Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/2008
Publication Date: 12/31/2008
Citation: Pandiri, Arun K.R., Cortes, Aneg L., Lee, Lucy F., Gimeno, I.M. 2008. Marek's Disease Virus Infection in the Eye: Chronological Study of the Lesions, Virus Replication, and Vaccine-Induced Protection. Avian Diseases. 52(4):572-580. Interpretive Summary: Marek's disease virus (MDV) causes maglignent tumors in chickens. The goals of this research were to chronologically study MDV infection in the eye and the effect of vaccination on the development of eye lesions. The detail description of the eye lesion is described in the summary. This is a first comprehensive study on MD development and prevention of eye lesions. This research enhances our understanding of the nature and pattern of MDV infection in the eye and effective vaccines for protection against MD induced eye lesions.
Technical Abstract: Marek’s disease virus (MDV) infection in the eye was studied chronologically after inoculating one-day-old chickens with a very virulent MDV strain Md5. Based on the location of the lesions and the severity of the distribution, lesions could be classified as early lesions (6 to 11 days post inoculation, dpi) and late lesions (26 and 56 dpi). The early lesions involved iris, ciliary body and choroid layer and were characterized by endothelial cell hypertrophy, vasculitis, and infiltration of lymphocytes (mainly CD8+), plasma cells, macrophages, and heterophils. Expression of early MDV antigen pp38 in the cells infiltrating choroid layer was detected as early as 11 dpi. Late lesions consisted of severe lymphohistiocytic uveitis, keratitis, pectenitis, vitreitis, retinitis, and segmental to diffuse retinal necrosis. Cell infiltration included macrophages, granulocytes, plasma cells, and CD4+ and CD8+ cells of various sizes. Expression of early MDV antigen pp38 was readily found in all layers of the retina, uveal tract and corneal epithelium. No expression of late antigen gB or oncogene meq was detected during the experiment. A second experiment was conducted to study the effect of vaccination on the development of eye lesions. Both HVT and CVI988 were able to protect against the development of early eye lesions in chickens infected with very virulent plus strain 648A. However, only CVI988 conferred complete protection against the development of late eye lesions. HVT conferred partial protection as it reduced the frequency and the severity of the late eye lesions. These results enhance our understanding of the nature and pattern of MDV infection in the eye. .