Effect of routes of inoculation on yield of R_2B strain of new castle disease virus

摘要

Newcastle disease, also known as Ranikhet disease of poultry has been seen in India since 1928 (Cooper, 1930) but inspite of availability of good quality vaccines, it still remains an unresolved problem particularly in Asian subcontinent (Alexander,1997). Lots of studies have been done in the past on the cultivation of the virus in developing chicken embryos (DCE) as well as in cell cultures. Cell cultures, although are more convenient medium to get the virus in bulk, but they yield poor titer ofvirus in case of NDV (Buxton and Fraser, 1977, Velan et al. 1995). Hence, an attempt was made to study the growth behavior and yield of R_2B strain of Newcastle disease virus following inoculation via chorioallantoic membrane (CAM) route and allantoic cavity route. Two groups of 9-11 days old developing chicken embryos were inoculated with 0.1 ml of virus suspension by CAM and allantoic cavity route as per the method described by Hanson (1975). All the inoculated eggs were incubated at 37 deg C and candled daily at an interval of 8h. Those found dead were dept in refrigerator at 4 deg C. The process wqas continued upto 48h or when all the inoculated embryos died. Thereafter, the chorioallantoic membrane and allantoic fluid were harvested separately from all the inoculated eggs and haemagglutination (HA) titres were determined using 1.0 percent fowl erythrocytes as per the method of Allan et al., (1978). DCE inoculated via chorioallantoic route revealed high HA titre initially in CAM (5 log_2) upto 16hrs. But later, the virus titers decreased markedly in CAM (3 log_2) at 32h PI (Table-1). Whereas, the DCE inoculated via allantoic route showed gradual increase in HA titer in CAM(4 log_2) as well as in allantoic fluid (12 10g_2) upto 24h PI but the titer remained always high in allantoic fluid. After 32h PI, the HA titer decreased in both of the systems (Table-1) inoculated by allantoic route.