A conjugative plasmid with potential usefulness for vaccine strains was constructed. In the first step, a 5.9-kilobase DNA segment containing the two loci for the A and B subunits of heat-labile enterotoxin with a mutation in the gene for the A subunit was joined to the cloning vehicle pGA22, generating the nonconjugative plasmid pPMC4 with genes for resistance to tetracycline and chloramphenic...

The development of genetic transformation technology for Chlamydia trachomatis using its endogenous plasmid has recently been described. Chlamydia muridarum cannot be transformed by the C. trachomatis plasmid, indicating a barrier between chlamydial species. To determine which regions of the plasmid conferred the species specificity, we used the novel approach of transforming wild-type C. murid...