Identification and Characterization of a Loss-of-Function Human MPYS Variant

MPYS, also known as STING and MITA, is an IFNβ stimulator essential for host defense against RNA, DNA viruses and intracellular bacteria. MPYS also facilitates the adjuvant activity of DNA vaccines. Here we report identification of a distinct human MPYS haplotype that contains three non-synonymous SNPs, R71H-G230A-R293Q (thus named the HAQ haplotype). We estimate, in two cohorts (1074 individuals), that ~3% of Americans are homozygous for this HAQ haplotype. HAQ MPYS exhibits a >90% loss in the ability to stimulate IFNβ production. Furthermore, fibroblasts and macrophage cells expressing HAQ are defective in Listeria monocytogenes infection-induced IFNβ production. Lastly, we find that the loss of IFNβ activity is due primarily to the R71H and R293Q SNPs in HAQ. We hypothesize that individuals carrying HAQ may exhibit heightened susceptibility to viral infection and respond poorly to DNA vaccines.