Determinants of TB control, relapse and reinfection

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), continues to be a severe global health problem. TB is multifaceted, but a central clinical and microbiologic feature of the disease is the ability of Mtb to resist complete elimination, both by the host immune system and by chemotherapeutic agents with potent growth inhibitory activity. This persistence in the face of immunologic and antibiotic pressure underlies several important facets of TB disease, including 1) the existence of latent tuberculosis infection (LTBI) and, in the setting of immunologic failure of LTBI control, its role in the genesis of active TB and 2) the prolonged course of TB antibiotic therapy, which requires 6 months of multidrug therapy to achieve reliable clinical cure. Rather than producing complete bacterial eradication in all treated subjects, cure following TB chemotherapy is now understood to be an antibiotic induced paucibacillary state in which prevention of relapse depends in part on poorly understood host factors. The host and bacterial determinants that mediate these two interrelated types of persistence are only partially understood, a knowledge gap the Tri-I-TBRU aims to fill. We propose a set of 3 intersecting projects and 3 cores all focused on different facets of the problem of paucibacillary TB, both post treatment and LTBI. The projects will use samples and clinical data from TB cohorts at our clinical site at GHESKIO in Port Au Prince Haiti, to examine the immunologic, microbiomic, transcriptomic, pharmacokinetic, and genetic factors that influence or predict the transition points between paucibacillary states of TB disease and active transmissible infection. These human studies will be compared and contrasted with a new mouse model of paucibacillary infection that will allow us to test mechanistic hypotheses about the host and bacterial determinants of paucibacillary disease. This work with be conducted by a team of highly collaborative investigators who have who have worked well together for several years.