Construction of a genomic DNA library of Mycobacterium paratuberculosis
A recombinant DNA library of Mycobacterium paratuberculosis, the causative agent of Johne`s disease, has been constructed in the E. Coli expression vector phage lambda gt11. The library contains 2.2x105 individual recombinant phage. When 10 of the phage DNA-bacterial DNA recombinants were examined by restriction endonuclease analysis, bacterial DNA inserts ranging in size from 1.5 to 4 kilobases were identified. Screening of the library with pooled, hyperimmune sera, prepared in mice by repeated injection with M. paratuberculosis, established that the bacterial DNA inserts were functional and that a number of phage were producing mycobacterial antigens. Further studies will attempt to identify which of the phage recombinants contain DNA specific for M. paratuberculosis. DNA specific for M. tuberculosis and M. avium are used as the bases for diagnostic tests in man. Similar tests using M. paratuberculosis-specific DNAmight provide a means of rapid identification of animals in the preclinical stages of Johne`s disease. A detailed description of the library`s construction is in preparation.