Comparative Sequence Analysis, Pathogenicity and Immunogenicity of Attenuated Fowl Adenovirus Isolates as Experimental Vaccines against Inclusion Body Hepatitis of Commercial Broiler Chickens

and compared based on sequence analysis of and genes. Their pathogenicities and determined in the chickens. Groups of were inoculated with 0.5ml chicken-embryonated-derived attenuated FAdV isolates via oral and IP routes and trachea, and gizzard collected at days 3, 7, 14 and 21post-inoculation. Results: Molecular analysis revealed both isolates had 99.1% and 97.3% homologies in the L1 loop region of hexon gene and knob region of fiber gene, respectively. Molecular changes in UPM1137E20 were prominent in the knob of fiber gens with 3 amino acid changes, while for UPM1137CEL35, notable in the L1 loop region with 3 amino acid changes. It was demonstrated that both attenuated isolates are non-pathogenic and safe in commercial broiler chickens. Neither gross nor histopathological lesions were recorded in all tested groups. Both isolates induced high antibody response significantly via intraperitoneal route when compared to the control. Conclusion: UPM1137E20 isolate had a high potential to be further evaluated as a live attenuated vaccine against viral poultry diseases such as IBH.