[Changes in the genetic properties of a viral population and the selection of ts-mutants in persistent influenza virus infection].

Comparative study of genetic properties of the original influenza A/Victoria/35/72 virus (the inhibitor-sensitive variant) and persisting viruses (PV) isolated at different intervals (from 9 to 158 days) after infection with this virus of MDCK cell culture revealed that in the course of development of persistent infection (PI) there occurred progressive selection of temperature-sensitive (ts) mutants. In parallel with this, changes in the profile of PV inhibitor-sensitivity and plaque phenotype were noted. A population of PV isolated at late intervals (158 days) consisted completely of temperature-sensitive, inhibitor-resistant, small-plaque clones. According to the results of HI tests, the antigenic characteristics of PV hemagglutinin did not differ from those of the original virus. The mechanisms of development of the described persistent infection are discussed.