Submitted to: International Congress on Anthrax, Brucellosis, CBPP, Mycobacterial Disease
Publication Type: Proceedings
Publication Acceptance Date: 5/1/1998
Publication Date: N/A
Technical Abstract: In this study, we compared purified protein derivatives (PPD) prepared in the United States of America (USA) with those prepared by CSL Limited (CSL) for use with a commercial gamma interferon assay (BOVIGAM, CSL Limited, Parkville, Victoria, Australia) for diagnosis of bovine tuberculosis. We also determined the effect of skin testing on results of the gamma interferon (gIFN) assay. Twenty cattle that were sensitized by subcutaneous injection of heat-killed Mycobacterium bovis were used for this study. Cattle were randomly divided into three groups. Group A was skin tested on day 0 and day 7; group B was skin tested on day 0 and day 63; and group C was not skin tested. Blood samples for the gIFN assay were collected at various times throughout the study period. Optical density (OD) values for the gIFN assay were not significantly different when blood samples were stimulated with USA avian PPD and CSL avian PPD. The OD values were significantly higher when USA bovine PPD was used compared wit CSL bovine PPD. However, the final interpretation of the gIFN assay was the same when using either USA or CSL PPDs. In addition, OD results were significantly higher for blood samples collected after cattle were skin tested compared with samples collected from the same cattle before skin testing or from cattle not skin tested. These results indicate that skin testing cattle prior to collection of blood for the gIFN assay may boost immuno-responsiveness and improve detection of cattle infected with M. bovis.