USE OF IN-VIVO COMPLEMENTATION IN MYCOBACTERIUM-TUBERCULOSIS TO IDENTIFY A GENOMIC FRAGMENT ASSOCIATED WITH VIRULENCE

Novel molecular tools and genetic methods were developed to isolate ge nomic fragments of Mycobacterium tuberculosis that may be associated w ith virulence. We sought to restore virulence, a characteristic of M. tuberculosis that is correlated with growth rate in mouse spleen and l ung tissue, to the avirulent strain H37Ra by complementation. A repres entative library of the virulent M. tuberculosis strain H37Rv was cons tructed and transformed into H37Ra. Enrichment for individual faster-g rowing recombinants was achieved by passage of pools of H37Ra transfor mants harboring the H37Rv library through mice. A molecular strategy w as devised to isolate and clone the H37Rv genomic DNA fragment ivg, wh ich conferred a more rapid in vivo growth rate to H37Ra.