Abstract
Aim:The objective of the present study was to examine pock forming ability of field strain and vaccine strain of fowl pox virus (FPV) in chorioallantoic membrane (CAM) of embryonated chicken eggs and its adaptation in chicken embryo fibroblast (CEF) cell culture.Materials and Methods:Dry scabs were collected from 25 affected birds in glycerin-saline and preserved at 4°C until processed. Virus was isolated in 10-day-old embryonated chicken eggs by dropped CAM method. The identity of the virus is confirmed by clinical findings of affected birds, pock morphology and histopathology of infected CAM. In addition one field isolate and vaccine strain of FPV was adapted to CEF cell culture. CEF cell culture was prepared from 9-day-old embryonated chicken eggs.Result:Clinical symptoms observed in affected birds include pox lesion on comb, wattle, eyelids and legs, no internal lesions were observed. All field isolates produced similar findings in CAM. Pocks produced by field isolates ranged from 3 mm to 5 mm at the third passage while initial passages edematous thickening and necrosis of CAM was observed. Pocks formed by lyophilized strain were ranges from 0.5 mm to 2.5 mm in diameter scattered all over the membrane at the first passage. Intra-cytoplasmic inclusion bodies are found on histopathology of CAM. At third passage level, the CEF inoculated with FPV showed characteristic cytopathic effect (CPE) included aggregation of cells, syncytia and plaque formation.Conclusion:FPV field isolates and vaccine strain produced distinct pock lesions on CAMs. Infected CAM showed intracytoplasmic inclusion bodies. The CEF inoculated with FPV field isolate as well as a vaccine strain showed characteristic CPE at third passage level.
Highlights
Fowl pox is a contagious disease of domestic and wild birds [1] of all ages, sexes and breeds [2] which is caused by fowl pox virus (FPV), a DNA virus that comes under the genus Avipoxvirus of family Poxviridae and subfamily Chordopoxvirinae [3]
At the gross examination characteristics, pock lesions were observed in fowl pox infected chorioallantoic membrane (CAM)
Result of the present study clearly indicated that pock lesions of variable diameter were appeared on the CAM of scab sample inoculated embryonated chicken eggs
Summary
Fowl pox is a contagious disease of domestic and wild birds [1] of all ages, sexes and breeds [2] which is caused by fowl pox virus (FPV), a DNA virus that comes under the genus Avipoxvirus of family Poxviridae and subfamily Chordopoxvirinae [3]. Virus are spread by insects [7] and wild birds [8]. The affected birds show three forms of the disease namely; the cutaneous, diphtheritic and systemic form [9,10]. The characteristics feature of a diphtheritic form is fibro-necrotic lesions in the mucous lining of the oropharyngeal route [2] and the internal tissues are found to be most affected in the third form [9]
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