CONSTRUCTION OF CONJUGATIVE SHUTTLE AND SUICIDE VECTORS FOR PASTEURELLA-HAEMOLYTICA AND P. MULTOCIDA

A shuttle cloning vector, pAKA16, and suicide derivatives pAKA19 and pAKA22 have been developed for gene transfer to Pasteurella haemolytica and P. multocida. pAKA16 was constructed by insertion of the lacZ alpha-peptide-encoding region and a multiple cloning site into a plasmid which was originally isolated from P. haemolytica serotype A1. The vector encodes ampicillin resistance, and contains at least 14 unique restriction sites and the property of phenotypic identification of recombinant clones in Escherichia coli by insertional inactivation of beta-galactosidase activity. It can be transferred by conjugation to P. haemolytica or P. multocida and is stably maintained in both species. The type-II chloramphenicol acetyltransferase-encoding gene (cat), cloned into pAKA16, was stably expressed in both P. haemolytica and P. multocida. Plasmids pAKA19 and pAKA22 were constructed by replacement of the origin of DNA replication (ori) of pAKA16 with a Co1E1-type ori from pBR322 or an ori of plasmid R6K (oriR6K) from pJM703.1, respectively. These derivatives replicate in E. coli, but not in either P. haemolytica or P. multocida, and are suitable for use as suicide vectors for these Pasteurella species.