Evaluation of Leishmania antigens for the diagnosis of visceral leishmaniasis

Abstract

In this study the liquid direct agglutination test (LQ-DAT), freeze dried direct agglutination test (FD-DAT) -using serum and filter paper samples, rK39 dipstick test (using two different kits) and KATEX test were evaluated for the diagnosis of visceral leishmaniasis (VL) in Sudan. The Sensitivity and specificity of all tests were determined compared with microscopic demonstration of the parasite in lymph node (LN), bone marrow (BM), and spleen aspirates. The sensitivity and specificity of the evaluated tests were as follows; LQ-DAT(87.1%) and (77.7%), FD-DAT using serum samples (88.7%) and (73.6%), FD-DAT using filter paper samples (87.1%) and (78.5%), rK39 In-Bios dipsticks (74.2%) and (76.0%), rK39 Dia-Med(88.7%) and (75.2%), and KATEX test (87.1%) and (85.1%). Combination of two serological tests in relation with clinical, epidemiological and other diagnostic data can be a valuable tool for diagnosis of VL. KATEX test is a simple, rapid, non invasive, sensitive and specific test more than other used. Therefore it is suitable for diagnosis of VL in combination with DAT test. In this study the electrophoretic protein profiles of promastigote extract of L.donovani, L.infantum, L.archibaldi and L.major isolates were studied using SDS-PAGE and western blot technique, they all showed several identical bands, with molecular weights ranging from 29-116kDa,the most prevalent bands ranged from 45-66kDa. Sera from VL patients showed reaction with antigens ranging between 29-116 kDa. Leishmania proteins were also detected in urine of VL patients using SDS-PAGE. in the urine of each VL patient three common protein bands ranged from 29-66 kDa were found ,they were absent in the urine of all non-endemic control group but they were found in urine of some controls living in the endemic area. These bands were undetectable in the urine after completion of pentostam treatment in some patients. Two of these proteins were reactive with sera of confirmed VL patients confirming their antigenic properties