Session 51Poster Presentations Novel Vaccine Approaches Session Day and Time: Thursday 1:30 - 3:30 pm Room: Hall D
434 Parasitic Infection Alters the Quality of the Immune Response to HIV-1 Vaccines J. D. Boyer*1, T. Robinson1, D. Artis1, D. B. Weiner2, P. Scott2 1Univ of Pennsylvania, Philadelphia and 2Veterinary Sch, Univ of Pennsylvania, Philadelphia, PA
Background: More than 95% of all HIV-infected people now live in the Developing World, and 95% of all deaths have occurred among its people. In these countries, chronic parasitic infection adds another level of complexity to AIDS vaccine development. Helminthic and protozoan infections are common in developing countries. Approximately 1.5 billion people carry a parasitic burden. These persons are in a constant state of immune activation with a dominant Th2 type of cytokine profile, high IgE levels, and eosinophilia. Such an immune profile may have an adverse impact on the efficacy of HIV-1 vaccines.
Methods: We have studied the impact of parasitic infection on the vaccine induced cellular immune response. Balb/c mice were infected with L. major. A Th2 immune profile was observed 2 wks post-parasitic infection. Following the establishment of chronic parasitic infection, the mice were immunized with a DNA HIV-1 vaccine. The level of vaccine-induced CD8 and CD4 responses were assessed.
Results: We observed that the number of CD8 lymphocytes able to IFN-gamma following stimulation with HIV-1 antigen decreased from approximately 200 to 20 CD8 lymphocytes. Yet, we observed a slight increase in the number of HIV-1 antigen specific CD4 lymphocytes secreting INF-gamma in the parasitically infected mice as compared to the uninfected and HIV-1 DNA vaccinated mice. Therefore, in subjects chronically infected with parasites it may be beneficial to enhance a vaccine induced cellular immune response by co-injecting DNA plasmids that code for cytokines that enhance the CD8 immune response. We have observed that the CD8 antigen specific cellular response to the HIV-1 DNA vaccine was significantly enhanced by the addition of IL-15 independently of CD4 T-cell expansion.
Conclusions: These data indicate that IL-15 could be particularly valuable in developing countries where many individuals have an immune profile that is dominated by a Th2 cytokine profile caused by chronic parasitic infection.
