RESUMO
The gene encoding the protein VP7 that induces the major neutralizing response has been sequenced from 34 human rotaviruses isolated from children with acute diarrhea in Montevideo (Uruguay) over a 4-year period (1996-1999). These sequences were analyzed and compared to representative corresponding sequences available on databases. In most years, serotype G1 was present as the single serotype, except in 1999 when serotypes G1 and G4 were present simultaneously. Two G1 VP7 lineages were identified. Serotype G2 was present in 1997. The G4 isolates are grouped with Argentine strains and emerged during 1998 in a recently defined sublineage. Neither serotype G3 nor the emerging serotype G9 were isolated during the study. Antigenic domains of isolates and of representative reference strains of each serotype were compared. Sequences of strains isolated during the same year, showed a high degree of homology among strains belonging to the same serotype.
Assuntos
Antígenos Virais , Proteínas do Capsídeo/genética , Diarreia/epidemiologia , Variação Genética , Infecções por Rotavirus/epidemiologia , Rotavirus/genética , Sequência de Aminoácidos , Proteínas do Capsídeo/química , Diarreia/virologia , Humanos , Lactente , Dados de Sequência Molecular , Filogenia , Rotavirus/classificação , Rotavirus/isolamento & purificação , Infecções por Rotavirus/virologia , Análise de Sequência de DNA , Uruguai/epidemiologiaRESUMO
Rotavirus is a nonenveloped virus with a three-layered capsid. The inner layer, made of VP2, encloses the genomic RNA and two minor proteins, VP1 and VP3, with which it forms the viral core. Core assembly is coupled with RNA viral replication and takes place in definite cellular structures termed viroplasms. Replication and encapsidation mechanisms are still not fully understood, and little information is available about the intermolecular interactions that may exist among the viroplasmic proteins. NSP2 and NSP5 are two nonstructural viroplasmic proteins that have been shown to interact with each other. They have also been found to be associated with precore replication intermediates that are precursors of the viral core. In this study, we show that NSP5 interacts with VP2 in infected cells. This interaction was demonstrated with recombinant proteins expressed from baculovirus recombinants or in bacterial systems. NSP5-VP2 interaction also affects the stability of VP6 bound to VP2 assemblies. The data presented showed evidence, for the first time, of an interaction between VP2 and a nonstructural rotavirus protein. Published data and the interaction demonstrated here suggest a possible role for NSP5 as an adapter between NSP2 and the replication complex VP2-VP1-VP3 in core assembly and RNA encapsidation, modulating the role of NSP2 as a molecular motor involved in the packaging of viral mRNA.
Assuntos
Antígenos Virais , Proteínas do Capsídeo/fisiologia , Rotavirus/fisiologia , Proteínas Virais/fisiologia , Montagem de Vírus , Proteínas do Capsídeo/análise , Proteínas do Capsídeo/química , Testes de Precipitina , Proteínas Virais/análiseRESUMO
In vivo replication of rotaviruses is generally limited to enterocytes. Because of this restriction, most blood circulating rotavirus-specific B cells are hypothesized to originate in Peyer's patches and should express the intestinal homing receptor alpha4beta7. To test this hypothesis in humans, we used a flow cytometry assay that identifies antigen-activated (IgD-) B cells (CD19+) that express surface rotavirus-specific immunoglobulin. With this assay we could detect rotavirus-specific B cells in both children and adults with an acute rotavirus (RV) infection. Staining with an anti-alpha4beta7 monoclonal antibody, we could determine that B cells that express rotavirus-specific surface immunoglobulin predominantly express alpha4beta7. The response of rotavirus-specific antibody-secreting cells in the peripheral blood of children and adults with acute rotavirus infection was also studied by ELISPOT. The antibody-secreting cells of children were mainly of the IgM isotype, while the antibody-secreting cells of adults were predominantly of the IgA and IgG isotype. alpha4beta7+ and alpha4beta7- subsets of peripheral blood mononuclear cells were purified using paramagnetic beads and then tested in the ELISPOT assay. Rotavirus-specific antibody-secreting cells were predominantly present in the alpha4beta7+ subpopulation. The flow cytometry assay we have described will permit future studies to characterize the phenotype of virus-specific B cells and could be useful in the study of the immunogenicity and protective efficacy of RV vaccines and the identification of markers of protective immunity.
Assuntos
Linfócitos B/imunologia , Integrinas/análise , Infecções por Rotavirus/imunologia , Rotavirus/imunologia , Adolescente , Adulto , Idoso , Anticorpos Antivirais/análise , Células Produtoras de Anticorpos/fisiologia , Linfócitos B/química , Diarreia/imunologia , Humanos , Imunofenotipagem , Lactente , Integrinas/fisiologia , Pessoa de Meia-Idade , Receptores de Antígenos de Linfócitos B/análiseAssuntos
Humanos , Adulto , Criança , Infecções/diagnóstico , Infecções/imunologia , Infecções/metabolismo , LinfócitosRESUMO
Una reflexión sobre el papel de la retórica en la evolución de la cultura occidental, sobre las relaciones del pasado con la gramática y la dialéctica, sus lazos actuales con la ling³ística, la lógica y la semiología, a estos enfoques históricos y filosóficos responden en distintos niveles y según orientaciones diversas las contribuciones que forman este volumen