|Haghighi, Hamid Reza|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2009
Publication Date: 9/1/2009
Citation: Abdul-Careem, M.F., Javaheri-Vayeghan, A., Shanmuganathan, S., Haghighi, H., Read, L.R., Haq, K., Hunter, D.B., Schat, K.A., Heidari, M., Sharif, S. 2009. Establishment of an Aerosal-Based Marek's Disease Virus Infection Model. Avian Diseases. 53(3):387-391. Interpretive Summary: Marek's disease (MD), a virus induced cancer like disease of chickens, is considered as a major disease problem in commercial poultry. Marek’s disease virus (MDV), the causative agent of MD is transmitted to other chickens through the respiratory route. Experimental reproduction of Marek’s disease (MD) has been commonly done either by intra-abdominal (IA) inoculation of cell-associated MDV or by exposure to MDV-infected seeder chickens. IA inoculation of chicken with MDV does not mimic the natural route of infection, while exposure to seeder chickens does not result in uniform timing or dose of virus transmission. The aim of the present study was to establish an infection model of MDV that mimics the natural route of infection. The designed model is capable of generating aerosols of cell-free MDV suspension using a nebulizer. A 20-minute exposure to aerosol particles resulted in pathological and clinical signs of Marek’s disease in 95-100% of exposed chickens. Samples taken at different time points showed MDV replication in the lungs of exposed chickens as early as one day post inoculation. This infection model is an important tool in studies directed at elucidation of MDV pathogenesis, host-pathogen interaction at the primary site of inoculation (lungs), and dissemination of virus from the lungs to different organs after exposure.
Technical Abstract: Marek’s disease virus (MDV), which is the causative agent of Marek’s disease (MD), is shed by infected chickens and transmitted to other chickens through the respiratory route. Experimental reproduction of MD has been commonly done either by intra-abdominal inoculation of cell-associated MDV or by exposure to MDV-infected seeder chickens. The former method does not mimic the natural route of MDV infection, whereas the latter method suffers from lack of uniformity in the timing and amount of virus transmission from seeder chickens to susceptible birds. The aim of the present study was to establish an infection model of MDV that mimics the natural route of infection. Here we report that when chickens were exposed for a brief period (20 minutes) to aerosols (particle size 1.91 µm) of cell-free MDV suspension (1280 PFU/ml), which were generated using a nebulizer, pathological and clinical signs of Marek’s disease were observed in 95-100% of the aerosol-exposed chickens by 21 days post-infection (d.p.i.). Chickens that were exposed to aerosols and sampled at 1, 2, 3, 10 and 21 d.p.i. showed MDV replication as early as 1 d.p.i. in lungs as well as in extra-respiratory tissues such as spleen and bursa of Fabricius. This infection model will facilitate the studies directed to elucidate MDV-host interaction at the site of virus entry.