Efficacy of the vaccination of C57BL/6 mice against infection with different species of Leishmania

Antigens were isolated from lysates of promastigotes of Leishmania infantum by electro-elution from polyacrylamide gels. Antigens with respective molecular weights for F2 = 94-67 kd; F5 = 30-20 kd and F6 below 20 kd, were injected intravenously in C 57 BL/6 mice. The immune sera were studied by indirect immunofluorescence; an in vivo test showed their inhibitory effect on the life cycle of several Leishmania species from the Old and the New world. Furthermore, mice immunized with F2, F5 or F6 were protected against an infection by Leishmania major. These results demonstrate that vaccination is efficient in mice differing genetically for either susceptibility (BALB/c) or partial resistance (C 57 BL/6) to Leishmania infections. Recently, we reported that a single monoclonal antibody raised against Leishmania infantum can prevent the development of Leishmania major and Leishmania mexicana amazonensis. Indeed, BALB/c mice injected subcutaneously with promastigotes pre-treated with this monoclonal antibody, did not present any cutaneous lesions over a period of 3 months. Using a mouse in vivo model--intraperitoneal injection of TG 180 mouse sarcoma cells along with monoclonal antibody pre-treated promastigotes--such an antibody-mediated inhibition was also observed against Old and New World Leishmania species. Protective monoclonal antibodies recognized by immunoblotting technique three antigenic fractions (40, 70 and 113 kd) common to several Leishmania species. Antigenic preparations from Leishmania infantum extracts were isolated by electro-elution from polyacrylamide gels.(ABSTRACT TRUNCATED AT 250 WORDS)