Embryo vaccination of chickens with turkey herpesvirus: Characteristics of the target cell of early viral replication in embryonic lung

Inoculation of turkey herpesvirus (HVT) into chicken eggs at the 17th day of embryonation resulted in recovery of high titres of the virus from the lung of the embryo. Infection of the lung was not characterised by extensive virus-induced cell lysis because in situ viral internal antigen (VIA) of HVT was not detected. Examination of single cell suspensions of lungs from embryos at peak viral activity revealed that the target cells of virus infection were adherent and lacked surface antigens detectable by antisera against chicken thymo-cytes, bursa cells and la antigens. Adherent lung cells were cultured in vitro and examined for VIA. After 24 hours of culture, VIA staining was detected in elongated cells that had morphologic resemblance to fibroblastoid or epithelioid cells. These results indicated that the target cell of early HVT infection in the embryonic lung was likely a non-lymphoid, non-macrophage cell.