DELAYED-TYPE HYPERSENSITIVITY TO A RECOMBINANT MYCOBACTERIAL ANTIGEN,MPB64, IN GUINEA-PIGS SENSITIZED TO MYCOBACTERIUM-TUBERCULOSIS OR MYCOBACTERIUM-BOVIS BCG

Recombinant MPB64 (rMPB64), a mycobacterial antigen, was obtained from an Escherichia coil clone transformed with a recombinant expression v ector, pMAL64c. The rMPB64 was examined for the activity to elicit del ayed-type hypersensitivity (DTH) in guinea pigs injected with live Myc obacterium tuberculosis H37Rv or live M. bovis BCG Tokyo. It was found that rMPB64: has the same reactivity as native MPB64 (nMPB64) or MPT6 4 (nMPT64) and the potency to elicit DTH was 13.4 times higher than th at of PPD. Because MPB64 is secreted only by living M. tuberculosis an d some strains of BCG, it is possible to use this antigen for the diag nosis of tuberculosis.