THE ISOLATION OF RECOMBINANT PLASMIDS EXPRESSING SECRETED ANTIGENS OFPASTEURELLA-HAEMOLYTICA-A1 AND THE CHARACTERIZATION OF AN IMMUNOGENIC60-KDA ANTIGEN
Ryc. Lo et A. Mellors, THE ISOLATION OF RECOMBINANT PLASMIDS EXPRESSING SECRETED ANTIGENS OFPASTEURELLA-HAEMOLYTICA-A1 AND THE CHARACTERIZATION OF AN IMMUNOGENIC60-KDA ANTIGEN, Veterinary microbiology, 51(3-4), 1996, pp. 381-391
A collection of recombinant plasmids had been isolated which express s
ecreted antigens of Pasteurella haemolytica A1 likely to be important
in protection. The recombinant Escherichia coli clones were found to e
xpress the. haemolytica A1 antigens by Western immunoblot analysis, us
ing sera from calves which had been vaccinated with Presponse(TM) and
were subsequently resistant to experimental challenge with P. haemolyt
ica A1. Detailed analysis of three of the recombinant plasmids (pGS1-1
7, pGS3-19 and pSA1-50) showed that they all carry the same 4.2 kbp in
sert DNA, E. coli clones which carry the recombinant plasmids all expr
ess a strongly antigenic protein of approximately 60 kDa. Nucleotide s
equence analysis of the cloned DNA showed that it codes for a polypept
ide with an estimated M.W. of 60.8 kDa. A partial clone of this gene h
as been reported previously and an antibody response to the antigen wa
s 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 tr
ehalosi. This demonstrates that this recombinant plasmid collection co
des for antigens of P. haemolytica A1 important to protection and warr
ants further characterization to identify additional recombinant antig
ens.