MARCH1 regulates anti-malarial immunity through interferon signaling and T cell activation

Malaria infection induces complex and diverse immune responses, including impairment of dendritic cell (DC) function and immune suppression that may contribute to the low vaccination antibody titers to some antigens in endemic populations. To elucidate the mechanisms underlying host-parasite interaction, we performed a genetic screen during early Plasmodium yoelii infection and identified a large number of interacting host and parasite genes/loci after trans-species expression quantitative trait loci (Ts-eQTL) analysis. We next investigated a host E3 ubiquitin ligase gene (march1) that was clustered with interferon stimulated genes. March1 can inhibit MAVS/STING induced IFN-I signaling and reverse inhibition of viral replication mediated by MAVS in vitro. However, in malaria-infected hosts, deficiency of march1 activates IFN signaling inhibitors such as SOCS1, SOCS3, and TRIM24, leading to reduced early (24h) serum IFN-I levels. Increased CD86+ DC populations and elevated levels of IFN-? and IL-10 produced by T cells day 4 post infection protect infected march1-/- mice. Malaria lysate stimulate MACRH1 expression, which reduces CD86+ DC cells and impairs T cell activation. This study reveals previous unknown functions of MARCH1 in innate response to malaria infections and provides potential avenues for activating anti-malaria immunity and enhancing vaccine efficacy. Whole spleen RNA from mice (strain C57BL/6, sourced from two different suppliers, or March1 Knockout) infected with malaria strains YM, N67, or N67C, harvested 24 hrs or 4 days post infection.