| Abstract: | The hemagglutinating (HA) activity of 14 strains of infectious bronchitis virus (IBV) was investigated. The optimal conditions for IBV antigen preparation include inoculation of 10- or 11-day-old specific pathogen-free embryonated eggs and incubation for 30 hours at 37 C. Embryos were inoculated via the allantoic cavity with 0.1 ml of a low embryonic passage of the virus (10(7) to 10(8) EID50/ml). Allantoic fluid was harvested and pooled, and a 100-fold concentration of virus particles was achieved by centrifugation for 3 hours at 30,000 x g. Virus pellets were resuspended in Tris-hydrochloride buffer containing 3 units of phospholipase-C (type-1) enzyme/ml and incubated for 2 hours at 37 C. All IBV strains tested demonstrated positive HA activity with chicken red blood cells. The antigen was stored in liquid state or lyophilized at 4 C. |
