A novel CD4+ T-helper lymphocyte epitope in the VP3 protein of hepatitis A virus.

Prediction analysis of TH-cell epitopes in the VP3 capsid protein of the hepatitis A virus (HAV) revealed the occurrence of a putative TH epitope in the 102-121 region complying with all the algorithms tested. To confirm these predictions, spleen T lymphocytes obtained from BALB/c mice previously immunised with HAV, were stimulated in vitro with different concentrations of synthetic peptides 102-121 and 110-121 of VP3. The ability of these peptides to stimulate CD4+ T-helper lymphocytes proliferation was evaluated by an immunological flow cytometry detection of bromodeoxyuridine incorporation. Using this method, it is concluded that the amino terminal part of the VP3 102-121 sequence contains a T cell epitope.