title: Molecular characterization and human T-cell responses to a member of a novel Mycobacterium tuberculosis mtb39 gene family.
abstract: We have used expression screening of a genomic Mycobacterium tuberculosis library 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, termed mtb39a, that encodes a 39-kDa protein. Molecular characterization revealed that mtb39a is a member of a family of three highly related genes that are conserved among strains of M. tuberculosis and Mycobacterium bovis BCG but not in other mycobacterial species tested. Immunoblot analysis demonstrated the presence of Mtb39A in M. tuberculosis lysate 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 to M. tuberculosis CFP. 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 with mtb39a DNA have shown increased protection from M. tuberculosis challenge, 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 for M.tuberculosis.
authors.affiliation: Corixa Corporation, Seattle, Washington 98104, USA. dillon@corixa.com
authors.forename: D C
authors.initials: DC
authors.lastname: Dillon
authors.forename: M R
authors.initials: MR
authors.lastname: Alderson
authors.forename: C H
authors.initials: CH
authors.lastname: Day
authors.forename: D M
authors.initials: DM
authors.lastname: Lewinsohn
authors.forename: R
authors.initials: R
authors.lastname: Coler
authors.forename: T
authors.initials: T
authors.lastname: Bement
authors.forename: A
authors.initials: A
authors.lastname: Campos-Neto
authors.forename: Y A
authors.initials: YA
authors.lastname: Skeiky
authors.forename: I M
authors.initials: IM
authors.lastname: Orme
authors.forename: A
authors.initials: A
authors.lastname: Roberts
authors.forename: S
authors.initials: S
authors.lastname: Steen
authors.forename: W
authors.initials: W
authors.lastname: Dalemans
authors.forename: R
authors.initials: R
authors.lastname: Badaro
authors.forename: S G
authors.initials: SG
authors.lastname: Reed
mesh_terms: D000293:Adolescent; D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics* / Q000276:immunology; D001500:BCG Vaccine / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D008969:Molecular Sequence Data; D005810:Multigene Family; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000276:immunology*; D011817:Rabbits; D013601:T-Lymphocytes / Q000276:immunology*; D014376:Tuberculosis / Q000097:blood / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001500:BCG Vaccine; D019444:Vaccines, DNA