Vaccine Development From Serotypes 01, 02 and 078 of Escherichia Coli Against Avian Colibacillosis

Abstract

A trivalent Escherichia coli vaccine (TECA) was prepared from serotypes O1, O2 and O78 and one series of TECA was combined with an inactivated Newcastle Disease vaccine. TECA and combined vaccine were experimentally investigated for immunogenic effects in pullets and hens. This study was carried out at two stages consisting of rearing and laying periods: (1) A number of fourty chicks aged 15 days were subcutaneously vaccinated with 0.2 ml TECA. A similar group served as nonvaccinated controls. Half of the vaccinated group were revaccinated with 0.5 ml TECA at 71 days of age. The vaccinated and nonvaccinated pullets were challenged at 30 days after vaccinations. (2) Untreated breeder hens were vaccinated with TECA and combined vaccine by 0.5 ml, via SC route at 17 age of weeks. After vaccinations, the blood samples were taken from chicks/pullets with 15 days intervals and from the hens with 21 days intervals and then tested against O1, O2 ve O78 somatic "O" and pilus antigens by micro serum agglutination test (mSAT) and rapid agglutination test (RAT). The antibody titers in pullets vaccinated once or twice were found to be similar to0.5-3.6 times higher than controls, respectively. In breeder hens, the antibody titer figures were observed similar to1.5-4.8 times higher than those from nonvaccinated hens. By challange trials with homologous E. coli serotypes, the rates of protection in vaccinated and nonvaccinated pullets were found to be 77.8 and 46.7 %, respectively. The mortality rates of the chicks from the hens which had been vaccinated with TECA and combined vaccine or not been vaccinated were as follows: % 8.8. % 13.3 and % 50.3, respectively. In conclusion, TECH could be recommended for protection of both chicks and layers to E. coli infections. We also suggest that to comine inactivated E. coli with Newcastle vaccines could be useful.