Distinct effects of HIV protease inhibitors and ERAD inhibitors on zygote to ookinete transition of the malaria parasite.

In an effort to eradicate malaria, new interventions are proposed to include compound/vaccine development against pre-erythrocytic, erythrocytic and mosquito stages of Plasmodium. Drug repurposing might be an alternative approach to new antimalarials reducing the cost and the time required for drug development. Previous in vitro studies have examined the effects of protease inhibitors on different stages of the Plasmodium parasite, although the clinical relevance of this remains unclear. In this study we tested the putative effect of three HIV protease inhibitors, two general aspartyl protease inhibitors and three AAA-p97 ATPase inhibitors on the zygote to ookinete transition of the Plasmodium parasite. Apart from the two general aspartyl inhibitors, all other compounds had a profound effect on the development of the parasites. HIVPIs inhibited zygote to ookinete conversion by 75%-90%, while the three AAA-p97 ATPase inhibitors blocked conversion by 50%-90% at similar concentrations, while electron microscopy highlighted nuclear and structural abnormalities. Our results highlight a potential of HIV protease inhibitors and p97 inhibitors as transmission blocking agents for the eradication of malaria.