Isolation and characterization of fowlpox virus of poultry
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Date
2007-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Fowl pox is a contagious and slow spreading viral disease. It affects the birds of all age, sex and breeds. The disease is manifested in three different clinical forms–cutaneous, diphtheritic and oculo nasal forms. The mucosal lesions involving the mouth, esophagus and trachea can be confused with other respiratory diseases like infectious laryngotrachaetis, coryza etc. Keeping in view of the impact of disease on economics of poultry industry, the present study was undertaken to isolate the virus from scab lesions of birds of a poultry farm near Barielly following isolation of virus on chorioallantoic membrane (CAM), of developing chicken embryos, further characterization was carried by studying cytopathogenicity in cell culture and sero diagnostic tests. It was observed that virus was successfully adapted to CAM, CEF cells as well as in BHK 21 cell line. Characteristic pock lesion in CAM and CPE in unstained and stained preparations confirmed the presence of virus. In MGG staining, the cytopathic changes characterized by rounding of cells 24 hrs PI and the cytoplasmic vacuolation and syncytia formation by 48 hrs PI. In few cells, the nucleus occupied eccentric position and degenerative changes in the nucleus characterized by fragmentation of nuclear membrane in the infected CEF cells while the cytopathic changes in infected BHK 21cells were characterized by rounding of cells 36 hrs PI and the cytoplasmic vacuolation and syncytia formation by 48 hrs PI. The infectivity titre was calculated to be log104.25/ml (EID50/ml) on CAM and log10 9.79/ml (TCID50/ml) in CEF cell culture. The agar gel precipitation test (AGPT) revealed the precipitation band, which confirms the presence of antigen and antibody. Counter immunoelectrophorasis (CIE) showed a precipitation line within one hr of electrophoretic run. The indirect fluorescent antibody technique (IFAT) was used to demonstrate the virus in infected cell culture and cell line. The infected chicken embryo fibroblast cells revealed small particulate fluorescence in the cytoplasm of the cells. These tests confirmed that the virus isolate as fowlpoxvirus SDS-PAGE analysis of cell culture supernatant infected with FPV isolate revealed 11 polypeptides with molecular weights ranging from 120k Da to 15 kDa.
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