A DIAGNOSTIC ELISA FOR VISCERAL LEISHMANIASIS, BASED ON ANTIGEN FROM MEDIA CONDITIONED BY LEISHMANIA-DONOVANI PROMASTIGOTES

Leishmania donovani promastigotes were cultured in a protein-free medi um for 3-5 days and the spent medium used to prepare antibody-detectio n ELISA plates. When the plates were used to test 29 Kenyan and 16 Nep alese patients with visceral leishmaniasis (VL; kala-azar), all the se ra collected at diagnosis were found to have high levels of parasite-s pecific IgG. The levels of these antibodies dropped 6-12 months post-i nitiation of antileishmanial therapy in all but one of the patients. A lthough the levels in sera from 59% of the treated patients fell to th ose measured in sera from healthy controls, those in sera from 17% of the patients did not drop below those seen at diagnosis. The antigen u sed did not cross-react with sera from patients with parasitological d iagnosis of malaria, filariasis, African trypanosomiasis or echinococc osis. Antibodies to antigens in the spent medium were detected, by wes tern blot, in all the sera from Nepalese patients with VL. Promastigot e-conditioned media could be the source of cheap antigen for the immun odiagnosis of leishmaniasis.