Human genetic variation associates with infection by derived Ugandan M. tuberculosis lineage

Several studies have examined host and pathogen genetic influences on tuberculosis (TB) susceptibility separately, but relatively few studied their combined effects. However, host-pathogen interactions or co-evolution may explain the inability to replicate many reported human genetic effects across global populations and provide additional insight into TB risk. In this study, we address such possible interactions by focusing on the outcome of infection with the L4-Uganda M. tuberculosis sub-lineage and human genetic variants as independent variables. This is possible because the L4-Uganda sub-lineage is both restricted to Uganda and nearby locations and is recent there, compared to other more ancestral L4 lineages.

Our study consisted of 276 culture-confirmed adult TB cases from a long-standing household contact study. We conducted a genome-wide association study, with infection with L4-Uganda versus L4-NonUganda as the outcome.

Multiple loci with results suggestive of association (p<10-5) also demonstrated convergent relevant evidence for strain specific infection via: evidence of gene expression in relevant cells and lung tissue, signatures of natural selection, eQTL expression, and CRISPR screens for immunity-related genes. We also replicated previously published host-pathogen interaction effects, demonstrating that effects seen for other sub-lineages were also present for L4-Uganda.

These results provide evidence for host-pathogen co-evolution in TB, consistent with our previous work, and indicate these interactions involve genes highly relevant to the host immune response to Mycobacterium infection.