Induction of CD8 T cells against a novel epitope in TB10.4: correlation with mycobacterial virulence and the presence of a functional region of difference-1.
Although infection with Mycobacterium tuberculosis (M.tb) induces a robust CD8 T cell response, the role of CD8 T cells in the defense against M.tb, and the mechanisms behind the induction of CD8 T cells, is still not clear. TB10.4 is a recently described Ag that is expressed by both bacillus Calmette-Guérin (BCG) and M.tb. In the present study, we describe a novel CD8 T cell epitope in TB10.4, TB10.4(3-11). We show that TB10.4(3-11)-specific CD8 T cells are induced at the onset of infection and are present throughout the infection in high numbers. TB10.4(3-11) CD8 T cells were recruited to the site of infection and expressed CD44, TNF-alpha, and IFN-gamma. In addition, TB10.4(3-11) CD8 T cells showed an up-regulation of FasL and LAMP-1/2 (CD107A/B), which correlated with a strong in vivo cytolytic activity. The induction of TB10.4(3-11)-specific CD8 T cells was less pronounced following infection with BCG compared to infection with M.tb. By using a rBCG expressing the genetic region of difference-1 (RD1), we show that the presence of a functional RD1 region increases the induction of TB10.4(3-11)-specific CD8 T cells as well as the bacterial virulence. Finally, as an M.tb variant lacking the genetic region RD1 also induced a significant amount of TB10.4(3-11)-specific CD8 T cells, and exhibited increased virulence compared with BCG, our data suggest that virulence in itself is also involved in generating a robust CD8 T cell response against mycobacterial epitopes, such as TB10.4(3-11).
Billeskov
Rolf
R
Department of Infectious Disease Immunology, Statens Serum Institut, Copenhagen, Denmark.
Vingsbo-Lundberg
Carina
C
Andersen
Peter
P
Dietrich
Jes
J
D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D002465:Cell Movement / Q000276:immunology; D002470:Cell Survival / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology*; D005260:Female; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology*; D018655:Lymphocyte Count; D051379:Mice; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000276:immunology / Q000472:pathogenicity; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity*; D014376:Tuberculosis / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D015854:Up-Regulation / Q000276:immunology; D014774:Virulence / Q000235:genetics