Under certain conditions, influenza virus may bind to chorioallantoic membrane and the infectious property is retained upon prolonged incubation of the complex. Apparently the bound active virus is not functioning in the initiation of viral increase.
The bound infectious virus may be partially removed by extensive washing. The characteristics of the washing are suggestive of a reversible equilibrium type of binding. Binding will also occur when the tissue has been pretreated with RDE or in the presence of AMPS. However, under these conditions the binding is of a lesser degree. When the tissue has been treated with RDE and AMPS is present, no stable binding occurs. In the presence of AMPS, the initiating activity is bound but cannot function in promoting viral increase.
It is proposed that active virus is held by two types of binding at the same site; one type of binding is sensitive to the action of RDE; the second type is sensitive to the blocking effect of AMPS. Virus can be held to the receptor site by either type of binding or both. It is further suggested that the bound infectious virus is a result of an abortive attempt at initiating infection. The nature of the binding of infectious virus is of significance for understanding the binding of initiating activity.