Detection of Aujeszky's disease virus in nasal cells of fattening pigs by immunoassay

Both conventional and specific pathogen free pigs were inoculated intranasally with a strain of Aujeszky's disease virus (ADV). Nasal cells were collected daily by swab, aspiration or wash. The nasal cells were examined for ADV by isolation on cell culture, direct or indirect immunofluorescence and immunoperoxidase staining by monoclonal antibodies. The infected pigs were studied for nasal shedding of infected cells until 30 days after infection. The study was also extended to naturally infected farm pigs. Swabbing, washing and aspiration proved effective methods of collecting between 10(5) and 10(8) pavement or columnar epithelial cells and non-epithelial cells. Macrophages and polymorphonuclear leucocytes were also identified. Infected nasal cells were detected by immunofluorescence and immunoperoxidase from one to 21 days after infection. The viral antigen was detected in both epithelial and non-epithelial cells, the fluorescence was nuclear and, or, 'cytoplasmic', in the latter case only the cell membrane was stained. ADV antigens were detected in nasal cavity cells in pigs infected with a virulent and a hypovirulent strain. Nasal swabs proved effective in confirming infection both by virus isolation and immunological assay, and the latter was shown to be a useful experimental tool for the rapid diagnosis of Aujeszky's disease virus infection in fattening pigs suffering from acute respiratory distress.