Cell culture adaptation of Avipox viruses isolated from different species of birds

Abstract

Avianpox (AP) is an infectious, slow spreading viral disease that has been reported to affect numerous species of birds including poultry. There is very limited information available regarding the molecular and biological characteristics of the avipox viruses (APVs) circulating in India. In the present study, APVs from fowl [FP/As- K(R)], pigeon [P2/ As- K9(R)] and duck [D2/ As- N] origin isolated from natural outbreaks of the disease in different areas of Assam were selected for adaptation in different cell culture. All the three isolates were propagated in chicken embryo fibroblast (CEF) primary cell culture and Vero cell line and their propagation was confirmed by observing virus specific cytopathic effects (CPE) and by performing PCR targeting the 4b gene of APV. All three isolates were adapted in the CEF primary culture with production of virus specific CPE. However, a high degree of CPE was observed in the cultures infected with the fowl isolate from an earlier passage (P-11) in comparison to the other two isolates. Even the time required for completion of CPE was considerably less in case of the fowl isolate. The log TCID50 of the fowl isolate was found to be 4.18 ± 0.11, 5.29 ± 0.06 and 6.29 ± 0.13, respectively in the 5th, 15th and 20th passage, which was higher in comparison to the other two isolates. Interestingly, none of the isolates showed any virus specific CPE in vero cell line on propagation till the 10th passage. Moreover, all the passages were found to be negative by PCR.