Development of resistance to 2-(1-amino-ethyl)-bicyclo (2.2.1) heptane chlorohydrate in influenza A virus

A resistant influenza virus has been obtained during successive passages of influenza A virus in 10 to 11-day-old chick embryos (CE) in the presence of 2-(1'-amino-ethyl)-bicyclo(2.2.1) heptane chlorohydrate possessing a high antiviral activity. The virus resistance to the inhibitor was not lost after one passage in the absence of the drug.