[Study of formation of amantidine and rimantidine resistant variants of influenza A2 subtype virus].

Passages of influenza A2/Hong Kong/68 in developing chick embryos in the presence of amantadine and rimantadine were carried out and demonstrated rapid development of a resistant virus line under these conditions. Changes in the sensitivity of the virus to the drug were due to selection of resistant particles from genetically inhomogenous original virus strain. The rate of formation of the resistant population was shown to be clearly dependent upon the amount of amantadine inoculated into embryos. The resulting resistant lines retained this property throughout multiple virus passages in embryos without the drug. These biological and antigenic properties of the resulting variants did not differ from those of the initial A2/Hong Kong/68 strain.