The isolation of recombinant plasmids expressing secreted antigens of Pasteurella haemolytica A1 and the characterization of an immunogenic 60 kDa antigen.
A collection of recombinant plasmids had been isolated which express secreted antigens of Pasteurella haemolytica A1 likely to be important in protection. The recombinant Escherichia coli clones were found to express the P. haemolytica A1 antigens by Western immunoblot analysis, using sera from calves which had been vaccinated with Presponse and were subsequently resistant to experimental challenge with P. haemolytica A1. Detailed analysis of three of the recombinant plasmids (pGS1-17, pGS3-19 and pSA1-50) showed that they all carry the same 4.2 kbp insert DNA. E. coli clones which carry the recombinant plasmids all express a strongly antigenic protein of approximately 60 kDa. Nucleotide sequence analysis of the cloned DNA showed that it codes for a polypeptide with an estimated M.W. of 60.8 kDa. A partial clone of this gene has been reported previously and an antibody response to the antigen was shown to be significantly correlated to resistance to disease. This gene was found to be present in only the A biotypes of P. haemolytica and not in the T biotypes, which have been reclassified Pasteurella trehalosi. This demonstrates that this recombinant plasmid collection codes for antigens of P. haemolytica A1 important to protection and warrants further characterization to identify additional recombinant antigens.
Lo
R Y
RY
Department of Microbiology, University of Guelph, Ontario, Canada. rlo@micro.uoguelph.ca
Mellors
A
A
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D001483:Base Sequence; D003001:Cloning, Molecular / Q000379:methods; D004926:Escherichia coli; D016978:Mannheimia haemolytica / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010957:Plasmids / Q000302:isolation & purification*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology / Q000302:isolation & purification; D015183:Restriction Mapping
D000942:Antigens, Bacterial; D011994:Recombinant Proteins