Memory formation is the most important aspect of a vaccine which can guarantee long-lasting immunity and protection. The main aim of the present study was to evaluate the memory immune responses after immunization with a mini vaccine. Mice were immunized with human immunodeficiency virus-1 P24-Nef fusion peptide and then cellular and humoral immune responses were evaluated. In order to determine long-lived memory, immune responses were monitored for 20 weeks after final immunization. The results showed that the candidate vaccine induced proliferation and cytotoxic T lymphocyte responses and shifted cytokine patterns to T helper-1 profile. Evaluation of humoral immune responses also showed an increase in total peptide specific-IgG titer and a shift to IgG2a humoral response. Monitoring of immune responses at weeks 4, 12 and 20 after last immunization showed that immunologic parameters have been sustained for 20 weeks. Our findings support the notion that long-lived memory responses were achieved using a mini vaccine immunization.
