SEROPREVALENCE STUDY, ISOLATION AND REPLICATION OF EDS-76 VIRUS IN CHICKEN EMBRYO FIBROBLASTS

Abstract

Egg drop syndrom caused by a hemagglutinating adenovirus a member of genus atadenovirus under the family adenoviridae. This is of high economic importance due to its drastic negative effects on egg production in laying birds throughout the world including Bangladesh. The loss incurred by poultry industry due to reduced productivity, culling and cost of medicine is considered to be often greater than loss due to mortality. The present study was undertaken to assess the seroprevalence of egg drop syndrome (EDS- 76) virus in 5 farms of Nilphamari district by haemagglutination inhibition (HI) test. For this a total of 30 sera samples were collected from Nilphamari district. The overall seroprevalence was 60.01%. The highest seroprevalence was at Master Para and Kishorgong and lowest at Ramnagar. The seropositive was more in vaccinated birds. For virus isolation a total of 20 samples (cloacal swab and abnormal egg washing) were collected from 5 different farms of Nilphamari District. In chicken embryo fibroblast EDS –76 grew very slowly and has been reported to exhibit a lower growth rate. The samples were inoculated into 11 days old duck embryo and 2 virus isolates in allantoic fluid from 4 different areas of Nilphamari Districts were detected by slide HA & micro HA tests. Among the 20 isolates, only 2 showed positive by slide HA test. The isolated viruses were further characterized by growing of virus in chicken embryo fibroblasts produced a CPE characterized by a marked granulation of cell cytoplasm, particularly around the nucleus, and further resulted in cell rounding and swelling, followed by fragmentation of cells into small particles and finally cell shrinkage and detachment from the substrate. Primary cultures of chick embryo fibroblasts (CEF) are widely used for the cultivation of viruses. The EDS-76 virus grew well in duck embryo rather than chicken embryo. After experimental infection, the egg production gradually decreases 20-80% as well as laying of soft shelled and shelless eggs were observed 4 days of post infection. Finally it is concluded that EDS 76 virus grew slowly in chicken embryo fibroblasts and produce cytopathic effect that is harmful for the embryo.