title: Association of strong immune responses to PPE protein Rv1168c with active tuberculosis.
abstract: Accurate diagnosis of tuberculosis (TB) infection is critical for the treatment, prevention, and control of TB. Conventional diagnostic tests based on purified protein derivative (PPD) do not achieve the required diagnostic sensitivity. Therefore, in this study, we have evaluated the immunogenic properties of Rv1168c, a member of the PPE family, in comparison with PPD, which is routinely used in the tuberculin test, and Hsp60 and ESAT-6, well-known immunodominant antigens of Mycobacterium tuberculosis. In a conventional enzyme immunoassay, the recombinant Rv1168c protein displayed stronger immunoreactivity against the sera obtained from patients with clinically active TB than did PPD, Hsp60, or ESAT-6 and could distinguish TB patients from Mycobacterium bovis BCG-vaccinated controls. Interestingly, Rv1168c antigen permits diagnosis of smear-negative pulmonary TB as well as extrapulmonary TB cases, which are often difficult to diagnose by conventional tests. The immunodominant nature of Rv1168c makes it a promising candidate to use in serodiagnosis of TB. In addition, our studies also show that Rv1168c is a potent T-cell antigen which elicits a strong gamma interferon response in sensitized peripheral blood mononuclear cells obtained from TB patients.
authors.affiliation: Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, Andhra Pradesh, India.
authors.forename: Nooruddin
authors.initials: N
authors.lastname: Khan
authors.forename: Kaiser
authors.initials: K
authors.lastname: Alam
authors.forename: Shiny
authors.initials: S
authors.lastname: Nair
authors.forename: Vijaya Lakshmi
authors.initials: VL
authors.lastname: Valluri
authors.forename: Kolluri J R
authors.initials: KJ
authors.lastname: Murthy
authors.forename: Sangita
authors.initials: S
authors.lastname: Mukhopadhyay
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology* / Q000378:metabolism; D001500:BCG Vaccine / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology* / Q000378:metabolism; D018834:Chaperonin 60 / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology; D014373:Tuberculin / Q000276:immunology; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001500:BCG Vaccine; D001426:Bacterial Proteins; D018834:Chaperonin 60; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D011994:Recombinant Proteins; C530985:Rv1168c protein, Mycobacterium tuberculosis; D014373:Tuberculin; D007371:Interferon-gamma