Exploitation of parasite-derived antigen in therapeutic success against canine visceral leishmaniosis. Veterinary Group of Lupino.

In an attempt to obtain therapeutic success against canine visceral leishmaniosis, the potential of LiF2 antigen (Leishmania infantum-derived Fraction 2, 94-67 kDa), given alone or in combination with the chemotherapeutic agent N-methylglucamine antimonate, was compared with conventional chemotherapy with that drug. Absence of any parasite in direct microscopic examination of bone-marrow aspirates in treated dogs was considered a parasitological cure, i.e. therapeutic success. Results showed that the disappearance of clinical symptoms did not always indicate parasitological healing in dogs. The parasitological healing rates with chemotherapy and immunotherapy alone were 37.5% and 25% respectively, in contrast to the 100% cure rate observed with chemotherapy combined with immunotherapy. The development of a protective response in dogs, as measured by the in vitro leishmanicidal activity of monocyte-derived macrophages in the presence of autologous lymphocytes, was found to correlate well with the success of therapy. The overall findings of this study give an important insight into the immunotherapeutic strategy by which therapeutic success can be achieved in canine visceral leishmaniosis.