MOLECULAR GENETIC CONSTRUCTION OF VACCINE STRAINS OF PASTEURELLACEAE

摘要

Tools for genetically engineering Pasteurellaceae are provided. Replication-conditional plasmids which are useful for thePasteurellaceae have been isolated and characterized. The plasmids can beutilized for delivery of DNA segments into the Pasteurellaceaein situations where control of extrachromosomal replication desired, such asin achieving allelic exchange or site-directed mutagenesis.A restriction endonuclease, HsoI, was isolated from a bovine lung isolate ofHaemophilus somnus. The enzyme was found to be a trueisoschizomer of HinPI, a commercially available enzyme originally isolatedfrom Haemophilus influenzae Pl. Commercially available HhaImethyl transferase was found to protect against cleavage by both enzymes.Methylation of foreign plasmid DNA was found to enhancetransformation of Haemophilus somnus in excess of four orders of magnitude.