Worldwide G-glycoprotein phylogeny of human respiratory syncytial virus (hRSV) group A sequences revealed diversification in major clades and genotypes over more than 50 years of recorded history. Multiple genotypes cocirculated during prolonged periods of time, but recent dominance of the GA2 genotype was noticed in several studies, and it is highlighted here with sequences from viruses circulating recently in Spain and Panama. Reactivity of group A viruses with monoclonal antibodies (MAbs) that recognize strain-variable epitopes of the G glycoprotein failed to correlate genotype diversification with antibody reactivity. Additionally, no clear correlation was found between changes in strain-variable epitopes and predicted sites of positive selection, despite both traits being associated with the C-terminal third of the G glycoprotein. Hence, our data do not lend support to the proposed antibody-driven selection of variants as a major determinant of hRSV evolution. Other alternative mechanisms are considered to account for the high degree of hRSV G-protein variability. H uman respiratory syncytial virus (hRSV) is recognized as the major cause of severe acute lower respiratory tract infections (ALRI) in infants and young children worldwide (1). hRSV causes annual epidemics, and reinfections are common throughout life, although they are usually less severe than the primary infections. hRSV is also an important cause of morbidity and mortality in the elderly and in adults with cardiopulmonary disease or with an impaired immune system (2). IMPORTANCE An unusual characteristic of the G glycoprotein of human respiratory syncytial virus (hRSV) is the accumulation of nonsynonymous (N) changes at higher rates than synonymous (S) changes, reaching dN/dS valueshRSV is an enveloped, nonsegmented, negative-sense RNA virus, classified in the genus Pneumovirus within the Paramyxoviridae family (for a recent review, see reference 3). The hRSV genome encodes 11 proteins, two of them being the major surface glycoproteins of the virus envelope. These are (i) the attachment (G) protein, which mediates binding of the virus to the cell surface (4), and (ii) the fusion (F) protein, which promotes fusion of the virus and cell membrane, allowing cell entry of the viral genome (5).The G protein is a type II glycoprotein synthesized as a 32-kDa polypeptide precursor of 297 to 310 amino acids (aa), depending on the strain, and modified posttranslationally by the addition of several N-linked oligosaccharides and multiple O-linked sugar chains (6). The G-protein ectodomain (from residue 67 to the C terminus) has a central conserved region (aa 163 to 189) that includes four Cys residues (residues 173, 176, 182, and 186), and it is essentially devoid of potential glycosylation sites. This conserved region is flanked by two highly variable mucin-like segments, very rich in Ser and Thr, that are potential sites of O glycosylation. The extensive glycosylation of the G protein shapes its reactivity with both murine monoclonal antibodies (M...

Partial sequences of the G protein gene of 33 isolates from antigenic group B of human respiratory syncytial virus were determined. Phylogenetic analysis indicated that the evolutionary pattern of group B viruses is similar to that previously described for isolates of antigenic group A, including worldwide distribution of related viruses and co-circulation of viruses from different lineages during the same epidemic. Dominance of AGM GA over UCM CU transitions was observed when G sequences of group B viruses were compared, as previously found in viruses from antigenic group A. Interestingly, differences in protein length, determined by the usage of alternative termination codons, were more pronounced in group B than in group A viruses. Changes in protein length correlated with the classification of viruses in different lineages. Thus, mutations that determined termination codon usage seem to have played an important role in the diversification of group B viruses.Human respiratory syncytial virus (HRSV) is the leading cause of severe lower respiratory tract infections in infants and very young children (Collins et al., 1996). The virus is distributed worldwide and in temperate climates outbreaks of HRSV infections occur yearly as sharp peaks of activity in winter months. This epidemiological pattern differs in tropical countries where HRSV infections are distributed throughout extended periods of time, mainly during the rainy seasons (Heirholzer et al., 1994). Although severe HRSV infections occur most frequently during infancy, there is growing evidence that HRSV is an important pathogen for the elderly

. Strain DENV3/5532 was found to display significantly higher replicative ability than DENV3/ 290 in monocyte-derived dendritic cells (mdDCs). In addition, compared to DENV3/290 results, mdDCs exposed to DENV3/5532 showed increased production of proinflammatory cytokines associated with higher rates of programmed cell death, as shown by annexin V staining. The observed phenotype was due to viral replication, and tumor necrosis factor alpha (TNF-␣) appears to exert a protective effect on virus-induced mdDC apoptosis. These results suggest that the DENV3/5532 strain isolated from the fatal case replicates within human dendritic cells, modulating cell survival and synthesis of inflammatory mediators.

During 5,230 trapping nights, 672 small mammals were trapped in the areas where most hantavirus pulmonary syndrome (HPS) cases occur in Uruguay. Yellow pygmy rice rats (Oligoryzomys flavescens) were the only rodents that showed evidence of antibodies to hantavirus, with a seroprevalence of 2.6%. The rodents were trapped in all the explored environments, and most of the seropositive rodents were found in habitats frequented by humans. Nucleotide sequences were obtained from four HPS case-patients and four yellow pygmy rice rats of the M genome segment. Sequence comparison and phylogenetic analysis showed that rodent-borne viruses and viruses from three HPS case-patients form a well-supported clade and share a 96.4% identity with the previously characterized Central Plata hantavirus. These results suggest that yellow pygmy rice rat (O. flavescens) may be the host for Central Plata, a hantavirus associated with HPS in the southern area of Uruguay.[