Seroprevalence of Fowl Adenovirus-4 using specific ELISA in backyards chickens, Golestan province, Iran: The first study.

Infection with fowl adenovirus is associated with different diseases, including hepatitis hydro pericardium syndrome (HHS), inclusion body hepatitis (IBH), and gizzard erosion. Infection with serotype 4 of fowl adenovirus can lead to HHS, which affects 3-to5-week chickens and can result in high mortality and significant financial losses. The first detection of HHS in Iran was announced in March 2021 in a broiler flock. Fowl adenovirus can be detected using various serological and molecular methods, such as Polymerase Chain Reaction and Real-Time Polymerase Chain Reaction. In the current study, the level of specific antibodies against the FAdV-4 serotype in 44 blood samples from unvaccinated backyard chicken flocks in Golestan Province, northern Iran, was evaluated using ELISA assay. According to the ELISA results, the overall prevalence was 22.72%, with the highest prevalence found in Saad Abad village at 66.66%. The results also show that the highest antibody titer was found in the Haji Balkhan group (1679.91), and the lowest was found in the Amir Abad group (3.22). Most other titers were between 100 and 300. This study is the first serological investigation of FAdV-4 in Iranian backyard chickens. While the virus can only be detected using molecular techniques, such as PCR, these findings may provide insight into the virus's spread in the northern region of Iran and help develop innovative vaccination strategies.