A potent antigen in animals immunized with live bacteria, it induces a strong delayed-type hypersensitivity (DTH) in immunized animals (PubMed:10531201). Elicits a mostly Th1 type of T-cell response in healthy humans; induces IFN-gamma production from CD4(+) and CD8(+) cells (PubMed:12654810). Functions as an adhesin, binds to mouse macrophages via mannose residues (PubMed:10531201, PubMed:25359607). Might interact via host CD209 (PubMed:16092920). Glycosylated, with mannose residues (PubMed:8626314, PubMed:10542234, PubMed:10531201, PubMed:25359607). The secreted protein has from 0 to 9 mannose residues, the majority have 6, 7, or 8 mannose residues (22, 24 and 17% respectively) (PubMed:10531201). Deglycosylated molecules had a significantly lower capacity to elicit a DTH reaction in guinea pigs in vivo or to activate specific T lymphocytes in vitro (PubMed:10531201). Pretreating mouse macrophages with mannan decreases binding of M.tuberculosis (PubMed:25359607). The non-glycosylated form stimulates IFN-gamma production however, so glycosylation is not essential (PubMed:12654810). Runs as 45 and 47 kDa protein, the nature of the difference between the 2 forms is not known but is still seen after alpha-mannosidase treatment (PubMed:10531201). Chemically or enzymatically deglycosylated protein. Major immunodominant antigen that has potential as a vaccine against tuberculosis (PubMed:10542234, PubMed:10531201, PubMed:12654810). Can be used as a DNA vaccine in guinea pigs (PubMed:12654810). Apa-ELISA could be used in diagnosis. Belongs to the Apa family. Was originally thought to be involved in molybdenum transport.