Protection against fowl cholera in ducks immunized with a combination vaccine containing live attenuated duck enteritis virus and recombinant outer membrane protein H of Pasteurella multocida

Fowl cholera are highly contagious diseases within the global duck farming industry. This study aimed at formulating and evaluating the protective efficacy of a combination vaccine containing a recombinant outer membrane protein H (rOmpH) of Pasteurella multocida strain X-73 with a live attenuated duck plague vaccine into a single dose. Four groups of ducks received different treatments and the groups were labelled as non-vaccinated, combined vaccination, duck plague vaccination and rOmpH vaccination, respectively. The combined vaccination group was comprised of live attenuated duck plague commercial vaccine with 100 µg rOmpH to a total volume of 0.5 ml/duck/intramuscular administration. All groups were challenged with avian P. multocida strain of X-73 via intranasal administration. In addition, blood samples were collected monthly over a period of 6 months to determine the appropriate antibody level by indirect ELISA. The indirect ELISA results in the combination vaccine group revealed that the levels of the average serum antibody against the duck enteritis virus (0.477 ± 0.155) and fowl cholera (0.383 ± 0.100) were significantly higher than those values in the unvaccinated control group (0.080 ± 0.027 and 0.052 ± 0.017), respectively (P < 0.05). Moreover, all vaccinated ducks were effectively protected from fowl cholera. This preliminary study indicated that a combination vaccine did not affect the antibody response in the subjects, while protecting the ducks against experimental P. multocida infection. This combination vaccine should be considered part of an alternative pre-treatment strategy that could replace the monovalent vaccine.