ABSTRACT
The 38 kDa antigen of Mycobacteriurn tuberculosis strain H37/Rv was prepared und purified from the unheated culture filtrate by alcohol fractionation after being precipitated with ammonium sulphate. The prepared antigen was evaluated in comparison with bovine tuberculin by skin sensitivity test and ELISA in guinea pigs experimentally infected with typical and atypical mycobacteria. Results indicated the ability of 38 kDa antigen to differentiate between guinea pigs infected with both types of mycobacteria. Also, the antigen was evaluated in comparison with bovine PPD using ELISA for serum samples taken from tuberculin positive and negative buffaloes. The antigen was able to distinguish infection of pathogenic potential forms from cross-reaction sensitization by environmental mycobacteria at serum dilution of 1/80. Specificity of the 38 kDa antigen was 88.9% versus to 66.7% for bovine PPD. Therefore, 38 kDa antigen is strongly suggested for serological diagnosis of bovine tuberculosis