RESUMO
A method for attenuation of Leishmania species by culturing in vitro under gentamicin pressure has been used successfully with Leishmania mexicana, L. major, L. infantum, and L. donovani. The attenuated lines invaded but were unable to survive within bone marrow-derived macrophages in vitro, whereas wild-type parasites survived and multiplied. The attenuated lines of L. mexicana and L. major both failed to induce cutaneous lesions in the majority of BALB/c mice over a minimum 12-week observation period after subcutaneous injection of stationary phase parasites. The attenuated line of L. mexicana retained its properties in gentamicin-free medium over 40 subcultures. The attenuated lines of L. mexicana and L. major both induced significant protection in mice against challenge with wild-type parasites.
Assuntos
Leishmania major/imunologia , Leishmania mexicana/imunologia , Vacinas Protozoárias/imunologia , Vacinas Atenuadas/imunologia , Animais , Células da Medula Óssea/imunologia , Células da Medula Óssea/parasitologia , Meios de Cultura/química , Feminino , Gentamicinas/farmacologia , Leishmania donovani/patogenicidade , Leishmania infantum/patogenicidade , Leishmania major/patogenicidade , Leishmania mexicana/patogenicidade , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/patologia , Macrófagos/imunologia , Macrófagos/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Pele/patologia , Fatores de Tempo , VacinaçãoRESUMO
An attenuated line of Leishmania mexicana (the L. mexicana H-line) has been established by culturing in vitro under gentamicin pressure. BALB/c mice infected with the L. mexicana H-line developed a CD4(+)Th1-like response, indicated by the cytokine profile of their splenocytes stimulated by L. mexicana wild-type (WT) promastigotes. This profile is sustained after these mice are challenged with L. mexicana WT. Control mice infected with L. mexicana WT alone developed a CD4(+)Th2-like cytokine profile. In mice immunized with L. mexicana H-line and then challenged with WT-line, were eliminated when immunizing H-line parasites persisted in the skin and draining popliteal lymph nodes (PLNs). In experiments in which mice were inoculated with attenuated and WT parasites at the same time, either at the same site or on separate sides of the mouse, growth of the WT parasites was significantly contained and controlled, indicating a possible therapeutic role for the attenuated parasites.