Difference in TB10.4 T-cell epitope recognition following immunization with recombinant TB10.4, BCG or infection with Mycobacterium tuberculosis.

Most novel vaccines against infectious diseases are based on recombinant Ag; however, only few studies have compared Ag-specific immune responses induced by natural infection with that induced by the same Ag in a recombinant form. Here, we studied the epitope recognition pattern of the tuberculosis vaccine Ag, TB10.4, in a recombinant form, or when expressed by the pathogen Mycobacterium tuberculosis (M.tb), or by the current anti-tuberculosis vaccine, Mycobacterium bovis BCG. We showed that BCG and M.tb induced a similar CD4+ T-cell specific TB10.4 epitope-pattern, which differed completely from that induced by recombinant TB10.4. This difference was not due to post-translational modifications of TB10.4 or because TB10.4 is secreted from BCG and M.tb as a complex with Rv0287. In addition, BCG and TB10.4/CAF01 were both taken up by DC and macrophages in vivo, and in vitro uptake experiments revealed that both TB10.4 and BCG were transported to Lamp+-compartments. BCG and TB10.4 however, were directed to different types of Lamp+-compartments in the same APC, which may lead to different epitope recognition patterns. In conclusion, we show that different vectors can induce completely different recognition of the same protein.