Resumo

VERAS, PST et al. A dhfr-ts^- Leishmania major Knockout Mutant Cross-protects against Leishmania amazonensis . Mem. Inst. Oswaldo Cruz [online]. 1999, vol.94, n.4, pp. 491-496. ISSN 0074-0276.  http://dx.doi.org/10.1590/S0074-02761999000400011.

E10-5A3 is a dhfr-ts^- Leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent L. major infection in both genetically susceptible and resistant mice. We investigated the capacity of dhfr-ts^- to protect against heterologous infection by L. amazonensis. The degree of protection was evaluated by immunization of BALB/c or C57BL/6 mice with E10-5A3, followed by L. amazonensis challenge. Whether immunized by subcutaneous (SC) or intravenous (IV) inoculation, susceptible and resistant mice displayed a partial degree of protection against challenge with virulent L. amazonensis. SC-immunized BALB/c mice developed lesions 40 to 65% smaller than non immunized mice, while IV immunization led to protection ranging from 40 to 75% in four out of six experiments compared to non immunized animals. The resistant C57BL/6 mice displayed comparable degrees of protection, 57% by SC and 49% by IV immunization. Results are encouraging as it has been previously difficult to obtain protection by SC vaccination against Leishmania, the preferred route for human immunization.

Palavras-chave : auxotrophic Leishmania major; Leishmania amazonensis; immunization; cross; protection.