Serodiagnosis of leishmaniasis with recombinant ORFF antigen

The serodiagnostic potential of recombinant ORFF protein (rORFF) from Leish mania infantum was assessed by ELISA. Of 49 sera from confirmed cases of vi sceral leishmaniasis (VL), all were seropositive using 5 ng of rORFF and se rum diluted 1:20, while only 38 were positive with 500 ng of soluble antige n (SA) and 44 were positive by a direct agglutination test. There was also a positive correlation between spleen size and level of seropositivity with rORFF or SA. The reciprocal endpoint titer with rORFF was 1,280 for sera f rom VL patients, but < 20 with sera from malaria, filariasis, and tuberculo sis patients, as well as with sera from healthy individuals from endemic an d non-endemic areas. Sera from 10 confirmed cutaneous leishmaniasis cases f rom Turkey were negative or only weakly positive with rORFF, although 9 wer e positive with SA. Thus, rORFF protein appears useful as a sensitive reage nt for the differential diagnosis of VL caused by the Leishmania donovani a ni complex.