Dados do Trabalho

Título

Validation of a method for the detection of anti-hepatitis E virus IgG antibodies in swine

Introdução

Immunodiagnostic tests for HEV in humans are not available in Brazil and the investigation of HEV in swine may require the use of a method adapted from the ELISA protocols used for humans.

Objetivo (s)

To validate a method for determining the anti-HEV IgG antibody in pig.

Material e Métodos

Different strategies were used to predict linear B-cell epitopes of HEV: literature review in PubMed, search in a specialized database using the Immune Epitope Database and Analysis Resource (IEDB), and the use of an immunoinformatics tool on the web Prediction of linear potential B-cell epitopes (BepiPred). According to BepiPred, an epitope threshold of 0.4 would give a presumed sensitivity of 93%. The minimum length of 14 amino acids was used to filter out the antigenic regions. The epitopes identified by the three strategies were mapped to the reference sequence of the HEV-1 strain of Burma (M73218_HEV-1_Burma) using blastp. Using the principle of parsimony, we defined antigenic regions as those with overlapping results coverage. Using the MEGA software, it was performed alignment of the epitopes of each antigenic region with human and swine HEV-3 and HEV-4 reference genomes (M73218_HEV-1_Burma, AP003430_HEV-3_JPN, AF082843_sHEV-3_JPN, AB197673_HEV-4_CHN, AJ272108_HEV-4_CHN, DQ279091_sHEV-4_CHN).

Resultados e Conclusão

A total of 15 and 176 linear B-cell epitopes were predicted in ORF1 and ORF2, respectively. Mapping coverage for ORF1 was only 4%, while for ORF2 it was 97%. When we look at the depth (number of epitopes mapped in the same region), ORF1 also showed lower results (max. 3) than ORF2 (max. 23). Four antigenic regions were in ORF1 and at least eight in ORF2, with two parsimonious regions. These regions had very different characteristics, one was in a variable region and the other in a conserved region of the ORF2. The variable epitopes for human and swine HEV-3 and HEV-4 genotypes may be useful to discriminate HEV infections more specifically. On the other hand, epitopes from conserved regions may be useful to identify different HEV infections with greater sensitivity. The low coverage and depth of predicted epitopes in ORF1 may indicate that this protein is poorly antigenic. There are at least two parsimonious antigenic regions for the synthesis of linear B-cell epitopes in ORF2 for the development of a serological assay for the diagnosis of HEV in humans and swine.

Palavras-chave

Hepatitis E virus (HEV), validation, serology, antibody, linear B-cell epitopes, swine.

Agradecimentos

CNPq