Recognition of stage-specific mycobacterial antigens differentiates between acute and latent infections with Mycobacterium tuberculosis.
Mycobacterium tuberculosis is estimated to infect 80 to 100 million people annually, the majority of whom do not develop clinical tuberculosis (TB) but instead maintain the infection in a latent state. These individuals generally become positive in response to a tuberculin skin test and may develop clinical TB at a later date, particularly if their immune systems are compromised. Latently infected individuals are interesting for two reasons. First, they are an important reservoir of M. tuberculosis, which needs to be considered for TB control. Second, if detected prior to recrudescence of the disease, they represent a human population that is making a protective immune response to M. tuberculosis, which is very important for defining correlates of protective immunity. In this study, we show that while responsiveness to early secretory antigenic target 6 is a good marker for M. tuberculosis infection, a strong response to the 16-kDa Rv2031c antigen (HspX or alpha-crystallin) is largely restricted to latently infected individuals, offering the possibility of differential immunodiagnosis of, or therapeutic vaccination against, TB.
Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Abebech
A
Demissie
Eliane M S
EM
Leyten
Markos
M
Abebe
Liya
L
Wassie
Abraham
A
Aseffa
Getahun
G
Abate
Helen
H
Fletcher
Patrick
P
Owiafe
Philip C
PC
Hill
Roger
R
Brookes
Graham
G
Rook
Alimuddin
A
Zumla
Sandra M
SM
Arend
Michel
M
Klein
Tom H M
TH
Ottenhoff
Peter
P
Andersen
T Mark
TM
Doherty
D000208:Acute Disease; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology; D002353:Carrier State / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology; D015331:Cohort Studies; D005002:Ethiopia; D005714:Gambia; D006801:Humans; D007159:Immunologic Tests; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000096:biosynthesis; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000472:pathogenicity; D009426:Netherlands; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C093276:ESAT-6 protein, Mycobacterium tuberculosis; C118127:HspX protein, Mycobacterium tuberculosis; D007371:Interferon-gamma