Immunogenicity of antigens from the TbD1 region present in M. africanum and missing from "modern" M. tuberculosis: a cross- sectional study.
BACKGROUND
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.


METHODS
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.


RESULTS
Antigens from the TbD1 region induced IFNgamma responses in only 35% patients and did not discriminate between patients infected with M. africanum vs. M. tuberculosis, while PPD induced universally high responses.


CONCLUSIONS
Further studies will need to assess other antigens unique to M. africanum that may induce discriminatory immune responses.
de Jong
Bouke C
BC
Bacterial Diseases Programme, MRC Laboratories, POB 273, Banjul, the Gambia. bdejong@mrc.gm
Hammond
Abdulrahman
A
Otu
Jacob K
JK
Antonio
Martin
M
Adegbola
Richard A
RA
Ota
Martin O
MO
D000942:Antigens, Bacterial / Q000276:immunology*; D015373:Bacterial Typing Techniques; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005714:Gambia / Q000453:epidemiology; D005838:Genotype; D006801:Humans; D055985:Latent Tuberculosis / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology*; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000276:immunology*; D012680:Sensitivity and Specificity; D013045:Species Specificity
D000942:Antigens, Bacterial