The focus of this project continues to be on properties of leishmanial parasites isolated from patients and the immune response of the infected human host. Conventional parasitological techniques are used, and immune response of the host is assessed by cell-mediated immune responses such as lymphocyte proliferation, generation of lymphokines (IL-2 and Gamma-interferon) and delayed hypersensitivity skin test. Parasite isolates from cutaneous cases originating in Surinam were obtained, as well as isolates from visceral infections in India. Several of the latter isolates were from patients who failed to respond to Pentostam and Pentamidine therapy. A new patient with diffuse cutaneous leishmaniasis (DCL) from Mexico was studied. He apparently recovered cellular immune responsiveness while receiving intensive antimony therapy. Pathogenicity of leishmanial isolates, as well as the sequence in pathologic events during infection in the ear of BALB/c mice, is also being studied. A phase I trial of safety and immunogenicity of a P. falciparum anti-sporozoite vaccine is in progress in collaboration with the Walter Reed Army Institute of Research (WRAIR). The vaccine is a recombinant protein (R32 tet 32), produced in E. coli and absorbed with alum. Fifteen human volunteers have received 10 to 800 Mug doses at monthly intervals. One recipient had an allergic reaction after the third dose. Humeral antibody responses were low with no booster effect and cell-mediated responses are still being evaluated.
