Enhancement of Leishmania amazonensis infection in BCG non-responder mice by BCG-antigen specific vaccine.

Different patterns of cutaneous leishmaniasis can be induced when a challenge of alike dose of Leishmania amazonensis amastigotes in various inbred strains was applied. Two strains of mice, the Balb/c and C57BL/10J, showed exceptional susceptibility, and 10(6) amastigotes infective dose lead, to ulcerative progressive lesions with cutaneous metastasis and loss by necrosis of leg on which the footpad primary lesion occurred. Lesions were also progressive but in a lower degree when C3H/HeN and C57BL/6 were infected. Lesions progress slowly in DBA/2 mice presenting lesions which reach a discreet peak after 12 weeks, do not heal but do not ulcerate. DBA/2 mice is, therefore, a good model for immunomodulation. In attempt to determine the influence of BCG in vaccination schedule using microsomal fraction, DBA/2 became an excellent model, since it is also a non-responder to BCG. Vaccination of DBA/2 mice, receiving the same 10(6) BCG viable dose and 10 micrograms or 50 micrograms of protein content of microsomal fraction, lead to a progressive disease with time course similar to those observed in susceptible non-vaccinated C57BL/10J mice after 6 months of observation. An enhancement of infection in BCG non-responder mice suggests that use of BCG as immunostimulant in humans could be critical for both vaccination and immunoprophylactic strategies.