Immunogenicity of antigens from the TbD1 region present in M. africanum and missing from "modern" M. tuberculosis: a cross- sectional study
1 Bacterial Diseases Programme, MRC Laboratories, POB 273, Banjul, the Gambia
2 New York University, 550 First Avenue, Smilow 901, New York, NY 10016, USA
3 FMPOS, University of Bamako, Point G, Bamako, Mali
BMC Infectious Diseases 2010, 10:11 doi:10.1186/1471-2334-10-11Published: 19 January 2010
Currently available tools cannot be used to distinguish between sub-species of the M. tuberculosis complex causing latent tuberculosis (TB) infection. M. africanum causes up to half of TB in West- Africa and its relatively lower progression to disease suggests the presence of a large reservoir of latent infection relative to M. tuberculosis.
We assessed the immunogenicity of the TbD1 region, present in M. africanum and absent from "modern" M. tuberculosis, in an ELISPOT assay using cells from confirmed M. africanum or M. tuberculosis infected TB patients without HIV infection in the Gambia.
Antigens from the TbD1 region induced IFNγ responses in only 35% patients and did not discriminate between patients infected with M. africanum vs. M. tuberculosis, while PPD induced universally high responses.
Further studies will need to assess other antigens unique to M. africanum that may induce discriminatory immune responses.