Protective immunity and serum agglutinin level in ducks vaccinated with duck cholera vaccines : a comparative study of various adjuvant vaccines

Abstract

The immune response in ducks against formalin-killed Pasteurella multocida serotype 8:A, a duck strain, was studied. The vaccines, three with adjuvants and one without were prepared. The vaccines were administered once and twice. The tube agglutination (TA) titer the indirect hemagglutination (IHA) titer and the extent of protection afford in terms of a percentage determined. A comparison of various antigens for the detection of Ta titer was carried out. The autoclaved antigen was found to be the best while no antibody titer was detected when using an HC1-treated, fromalinized, or living antigen. An IHA test was developed for the purpose of detecting antibody. From this it was found that IHA titer (1:268) was higher than the Ta titer (1:125) at 15 days postvaccination in the MDC group. The other adjuvanted vaccines yielded the same results. However, in non adjuvanted vaccines, the titer, as detected by IHA test, was lower than that detected by TA test. Mineral-oil-adjuvanted (MDC) vaccine induced the highest geometric mean titer (GMT), viz 1:125, at 15 days postvaccination, while aluminium hydroxide-absorbed (ADC) vaccine produced a lower titer, viz 1:48 and corn-oil-adjuvanted (CDC) vaccine the lowest viz 1:44 –as measured by the TA test. As measured by the IHA test, MDC vaccine also induced the highest GMT at 15 days postvaccination, 1:268, followed by the ADC vaccine, 1:161, and the CDC vaccine, 1:80. The difference between these titers was not statistically significant (P > 0.05). In male and female ducks, there seems to be no effect interms of immune response. Antibody titer after the 2nd vaccination measured by the TA test were lower than that after the first one in all of the vaccine groups and were statistically significant (P < 0.05). High titers were obtained after the 2nd vaccination as measured by the IHA test in all adjuvanted vaccine groups, but there was no statistically difference (P > 0.05). One injection of MDC, ADC and FDC vaccines, as measured by the percentage of survival and the calculations relating to potency at 60 days postvaccination was 85.8%, 85.8% 85.8% and 52.4% respectively. Two infections of MDC, CDC, FDC, and DCL vaccine produce a level of immunity lasting for upto 5½ moths. The percentage of potency afforded by MDC, CDC, FDC, and DCL vaccine was 60.8%, 65.8%, and 85.8%, respectively.