Jar. Conlon et Pe. Shewen, CLINICAL AND SEROLOGICAL EVALUATION OF A PASTEURELLA-HAEMOLYTICA A1 CAPSULAR POLYSACCHARIDE VACCINE, Vaccine, 11(7), 1993, pp. 767-772
The purified capsular polysaccharide (CPS) of Pasteurella haemolytica
Al was examined for its ability to protect cattle from experimental ch
allenge with logarithmic-phase P. haemolytica. Several preparations of
P. haemolytica antigens were utilized in the experiment including CPS
, log-phase P. haemolytica culture supernatant, P. haemolytica recombi
nant leucotoxin (rLKt) and various combinations of the above. CPS alon
e or in combination with culture supernatant or rLkt elicited no prote
ction; rather, administration of CPS was associated with a high incide
nce of anaphylaxis (36% of calves). Although a classical biphasic humo
ral immune response to CPS could be detected in all calves that receiv
ed this compound, this T-dependent response was not correlated with re
sistance to experimental challenge. The complexity of protective immun
ity in pneumonic pasteurellosis is emphasized by this study, and clini
cal anaphylaxis associated with response to CPS may be implicated in t
he pathogenesis of disease.