Analysis of the humoral immune response against total and recombinant antigens of Leishmania infantum: correlation with disease progression in canineexperimental leishmaniasis

Leishmaniasis by Leishmania infantum in the Mediterranean Basin constitutes an important problem in both human and veterinary medicine. Based in both the importance of canids as reservoirs for the human disease and the fact t hat the canine disease may be an excellent model for the human condition, t he present work has been conducted to analyze clinical and immune mechanism s associated with canine experimental leishmaniasis. Six-month-old mixed-br eed dogs were intravenously infected with L. infantum promastigotes and the infection course was monitored along a 343 days-period. On day 75 post-inf ection (p.i.), amastigotes were observed in the lymph nodes of all dogs. Th e analysis of the humoral response against total L. infantum antigens by bo th ELISA and Western blotting evidenced a correlation between the levels of IgG isotypes (IgG1 and IgG2) and disease progression. It was observed that in those animals showing either a regressive or an oligosymptomatic form o f the disease, the anti-Leishmania IgG1 antibodies were undetectable wherea s those animals developing active disease showed high levels of anti-Leishm ania IgG1 antibodies. Additionally, the time-course of antibody production against L. infantum recombinant antigens in the experimentally infected dog s has been analyzed. The present data suggest that reactivity against the h eat-shock protein 70 (HSP70) may be used as diagnostic marker of early step s of infection, and that the appearance of anti-histone antibodies is assoc iated with progression of infection to disease status. (C) 1999 Elsevier Sc ience B.V. All rights reserved.