RESUMO
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.
Assuntos
Surtos de Doenças , Infecções por Vírus Respiratório Sincicial/epidemiologia , Vírus Sincicial Respiratório Humano/genética , Genótipo , Humanos , Epidemiologia Molecular , Dados de Sequência Molecular , Infecções por Vírus Respiratório Sincicial/virologia , Vírus Sincicial Respiratório Humano/isolamento & purificação , Uruguai/epidemiologiaRESUMO
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 AG+GA over UC+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.
Assuntos
Processamento Alternativo , Antígenos Virais/genética , Códon de Terminação , Evolução Molecular , Variação Genética , Proteína HN , RNA Viral , Vírus Sincicial Respiratório Humano/genética , Proteínas Virais/genética , Antígenos Virais/classificação , Humanos , Filogenia , Vírus Sincicial Respiratório Humano/classificação , Proteínas do Envelope Viral , Proteínas Virais/classificaçãoRESUMO
Enzyme immunoassays were developed to detect the presence of specific immunoglobulin E (IgE) antibodies and respiratory syncytial (RS) virus structural proteins in nasopharyngeal secretions in order to improve the knowledge on some aspects of the pathogenesis of severe acute lower respiratory tract infections caused by RS virus. These assays were used to analyze clinical specimens from children with RS virus-associated infections (bronchiolitis and pneumonia), and the findings were correlated with the patients' clinical symptoms. The results indicate the presence of specific IgE against the two external glycoproteins (G and F) and the absence of detectable IgE levels for the internal viral antigens. There was a correlation between the levels of IgE-specific antibodies and the amount of viral protein F in the secretions, indicating that the IgE response against the viral glycoproteins might be related to the antigen load. In addition, a correlation was found between higher levels of both viral protein F-specific IgE and F antigen with higher respiratory rates in children with pneumonia. These findings may be relevant because they suggest an association between the virus load and the immune response in the pathogenesis of RS virus infections.
Assuntos
Antígenos Virais/análise , Proteína HN , Imunoglobulina E/análise , Nasofaringe/microbiologia , Vírus Sinciciais Respiratórios/imunologia , Infecções por Respirovirus/imunologia , Proteínas Virais/análise , Anticorpos Antivirais/análise , Antígenos Virais/imunologia , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Estações do Ano , Proteínas do Envelope Viral , Proteínas Virais/imunologiaRESUMO
The occurrence of subgroup A and B strains of respiratory syncytial virus (RSV) was studied during three epidemic years, 1985 to 1987, in Uruguay. A set of monoclonal antibodies was selected according to their reactivity with local RSV isolates and used for the typing of RSV directly in nasopharyngeal cells by indirect immunofluorescence. Of 77 specimens, 69 could be typed as belonging to subgroup A or B, 5 could not be typed with the restricted set of monoclonal antibodies employed, and 3 reacted with both subgroup-specific antibodies. In 1985 and 1986 subgroup A predominated, accounting for 65.7% of all typed specimens, but in 1987 subgroup B surpassed subgroup A, accounting for 82.4% of the samples.