One strain of infectious bovine rhiontracheitis was isolated from calves with respiratory disease in bovine kidney cell cultures, and purified by plaque forming method. The virus replication was inhibited in the present of 5-iodo 一2'-deoxyuridine. It was stable at PH 7 to 8, but loses activity below PH5, It was inactivated by exposure at 56 °C for 30', and at 60°C for 15', and destroyed by treatment of I M, MgCl, at 50°C, for 30'.
The isolated virus was serologically related to the cooper strain of infectious bovine rhinotracheitis, It did not agglutinate bovine, goat and sheep red blood cell at 4°C. The precipitin line appeared when anti-lBR-C rabbit serum wasalllow to diffuse toward the isolated virus, but anti-BVD-NADL or anti-Pl,-SF-4 rabbit serum did not react to the isolated virus.
The isolated virus produced cytopathic effect in BT, BK, AuBEK, ESK, PK-15, and HeLa cell cultures.