In vitro Activity of Bacillus thuringiensis (H14) 43 kDa Crystal Protein Against Leishmania major

Abstract

Leishmaniases are caused by hemoflagellate protozoan which belongs to genus Leishmania order Kinetoplastida, family Trypanosomatidae, that infect vertebrate hosts through the bites of sand fly female Phlebotomus spp. Antimonials are still considered as the drug of choice for the treatment of leishmaniases. However, using microbial biological control agents as alternative strategy was developed. Bacillus thuringiensis (B.t.) crystal proteins are one of choice in this study. Bacillus thuringiensis is an endospore-forming, Gram-positive, soil bacterium that produces crystalline, proteinaceous inclusions, toxic mainly to lepidopteran, coleopteran and dipteran insects. The aim of this study is to investigate the effect of active non truncated core toxin of B.t. serovar thuringiensis (H14) 43 kDa for their activity against Leishmania major promastigotes. Bt serovar. thuringiensis separated crystalline proteins were dissolved, fractionated and the untruncated protein core was purified. The dissolved purified active protein fraction was examined electrophoretically by 7.5% native gel and 12% SDS-PAGE and its molecular weight was found to be 43 kDa. This active protein fraction was bioassayed against L. major promastigotes suspension (7×10 promastigotes ml ) in final concentrations ranging from 100 - 0.78 µg ml aseptically in 7 1 1 replicates. The bioassay of protein fraction against L. major promastigotes showed that its LC is 4.95 µg ml . 50 1 The cytopathological examination of the treated promastigotes revealed that the pathological changes passed through degenerative changes that started with shortening, swelling and ended with complete death. Our results point to Bt (H14) 43 kDa crystal protein as a potential candidate for further investigation and potential application as a therapeutic agent against Leishmaniases.