Figure 1.

Summary of proteome-wide screens for Mtb antigens. (A) Summary of screen for targets of CD4+ T cells (8). Mtb peptide sequences that represented 5 complete and 16 incomplete Mtb genomes were analyzed by HLA Class II consensus prediction method for binding to 22 of the most commonly expressed alleles of HLA-DR, -DP, and -DQ sequences. Peptides predicted to bind with high affinity were synthesized and tested by ELISPOT for stimulation of IFNγ production by circulating T cells of 28 latently infected, non-BCG vaccinated donors from a non-endemic area. Among the 369 reactive peptides, 80 peptides accounted for 75% of the total response. (B) Summary of one of two published screens for targets of humoral responses (11). Approximately 95% of the open reading frames of Mtb (H37Rv strain) corresponding to 3,988 proteins were cloned and expressed in vitro in an Escherichia coli-based cell-free transcription/translation system. The crude reactions containing expressed proteins were printed directly onto nitrocellulose-coated slides without purification. These slides were then probed with sera from uninfected healthy individuals from a non-endemic country (n = 64) and suspected cases of TB (TB and non-TB pulmonary patients) from endemic countries (n = 561). The proteins that reacted to sera from endemic countries but not to sera of uninfected individuals were defined as antigens associated with infection. Among 484 such antigens, 198 reacted to more than one serum from endemic countries and were designated frequent reactors. Proteins associated with disease were identified by comparing responses in TB patients and non-TB patients.