Molecular and Pathological Analysis of Chicken Anemia Virus Isolated from Field Infection in Three Egyptian Provinces

Chicken anemia virus (CAV) is a ubiquitous pathogen of chickens causing economically important disease in commercial flocks, around the globe. The present study was designed to assess the epidemiological, molecular and pathological characteristics of CAV from field infections in forty unvaccinated commercial broiler flocks in three Egyptian provinces. Important clinical features such as stunting, depression and mortalities ranged from 3-31.25% were observed. Post-mortem examination revealed pale liver, enlarged spleen and severe thymus and bursal atrophy; whilst, the major histopathologic findings were lymphoid depletion and focal hepatic necrosis. The characteristic apoptotic patterns were confirmed using TUNEL assay. Moreover, a serologic survey was performed using ELISA assay to detect CIA virus (CAV)-specific antibody. A total of 85% of the examined flocks was found seropositive while, CAV DNA was detected in 65% of the examined flocks using PCR. The phylogenetic analysis of two Egyptian CAVs indicated their grouping close to viruses previously reported from China and the Middle East. The characterized viruses were distinct from viruses recently reported from Egypt and from rest of the Africa. Furthermore, genetic matching indicated that circulating CAVs in Egypt carry marked variations compared to a commercial CAV vaccine strain (Nobilis® CAV P4) and old Egyptian CAV isolates of 1990s. Taken together, the present study highlights the significance of CAV in Egypt and proposes further studies to systemically compare the genetic divergence and vaccine matching. These findings are fundamental in any effort to control avian pathogens in the country.