Pathogenesis of Marek's Disease: Early Distribution of Virus and Viral Antigens in Infected Chickens23

Abstract

Further evidence supported the earlier observation that the respiratory tract of the chicken is the natural entry for Marek's disease virus (MDV). After inhalation exposure to infectious feather material, a high incidence of infection was established in 2 strains of chickens free of MDV antibody. The results indicated that virions in the feather material were taken up by phagocytic alveolar cells of the lung. Evidence of virus replication was found at that site, but the cells prominent in the early stages of infection were in lymphoid tissues. During substantial virus replication in thymus, spleen, and bursa in the 1st week post exposure, a persistent infection of white blood cells developed. No evidence of an early cell-free period of viral presence in the host was found. The signs of infection subsided briefly in the 2d week post exposure, followed by a progressive lymphoproliferation and spread of the infection to an increasing number of tissue.