Experimental mixed infection ofLeishmania(Leishmania)amazonensisandLeishmania(L.)infantumin hamsters (Mesocricetus auratus)

Abstract

SUMMARYIn South America, visceral leishmaniasis is frequently caused byLeishmania infantumand, at an unknown frequency, byLeishmania amazonensis. Therefore, mixed infections with these organisms are possible. Mixed infections might affect the clinical course, immune response, diagnosis, treatment and epidemiology of the disease. Here we describe the clinical course of mixed infections withL. amazonensisandL. infantumin a hamster model. We show that mixed infections are associated with more severe clinical disease than infection withL. amazonensisorL. infantumalone. In spleens with mixed infections,L. infantumoutcompetedL. amazonensisin the tissue, but not in culture from tissue. We found increased levels of IgG in animals infected withL. infantum.Although more than 30 bands were revealed in a Western blot, the highest immunogenicity was observed with proteins having molecular masses of 95 and 90 kDa, whereas proteins with molecular masses of lower than 50 kDa were reactive frequently with serum from hamsters infected withL. amazonensis, and proteins with molecular masses of 80 and 70 kDa were reactive only with serum from hamsters infected withL. infantum. This finding has important implications regarding the biology ofLeishmaniaand humoral immune responses to infections with these organisms.