Natural pox and herpes as a dual virus infection in chickens.

A natural dual viral infection was confirmed in chickens of University of Illinois Poultry Farm by histopathologic, immunologic, and electron-microscopic examination of formalin-fixed tracheal tissue. Histopathologic examination of the tracheal mucosa revealed eosinophilic cytoplasmic inclusions characteristic of fowlpox and intranuclear inclusions suggestive of Marek's disease. Treatment of the formalin-fixed tracheal tissue with peroxidase and fluorescent-labeled antibody against Marek's disease virus revealed specificity of the reaction. Electron microscopy showed viral particles of two morphologic forms, i.e., pox and herpes. A single cell having dual infection with herpes virus in the nucleus and pox virus in the cytoplasm was also encountered on electron-microscopic examination.