Molecular Characterization and Human T-Cell Responses to a Member of a NovelMycobacterium tuberculosis mtb39Gene Family

• DOI: 10.1128/iai.67.6.2941-2950.1999
• Publication Date: 2019-12-31T15:35:31Z
• Authors: Davin C. Dillon; Mark R. Alderson; Craig H. Day; David M. Lewinsohn; Rhea Coler; Teresa Bement; Antonio Campos-Neto; Y. A. W. Skeiky; Ian M. Orme; Alan Roberts; Sean Steen; Wilfried Dalemans; Roberto Badaro; Steven G. Reed
• Keywords: Male; Antigens, Bacterial; 0303 health sciences; Adolescent; T-Lymphocytes; Molecular Sequence Data; Dendritic Cells; Mycobacterium tuberculosis; Middle Aged; 3. Good health; Mice, Inbred C57BL; Mice; 03 medical and health sciences; Genes, Bacterial; Multigene Family; BCG Vaccine; Leukocytes, Mononuclear; Animals; Humans; Tuberculosis; Female; Amino Acid Sequence; Rabbits

ABSTRACTWe have used expression screening of a genomicMycobacterium tuberculosislibrary with tuberculosis (TB) patient sera to identify novel genes that may be used diagnostically or in the development of a TB vaccine. Using this strategy, we have cloned a novel gene, termedmtb39a, that encodes a 39-kDa protein. Molecular characterization revealed thatmtb39ais a member of a family of three highly related genes that are conserved among strains ofM. tuberculosisandMycobacterium bovisBCG but not in other mycobacterial species tested. Immunoblot analysis demonstrated the presence of Mtb39A inM. tuberculosislysate but not in culture filtrate proteins (CFP), indicating that it is not a secreted antigen. This conclusion is strengthened by the observation that a human T-cell clone specific for purified recombinant Mtb39A protein recognized autologous dendritic cells infected with TB or pulsed with purified protein derivative (PPD) but did not respond toM. tuberculosisCFP. Purified recombinant Mtb39A elicited strong T-cell proliferative and gamma interferon responses in peripheral blood mononuclear cells from 9 of 12 PPD-positive individuals tested, and overlapping peptides were used to identify a minimum of 10 distinct T-cell epitopes. Additionally, mice immunized withmtb39aDNA have shown increased protection fromM. tuberculosischallenge, as indicated by a reduction of bacterial load. The human T-cell responses and initial animal studies provide support for further evaluation of this antigen as a possible component of a subunit vaccine forM. tuberculosis.