Characterization of epitopes involved in the neutralization of Pasteurella haemolytica serotype A1 leukotoxin

Article Abstract:

Defined portions of the leukotoxin A gene (lktA) from an A1 serotype of Pasteurella haemolytica were cloned into a plasmid vector and expressed as LacZ-alpha fusion proteins. The epitope recognized by a strongly neutralizing monoclonal antibody was localized to a 32 amino acid region near the C terminus of the leukotoxin A (LktA) molecule. The epitope recognized by a non-neutralizing antibody was localized to a 33 amino acid region immediately adjacent. Smaller recombinant peptides with these epitopes were not antigenic, but a polypeptide encompassing 229 amino acids at the C terminus stimulated neutralizing antibodies when utilized to immunize specific-pathogen-free lambs.

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Intra-specific diversity and host specificity within Pasteurella haemolytica based on variation of capsular polysaccharide, lipopolysaccharide and outer-membrane proteins

Article Abstract:

There are significant differences in the isolation rates of Pasteurella haemolytica capsular serotypes from cattle and sheep. Serotypes A1 and A2 are dominant pathogens in cattle and sheep respectively. A wider range of serotypes are associated with the latter than the former. P. haemolytica lipopolysaccharide shows diversity in the core-oligosaccharide region and is associated with only a single O-antigen type. Outer-membrane protein profiles can differentiate between bovine and ovine isolates and those of serotypes A7, A11, and A13 show a greater diversity.

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The Pasteurella haemolytica 35 kDa iron-regulated protein is an FbpA homologue

Article Abstract:

The fbpA gene encoding the 35 kDa protein derived from the Pasteurella haemolytica was identified and described using a P. haemolytica phagemid library to complement an iron-utilization-deficient strain of Escherichia coli. It was presumed that the 35 kDa protein may be a ferric-ion-binding protein homologue assembled in a three-gene operon resembling the other fbpABC operons. It was discovered that the FbpA was a periplasmic entity with a large degree of divergence within species due to biological constraints influencing variation.

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