Epitope mapping of Mycobacterium tuberculosis proteins using a non-human primate model of infection

Abstract

Abstract Mycobacterium tuberculosis, the causative agent of tuberculosis, is the leading cause of death by a single infectious agent worldwide. Many studies have focused on the necessity of T cells in combating tuberculosis, particularly at the primary site of infection in the lungs, the granuloma. In spite of their importance in TB disease, very low frequencies of T cells in the granuloma produce cytokine. Our objective is to determine the number and function of Mtb specific T cells in tissues and the periphery using tetramers. We have developed non-human primate (NHP) models of Mtb infection which recapitulate human infection, however, both humans and many NHPs have high MHC variability making studies aimed at understanding the role of specific T cells at the site of infection difficult. For this study, we used a Mauritian cynomolgus macaque (MCM) model, due to their limited MHC variability, to map epitopes of Mtb proteins Rv1196 and Rv0125. Using homozygous animals we found that both proteins elicit peak peripheral IFNγ responses early post infection. We mapped epitopes using pooled or individual peptides in IFNγ Elispots and determined the peak binding regions. We tested allele restriction using RM3 cells expressing major M1 alleles. These data can be used to design tetramers which are vital in determining the number and functionality of antigen specific T cells in the periphery, LN, and lung granulomas of infected MCMs. Understanding the number and function of these Mtb specific T cells following infection will provide a deeper understanding of the role T cells play in pathology and bacterial containment.