Assuntos
Neoplasias das Glândulas Sudoríparas/metabolismo , Siringoma/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Fosforilação , Proteínas Proto-Oncogênicas c-kit/metabolismo , Neoplasias das Glândulas Sudoríparas/patologia , Siringoma/patologiaRESUMO
The glycoprotein B (gB) is highly conserved among distinct human herpesvirus 7 (HHV-7) strains. Similarly to other herpesvirus glycoproteins, gB has been assumed to induce a specific human immune response. However, it did not appear as an immunodominant protein in conventional immunoblot assays. Recombinant gB, obtained from either Escherichia coli or baculovirus expression systems, did react specifically with HHV-7-seropositive sera, and the main corresponding epitopes were located in its N-terminal part. A 24-amino-acid peptide, corresponding to a predicted hydrophilicity peak and presenting no extensive homology with other betaherpesvirus glycoproteins, was selected in this region at positions 129 to 152 of the gB sequence. When tested by enzyme-linked immunosorbent assay (ELISA), this peptide specifically reacted with HHV-7-seropositive sera. This reactivity was significantly inhibited by the preincubation of sera with the peptide itself, lysates of gB-expressing cells, or lysates of HHV-7-infected cells. The reactivity was not significantly modified when sera were preincubated with lysates of either human cytomegalovirus (HCMV)- or HHV-6-infected cells. In cross-sectional studies including both children and adults, 49 out of 61 serum samples (80%) were found to be positive by HHV-7 ELISA, independent of their reactivity to HCMV. A longitudinal serological study of 17 children during the first 4 years of life showed that the level of ELISA-detected antibodies significantly decreased within a few weeks after birth and then increased in the following months, likely reflecting, respectively, the loss of maternal antibodies and the occurrence of seroconversion. These results demonstrate that gB peptide ELISA might be a useful tool for the serological study of HHV-7 infection.
Assuntos
Anticorpos Antivirais/imunologia , Antígenos Virais/imunologia , Herpesvirus Humano 7/imunologia , Proteínas do Envelope Viral/imunologia , Adulto , Anticorpos Antivirais/sangue , Pré-Escolar , Ensaio de Imunoadsorção Enzimática , Humanos , Soros Imunes/imunologia , Immunoblotting , Lactente , Peptídeos/síntese química , Peptídeos/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Infecções por Roseolovirus/diagnóstico , Infecções por Roseolovirus/imunologia , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/genéticaRESUMO
The analysis of three human herpesvirus-7 (HHV-7) genes encoding phosphoprotein p100, glycoprotein B and major capsid protein respectively had previously shown the existence of distinct gene alleles, leading to the concept of HHV-7 variants. We have analysed the distribution of HHV-7 variants among 297 distinct subjects who belonged to different human populations from Africa, Asia, Europe and America. Two variants, designated Co1 and Co2, were found in 52% and 20% of studied subjects. Ten other variants, designated Co3-Co12, were less frequent and classified into two groups related to Co1 and Co2 respectively. While the former group was ubiquitous and the most frequent in Africa and Asia, the latter one was predominantly found in European and Mongol populations. Despite the high stability of the HHV-7 genome, a few nucleotide substitutions at precise positions define distinct variants which, to some extent, behave as markers of human populations.