Rv1985c, a promising novel antigen for diagnosis of tuberculosis infection from BCG-vaccinated controls.
BACKGROUND
Antigens encoded in the region of difference (RD) of Mycobacterium tuberculosis constitute a potential source of specific antigens for immunodiagnosis. In the present study, recombinant protein Rv1985c from RD2 was cloned, expressed, purified, immunologically characterized and investigated for its potentially diagnostic value for tuberculosis (TB) infection among BCG-vaccinated individuals.


METHODS
T-cell response to Rv1985c was evaluated by IFN-γ ELISPOT in 56 TB patients, 20 latent TB infection (LTBI) and 30 BCG-vaccinated controls in comparison with the commercial T-SPOT. TB kit. Humoral response was evaluated by ELISA in 117 TB patients, 45 LTBI and 67 BCG-vaccinated controls, including all those who had T-cell assay, in comparison with a commercial IgG kit.


RESULTS
Rv1985c was specifically recognized by cellular and humoral responses from both TB and LTBI groups compared with healthy controls. Rv1985c IgG-ELISA achieved 52% and 62% sensitivity respectively, which outperformed the sensitivity of PATHOZYME-MYCO kit (34%) in detecting active TB (P = 0.011), whereas IFN-γ Rv1985c-ELISPOT achieved 71% and 55% sensitivity in detecting active and LTBI, respectively. Addition of Rv1985c increased sensitivities of ESAT-6, CFP-10 and ESAT-6/CFP-10 combination in detecting TB from 82.1% to 89.2% (P = 0.125), 67.9% to 87.5% (P < 0.001) and 85.7% to 92.9% (P = 0.125), respectively.


CONCLUSIONS
In conclusion, Rv1985c is a novel antigen which can be used to immunologically diagnose TB infection along with other immunodominant antigens among BCG-vaccinated population.
Chen
Jiazhen
J
Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai 200040, China.
Wang
Sen
S
Zhang
Ying
Y
Su
Xiaodi
X
Wu
Jing
J
Shao
Lingyun
L
Wang
Feifei
F
Zhang
Shu
S
Weng
Xinhua
X
Wang
Honghai
H
Zhang
Wenhong
W
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology*; D001500:BCG Vaccine / Q000276:immunology; D001431:Bacteriological Techniques / Q000379:methods*; D002648:Child; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000378:metabolism; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology; D014376:Tuberculosis / Q000175:diagnosis*; D055815:Young Adult
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001500:BCG Vaccine; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D007371:Interferon-gamma