Innate immune responses against malaria pattern molecules in the mosquito vector

We have focused our interest on the similarities between the human host and the mosquito vector in their innate immune responses against human malaria parasite Plasmodium falciparum. Several basic innate immune molecules and mechanisms are similar in insects and humans. Since the parasite has adjusted to handling the immune system of its mosquito vector Anopheles gambiae and its human host, some mechanisms by which the parasite circumvents the innate immune systems are likely to be used in both of its hosts. During an immune challenge, the innate immune system responds to different pattern molecules associated with the intruder. There are non-peptide molecules, ie two isoprenoid precursor molecules IPP and HMBPP known to be recognized by human gdT-cells and cause their rapid proliferation and subsequent cytolytic activity towards P. falciparum. We investigate the effect of HMBPP adding it to blood and feeding it to mosquitoes.  We found that mosquitoes respond by producing antioxidant proteins in addition to several known antimicrobial peptides. Recently, we used whole transcriptome sequence analyses in a temporal study after such a feed and revealed and interesting and unexpected picture of genes regulated by this molecule. We will use RNAi knock down or CRISPRCas9 system to functionally assess the importance of what we see as key genes and pathways regulated by HMBPP and determine how they may affect P. falciparum infectiousness. In addition we have looked at the effects of this compound on fecundity, feeding behavior, survival. This has changed our understanding of how important the parasite molecular manipulations of the host and vector are for its transmission.

Key words: innate immunity, Isopentenyl pyrohophate (IPP), (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), Plasmodium falciparum, transcriptome analyses, CRISPRCas9