An Inactivated Vaccine for Prevention and Control of Inclusion Body Hepatitis in Broiler Breeders

Abstract

Inclusion bodies hepatitis (IBH) in Thailand is caused by Fowl Adenovirus (FAdv) serotype 2. Vertical transmission is the important route for disease outbreak. Biosecurity and vaccination are the major keys for disease control and prevention. Vaccination of broiler breeders results in maternal antibody production that can be transferred to their progenies. Therefore, the aim of present study was to develop an inactivated FAdv serotype 2 vaccine. The FAdv was isolated from liver of infected chickens by inoculation onto chicken embryo liver cells (CEL). Virus purification was performed and then inactivated by Binary Ethylene Imine (BEI). The 10⁷ TCID₅₀ of virus concentration was inactivated for chicken immunization. The 0.01M BEI at 37°C for 72 h was the optimal condition for FAdv inactivation. Infectivity test, virus isolation and PCR technique were used for complete virus inactivation. In addition, sterility test was performed before and after the inactivated FAdv was mixed with Montanide^™ ISA 70 VG, an adjuvant. Specific pathogen free chickens were vaccinated once during rearing period by 0.5 ml/bird intramuscular injection. Results showed a significant antibody response (p<0.05). Moreover, the embryonic eggs and chicks from the vaccinated breeders showed disease protection at 90% and 100%, respectively, when challenged with 10⁷ TCID₅₀ of FAdv serotype 2. These results suggested that the inactivated FAdv serotype 2 vaccine could be prepared locally for broiler breeder farms in Thailand.