Immunogenicity and safety of autoclaved Leishmania major plus BCG vaccine in healthy Sudanese volunteers

In a longitudinal study in the epidemiology of Leishmania donovani infectio n in an endemic focus in eastern Sudan, we observed that previous exposure or infection with Leishmania major appeared to protect against visceral lei shmaniasis caused by L. donovani. We therefore conducted a study to test th e safety and immunogenicity of a vaccine consisting of autoclaved L. major (ALM) plus BCG in inducing protection in vaccinated individuals. Leishmania -negative healthy Sudanese volunteers were enrolled in the study and were d ivided into three groups: group (A) received ALM + BCG, group (B) received BCG alone, and group (C) received the vaccine diluent. The subjects were ex amined for their clinical and immunological responses before intervention, following intervention and 6-8 weeks after vaccination. Vaccinated subjects (group A) developed localized reactions at the sites of vaccine inoculatio n that ulcerated and healed within 4-6 weeks; 61.6% of them converted to le ishmanin reactive following vaccination. Only one subject in group (C) beca me leishmanin-positive. A total 76.9% of the vaccinated volunteers in group (A) produced significant levels of interferon-gamma in response to L. majo r antigen. The vaccine produced significant cellular immune responses that may protect against natural challenge. None of the groups had systemic reac tions and all the reactions observed in the vaccinated group were comparabl e with the BCG-vaccinated group. (C) 2001 Elsevier Science Ltd. All rights reserved.