Effect of different passage histories of infectious bronchitis virus on the sensitivity to inhibitors in chick serum and their removal by trypsin.

Sensitivity of the Beaudette strain of infectious bronchitis virus (IBV) to non-antibody inhibitors in neutralization tests depended on the passage history of the virus. The chick embryo kidney cell-adapted (E71 CEK11) virus was the most sensitive, but after one chick embryo (CE) passage (E71 CEK11 E1), this virus showed reversion to the sensitivity of the parent virus (E71). IBV inhibitors in chicken serum could be removed by treatment with trypsin but not with phospholipase C.