Where does the egg-drop syndrome (EDS-76) virus primarily replicate and cause pathological damage within the hen's reproductive organs?

Egg-drop syndrome 1976 (EDS-76) is caused by an avian adenovirus that targets the reproductive tract of laying hens. The primary site of viral replication and pathological damage is the pouch-like shell gland (uterus). After ingestion or vertical transmission, the virus undergoes initial replication in the nasal mucosa and lymphoid tissues before localizing in the active oviduct. Once inside the shell gland, the virus replicates inside the nuclei of the mucosal epithelial cells, causing severe deciliation, glandular atrophy, and inflammatory cell infiltration. This localized destruction halts the secretion of uterine fluid, calcium ions, and the shell matrix, leading to the sudden production of shell-less, soft-shelled, or thin-shelled eggs, as well as complete loss of shell pigmentation. Because the rest of the oviduct remains largely unaffected, internal egg quality is maintained, but the outer shell is ruined. Farmers can study viral pathology in the Poultry Encyclopedia, purchase disinfectants and virucides on Poultry Plaza, analyze price drops on Poultry Rates, and trade recovered flocks on Murghi Mandi.