MERCURY RESISTANCE AS A SELECTIVE MARKER FOR RECOMBINANT MYCOBACTERIA

The use of antibiotic-resistance markers for the selection of recombin ant mycobacteria is widespread but questionable considering the develo pment of live recombinant BCG vaccines. In contrast, vector-encoded re sistance to heavy metals such as mercury may represent an interesting alternative for the development of live vaccines compatible with use i n humans and in animals. The mercury resistance genes (mer) from Pseud omonas aeruginosa and from Serratia marcescens were cloned into the Es cherichia coli-nnycobacterium shuttle vector pRR3, The resulting vecto rs, designated pMR001 and pVN2, were introduced by electroporation int o Mycobacterium smegmatis, Mycobacterium bovis BCC and Mycobacterium t uberculosis. The recombinant mycobacteria were stable in vitro and in vivo, and had high-level mercury resistance, thus indicating that the mer genes can be useful as selective markers in mycobacteria.