STANDARDIZATION OF A DOT-BLOT IMMUNOASSAY FOR ANTIGEN-DETECTION IN CASES OF PULMONARY TUBERCULOSIS AND ITS EVALUATION WITH RESPECT TO THE CONVENTIONAL TECHNIQUES

A simple dot (blot) ELISA test for detecting tubercular antigen in spu tum samples of patients of pulmonary tuberculosis has been standardize d using nitrocellulose paper. The sensitivity of the assay is 20 ng/ml . The cut-off value was 80 ng/ml. Of the 1042 patients in the study gr oup, the percentage positivity by smear and culture was 54.51 and 57.9 3 per cent respectively; 68.7 per cent of the ELISA positives were con firmed by smear. The dot blot ELISA could be used as a rapid and speci fic test as it not only picked up 88.88 per cent of the smear positive , culture positive cases but also 81.89 per cent of the smear negative , culture positive cases. If the results of smear and dot blot ELISA a re combined, 91.08 per cent of the culture positive cases were picked up as positive. If such a noninvasive test is commercialized and used in conjunction with smear, the pick up rate of tuberculosis cases will improve considerably.