Abstract text
Reliable and field suitable sero-diagnosis of visceral Leishmaniasis (VL) in East Africa is till today a big challenge due to low sensitivity and crossreactivity with other pathogens. To improve VL sero-diagnosis, new and field suitable POC tests were developed on the basis of a recombinant kinesin antigen from L. infantum (rKLi8.3). The new rkLi8.3 based sero-diagnostic devices revealed improved sensitivity and no cross-reactivity when tested with sera from patients originating from Sudan, India and South America, suffering from VL, malaria, tuberculosis and trypanosomiasis. We could show that rKLi8.3 based ELISA and LFT offer substantially increased diagnostic efficiency for VL in East Africa and other endemic areas, compared to currently commercial available sero-diagnostic tests.
Besides diagnosis, the current treatment of visceral leishmaniasis is also far from optimal, as many drugs induce resistent Leishmania strains and have severe side effects. It has been shown that the family of kinetoplastida (T. brucei, T. cruzi and Leishmania spp.) are highly susceptible to the proteasome inhibitor, GNF-6702. Characteristic sequence variations within the proteasome beta 4 and beta 5 subunits of kinetoplastida have been made responsible for the specific binding of GNF-6702 to the proteasome of kinetoplastia but not humans. To test whether these proteasome subunits are conserved throughout various Leishmania isolates and differ from the human proteasome, we analyzed the beta 4 and beta 5 proteasome subunits of 15 different Leishmania strains and found conserved AA substitutions in the beta 4 proteasome subunit of all strains analayzed, indicating that GNF-6702 is a potential drug for VL. Further, analyzing the parasite survival by treating pro-and amastigote L. donovani with inhibitors for constitutive - (GNF-6702) or immuno-proteasomes (ONX-0914) revealed that ONX-0914 had no effect on promastigote parasites but strong effects on amastigotes. This finding strongly suggests that the pressure of the intracellular lifestyle alters the proteasome composition from a constitutive to an immuno-like form. We are currently characterizing the proteasome subunit composition of pro-and amastigote Leishmania.