The Efficacy of Escherichia coli AroA-Live Vaccine in Broilers against Avian E. coli Serotype O78 Infection

Abstract

The efficacy of an Escherichia coli (E. coli) aroA-live vaccine in the prevention of colibacillosis in chickens following intratracheal challenge with a virulent strain of E. coli O78 was investigated. Thirty-six, one day old broiler chickens were divided into 3 groups of 12 each. Chickens in each group were randomly divided into 2 replicates. The chickens in group 1 that were not vaccinated and challenged served as a negative control. The chickens in group 2 that were not vaccinated but received E. coli serotype O78 served as a positive control. The chickens in group 3 were vaccinated by the oral route at 5 days of age with E. coli aroA-vaccine and challenged with E. coli serotype O78. All the chickens in groups 2 and 3 were challenged intratracheally at 4 weeks of age with 0.5 ml (1.2x109 cfu/ml) per dose of E. coli O78. The chickens were monitored for 7 days after infection for feed conversion ratio (FCR), and the post-mortem pathology was assessed. The results revealed that the vaccine tends to prevent E. coli infection. The chickens in group 3 tended to show lower pathological findings including airsacculitis, pericarditis, perihepatitis, peritonitis and arthritis than the chickens in group 2 but the FCR was not different in each group (p>0.05).