RESUMO
Immunovirological studies suggest that human respiratory syncytial virus may well be composed of five structural proteins as are other members of the Paramyxoviridae family: the two external membrane glycoproteins H (90 000) and Fo (F1, 49 000; F2, 20 000; disulfide linked), the internal membrane protein M (34 000), the nucleoprotein N (42 000), and a protein (78 000) designated P that could be the equivalent of the polymerase of the morbillivirus and paramyxovirus genus. Neutralizing monoclonal antibodies showed, by immunoprecipitation and immunoblotting, that the fusion protein carries neutralizing epitopes. One monoclonal antibody, which shows a high neutralizing titer, immunoblotted directly with the F1 fragment (49 000) of the fusion protein. Analysis in mice of the immunogenicity of the structural proteins separated on sodium dodecyl sulphate gels indicated that, under our conditions, only the fusion protein dimer Fo and its F1 fragment were capable of inducing neutralizing antibodies.
Assuntos
Vírus Sinciciais Respiratórios/análise , Proteínas Virais/análise , Animais , Anticorpos Monoclonais , Anticorpos Antivirais , Especificidade de Anticorpos , Capsídeo/análise , Capsídeo/imunologia , Epitopos/imunologia , Imunofluorescência , Cobaias , Humanos , Imunoeletroforese , Técnicas de Imunoadsorção , Camundongos , Camundongos Endogâmicos BALB C , Testes de Neutralização , Vírus Sinciciais Respiratórios/imunologia , Proteínas do Core Viral/análise , Proteínas do Core Viral/imunologia , Proteínas do Envelope Viral/análise , Proteínas do Envelope Viral/imunologia , Proteínas Virais de Fusão , Proteínas da Matriz Viral , Proteínas Virais/imunologiaRESUMO
With a sensitive indirect immunofluorescent technique, we studied the antibody response to Candida albicans in 150 human amniotic fluid (AF) specimens at 15 to 18 weeks' gestation. Specific IgG was detected in 94.7% of the samples and specific IgA, in 98%, while 1.3% were negative in both tests. A comparison of the mean ratio of anticandidal titers (IgA/IgG) in AF and human serum indicated a predominance of IgA activity in AF and the reverse in serum (2.01 versus 0.66, p less than 0.001). There was no correlation between IgG and corresponding IgA titers, which supports the fetal origin of IgA. Humoral immunity alone had no discernible influence on the growth of C. albicans in midtrimester AF. It is suggested that the synthesis of specific IgA is genetically determined because it presumably offers some functional advantage over transmitted maternal IgG in the local defensive mechanisms of the amniotic cavity.