Evaluation of the protection provided by an inactivated trivalent Pasteurella multocida vaccine against experimental Pasteurella infection and pasteurellosis in commercial environment (original) (raw)
Although chronic pasteurellosis and nasal P. multocida carriage still causes considerable losses of breeding females preventive vaccination is not routinely used. Unsatisfactory field results might stay behind that but observations from controlled field trials are lacking. In this study the protective effect of an inactivated trivalent P. multocida vaccine was evaluated in heterologous challenge experiment and field trial. The experimental vaccine contained three different P. multocida strains specific of the farm involved in the present study. Bacteria were inactivated with thiomersal and adjuvanted with Al(OH) 3 . Repeated immunization raised up the specific antibody level four times in SPF rabbits. It conferred protection against challenge with heterologous strains in commercial rabbits which was proven by lower rectal temperature, less number of days with appearance of disease signs, smaller change of body weight, and elevated antibody level. In the field study positive effect of vaccination on nasal colonization with P. multocida was found. But an adverse effect was observed: there was a lower number of total born, lower proportion of alive new-born rabbits, and furthermore a higher proportion of sucklings mortality in the case of immunized females. This might be related to the time point (i.e. some days before artificial insemination) chosen for immunization.
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