A CLONED ANTIGEN (RECOMBINANT K-39) OF LEISHMANIA-CHAGASI DIAGNOSTIC FOR VISCERAL LEISHMANIASIS IN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 PATIENTS AND A PROGNOSTIC INDICATOR FOR MONITORING PATIENTS UNDERGOING DRUG-THERAPY

Serologic assays using crude antigens for the diagnosis of visceral le ishmaniasis in human immunodeficiency virus type 1 (HIV)-seropositive patients have been shown to lack sensitivity and specificity, particul arly in AIDS patients. Antibodies to a cloned antigen, recombinant (r) K39, of Leishmania chagasi are specific for members of the Leishmania donovani complex and have been shown to indicate active disease in im munocompetent persons. This study demonstrated that antibodies to rK39 were also detectable in HIV-seropositive patients coinfected with Lei shmania infantum. Furthermore, the rK39 ELISA was more sensitive than an IFA for detecting L. infantum infections in patients with AIDS. In addition, antibody titers to rK39 in HIV-negative patients infected wi th L. infantum or L, chagasi declined during treatment with meglumine antimoniate or liposomal amphotericin B. In contrast, most patients wh o clinically relapsed showed increased antibody titers to rK39. These data demonstrate the diagnostic and prognostic utility of rK39 in dete cting active visceral leishmaniasis.