• Immunodiagnosis of pulmonary tuberculosis by concomitant detection of antigen and antibodies of excretory-secretory protein ofMycobacterium tuberculosis H37Ra

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    • Keywords

       

      Mycobacterium tuberculosis ; ES antigen; affinity purified antibodies; immunodiagnosis; pulmonary tuberculosis; ELISA

    • Abstract

       

      With a view to diagnosing tuberculosis in populations in endemic areas, excretory-secretory antigen fraction(Mtb EST-6) of purifiedMycobacterium tuberculosis H37Ra and affinity purified polyclonal antibodies againstMtb EST were used to detect both antibodies and circulating antigen in the sera of patients and disease-free individuals. Indirect stick penicillinase ELISA system usingMtb EST-6 detected antigen-specific IgG antibody in 84% of sputum positive, 77% of sputum negative pulmonary tuberculosis patients and 7% of healthy and 11% of subjects with nontub~rculosis diseases. Similarly, a sandwich penicillinase ELISA system using affinity purified antiMtb EST antibodies detected circulating antigen in 83% and 61% of sputum positive and negative pulmonary tuberculosis subjects. In contrast only 24% of healthy and 18% of disease controls showed seropositivity. Antibody assay showed higher sensitivity and specificity (83% and 91% respectively) compared to antigen detection (sensitivity of 79% and specificity of 79%). However, by concomitant use of both assays it was possible to enhance the specificity of detection to 98%, though sensitivity was reduced marginally to 70%. The present study confirms the presence of both antigen and specific antibodies in the circulation during clinical disease and draws attention to the utility ofMtb EST-6 as a diagnostic marker of pulmonary tuberculosis.

    • Author Affiliations

       

      A N Lodam1 M V R Reddy1 B C Harinath1

      1. Jamnalal Bajaj Tropical Disease Research Centre and Department of Biochemistry, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha - 442 102, India
    • Dates

       
  • Journal of Biosciences | News

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