Demonstration of Influenza Virus, Type B, in a Recent Outbreak of Upper Respiratory Infection

Abstract

A strain of influenza B virus was isolated in May, 1945, from an outbreak of upper resp. infection at Camp Atterbury, Indiana. The virus was detected in the 2d egg passage done by the method of Hirst. The identity of the virus was established by the red blood cell agglutination-inhibition test, using sera from chickens immunized against Type A (PR8) and Type B (Lee) viruses. The new strain was named "Saha." It was antigenically related to the Lee virus, and it had no common antigen with Type A virus. It was passed 9 times to date in chick embryos by the allantoic route. Serol. tests on patients afforded more evidence that the outbreak was due to a Type B virus.