Delayed-type hypersensitivity to a recombinant mycobacterial antigen, MPB64, in guinea pigs sensitized to <i>Mycobacterium tuberculosis</i> or <i>Mycobacterium bovis</i> BCG

Abstract

Recombinant MPB64 (rMPB64), a mycobacterial antigen, was obtained from an Escherichia coli clone transformed with a recombinant expression vector, pMAL64c. The rMPB64 was examined for the activity to elicit delayed-type hypersensitivity (DTH) in guinea pigs injected with liver Mycobacterium tuberculosis H37Rv or live M. bovis BCG Tokyo. It was found that rMPB64 has the same reactivity as native MPB64 (nMPB64) or MPT64 (nMPT64) and the potency to elicit DTH was 13.4 times higher than that of PPD. Because MPB64 is secreted only by living M. tuberculosis and some strains of BCG, it is possible to use this antigen for the diagnosis of tuberculosis.