collected RSV samples and isolates from Mexico, Argentina, Belgium, Italy, Germany, Australia, South Africa, and the USA from the years 1998-2010. Both Sanger and next-generation sequencing with the Illumina and 454 platforms were used to sequence the whole genomes of RSV A and B. Phylogenetic analyses were performed using the Bayesian and maximum likelihood methods of phylogenetic inference.ResultsWe sequenced the genomes of 34 RSVA and 23 RSVB viruses. Phylogenetic analysis showed that the RSVA genome evolves at an estimated rate of 6.72 × 10-4 substitutions/site/year (95% HPD 5.61 × 10-4 to 7.6 × 10-4) and for RSVB the evolutionary rate was 7.69 × 10-4 substitutions/site/year (95% HPD 6.81 × 10-4 to 8.62 × 10-4). We found multiple clades co-circulating globally for both RSV A and B. The predominant clades were GA2 and GA5 for RSVA and BA for RSVB.ConclusionsOur analyses showed that RSV circulates on a global scale with the same predominant clades of viruses being found in countries around the world. However, the distribution of clades can change rapidly as new strains emerge. We did not observe a strong spatial structure in our trees, with the same three main clades of RSV co-circulating globally, suggesting that the evolution of RSV is not strongly regionalized.