RESUMO
To analyse the effect of strain-specific sequence variation on the antigenic properties of the protein encoded by the open reading frame 3 (ORF 3) of hepatitis E virus (HEV), two sets of short overlapping peptides spanning amino acids 91 to 123 of this protein from Burmese and Mexican strains were synthesized and tested with sera obtained from outbreaks of enterically transmitted non-A, non-B hepatitis in three different regions of the world (Mexico, Turkmenistan and Kenya). The data suggest strain-specific variation in the antigenic reactivity of the ORF 3 protein. The C-terminal region of this protein contains several antigenic epitopes located in the most variable positions. Individual sera were found to interact with different groups of epitopes from each set of peptides. The antigenic epitopes of the Mexican strain appear to be less conformation-dependent than those of the Burmese strain. The most immunoreactive epitope of the ORF 3 protein from the Mexican strain was localized at amino acid positions 95 to 101. The ORF 3 protein of the Burmese strain contains an immunodominant epitope at amino acid positions 112 to 117. Some of these short peptides may be useful for the development of a diagnostic assay to discriminate between the Burmese and Mexican strains.
Assuntos
Variação Genética/genética , Vírus da Hepatite E/química , Epitopos Imunodominantes/análise , Proteínas Virais/química , Sequência de Aminoácidos , Vírus da Hepatite E/genética , Vírus da Hepatite E/imunologia , Humanos , Epitopos Imunodominantes/genética , México , Dados de Sequência Molecular , Mianmar , Fases de Leitura Aberta/genética , Proteínas Virais/genética , Proteínas Virais/imunologiaRESUMO
Antibodies against hepatitis E virus (HEV) were detected in sera by a synthetic peptide-based enzyme immunoassay (EIA) from different populations in Venezuela. Antibodies against HEV were found in 1.6% (3/184) of urban pregnant woman (Caracas), in 3.9% (8/204) of rural populations (San Camilo, Edo Apure), and in 5.4% (12/223) of rural Amerindians (Padamo, Edo Amazonas). Positivity was confirmed by a neutralization EIA based on the use of competing soluble free peptides. The prevalence of antibodies in the Amerindian group was significantly higher than in urban pregnant women. No relation was found between age and HEV prevalence in rural populations. Three of 21 positive sera were also weakly positive by Western blot for IgM antibodies. This result, together with the low optical density values observed by EIA, suggested that the presence of antibodies in these sera reflects past infections. Based on these results, Venezuela does not seem to be highly endemic for hepatitis E. This is the first report of serological evidence of infection by HEV in South America.
Assuntos
Anticorpos Antivirais/sangue , Vírus da Hepatite E/imunologia , Hepatite E/epidemiologia , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Hepatite E/etnologia , Humanos , Técnicas Imunoenzimáticas , Imunoglobulina M/sangue , Indígenas Sul-Americanos , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/imunologia , Gravidez , Complicações Infecciosas na Gravidez/epidemiologia , Complicações Infecciosas na Gravidez/imunologia , Complicações Infecciosas na Gravidez/microbiologia , Prevalência , População Rural , Estudos Soroepidemiológicos , População Urbana , Venezuela/epidemiologiaRESUMO
A series of synthetic peptides derived from proteins encoded by open reading frames 2 and 3 (ORF2 and ORF3) of the hepatitis E virus was used in an enzyme immunoassay to determine the localization of epitopes in these proteins. Five peptides spanning almost the entire ORF3 protein sequence and 12 peptides from the ORF2 protein were synthesized. Serum samples collected from outbreaks in three different regions of the world (Turkmenistan, Kenya, and Mexico) were analyzed by a peptide-based enzyme immunoassay. Primary analysis of the peptides was accomplished with the use of serum samples obtained from Middle Asia. Four of 5 peptides from the ORF3 protein and 4 of 12 peptides from the ORF2 protein specifically reacted with antibody from sera of HEV-infected patients. Peptides representing immunodominant epitopes were used for the analysis of serum samples from outbreaks in Kenya and Mexico. The data indicate that these synthetic peptides may be used to develop a diagnostic test to detect antibody to the hepatitis E virus.