A WESTERN-BLOT CHARACTERIZATION OF MYCOBACTERIUM-BOVIS ANTIGENS RECOGNIZED BY CATTLE SERA

The immune response to Mycobacterium bovis in cattle was assessed by W estern blot. The antibody recognition pattern to M. bovis whole cell e xtracts and culture supernatant antigens was studied by using sera fro m M. bovis-infected (n=62) and healthy (n=38) cattle. Although the rec ognition patterns were highly variable, some proteins were regularly d etected, mainly those with molecular masses of 17, 23, 28, 42, 66, 71 and 80 kDa in cellular extracts, and with molecular masses of 23 and 3 3 kDa in supernatants. Whole cell extract antigens were more frequentl y recognized than culture supernatant antigens. Healthy controls produ ced only a weak antibody response. The antibody response was variable, depending on tuberculosis stage. In early stages very few antibodies were detected. A response against the 66-kDa stress protein was mounte d in intermediate tuberculosis and remained stable in more advanced di sease. In late diseases, the preferentially recognized antigens were a 28-kDa cellular protein and supernatant antigens. The 28-kDa protein was studied in some detail. As determined by using monoclonal antibodi es, the 28-kDa protein is different from superoxide dismutase. This pr otein aggregated in stored cell extracts and was not totally transferr ed to nitrocellulose. The principal conclusions of this work are: (i) whole cell extract proteins are more frequently recognized than the se creted proteins and (ii) a 28-kDa protein is a major antigen in late d isease.