Type-I Interferons drive cell-autonomous immunity to malaria

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PROJECT SUMMARY Malaria, caused by the protozoan Plasmodium is a devastating disease that kills close to half a million people each year. Plasmodium transmitted by mosquitoes undergo asymptomatic development and replication in the liver, before transitioning into infecting the red blood cells and causing the deadly clinical disease. Therefore, hindering Plasmodium infection in the liver has been pursued as a strategy to delay, reduce the severity of, or prevent clinical malaria. Although natural immune responses are known to control Plasmodium infection in the liver, we understand very little about the mechanisms that underlie this process. This has prevented us from harnessing the innate immune pathways in the liver to develop immunological or therapeutic approaches to impede or eliminate Plasmodium infection in its liver-stage. Our group's long-term goal is to understand the innate immune mechanisms that control Plasmodium in the liver. The objective of this application is to deter- mine how type-1 interferons (IFNs) facilitate the elimination of Plasmodium from its host hepatocytes. Our central hypothesis is that type-1 IFN signaling in the hepatocytes would enable the destruction of the para- sitophorous vacuolar membrane (PVM), as well as the Plasmodium contained in it through `non-canonical au- tophagy'. We propose to determine the mechanisms by which type-1 IFNs recruit the autophagy protein LC3 to facilitate the destruction of Plasmodium contained within the parasitophorous vacuole through lysosomal degradation in Specific Aim 1, and how type-1 IFNs enable a class of interferon induced GTPases, called guanylate binding proteins to cause mechano-enzymatic degradation of the PVM itself, to initiate a pathway of programmed cell-death in the infected hepatocytes in Specific Aim 2. Type-1 IFNs are known to induce multiple genes and pathways in various cell types. The rationale for the proposed research is that, by determining the specific molecular mediators of type-1 IFN signaling pathway that enable the elimination of Plasmodium in hepatocytes, we will have identified new, and specific therapeutic opportunities to better control or eliminate Plasmodium in the liver. This knowledge will be applicable for the development of new immunoprophylactic antimalarial drugs for travelers, or mass drug administration in malaria endemic areas. Such therapies can also potentially clear dormant Plasmodium infections in the liver, or help improve live-attenuated anti-malarial vac- cine candidates targeting the liver-stage of malaria. Our proposed research will employ a series of innovative tools such as Cre-recombinase expressing Plasmodium capable of ablating specific host genes in only the infected hepatocytes, and reporter hepatocytes that distinguish the lysis of Plasmodium from that of its PVM. In addition to taking us a step closer to the control and possible eradication of malaria, at a fundamental level, the completion of this proposal will foster the expansion of our knowledge pertinent to the improvement of human health, advancing the core mission of the NIH.