DUPLICATION OF GENES ENCODING THE IMMUNODOMINANT 38 KDA ANTIGEN IN MYCOBACTERIUM-INTRACELLULARE

Mycobacterium avium is a causative agent of mycobacterioses in systemi cally immunocompromised individuals, whereas Mycobacterium intracellul are is responsible for causing infections in relatively immunocompeten t hosts. In an attempt to identify components that could be involved i n virulence, we characterised the 38 kDa-encoding gene of M. intracell ulare that is absent in M. avium. This antigen cross-reacts immunologi cally with a major 38 kDa antigen of M. tuberculosis, and both antigen s are homologues of the phosphate transport subunit S (PstS) of the ps t complex of Escherichia coli. Unlike the M. tuberculosis complex the M. intracellulare coding gene was found to be duplicated. We also iden tified and characterised other pst genes that may constitute an operon . Considering that multiple isoforms of PstS are present in mycobacter ia the possible role of pstS1 genes for pathogenesis is discussed.