[Physicochemical characteristics of an influenza virus population inactivated by gamma rays]. / Fiziko-khimicheskaia kharakteristika populiatsii virusa grippa, inaktivirovannogo gamma-luchami.

A study was made of the effect of 60Co-gamma-radiation on the integrity of particles of the influenza virus and on the structure of some of its proteins. The physicochemical changes in virions were shown to depend upon radiation conditions. A conclusion is made that it is possible to use gamma-rays in the production of a centrifuged virion influenza vaccine.

[Persistent influenza virus infection. Molecular genetic characteristics of ts mutants selected during persistence]. / Persistentnaia infektsiia virusa grippa. Molekuliarno-geneticheskaia kharakteristika ts-mutantov, selektsioniruiushchikhsia v protsesse persistentsii.

Properties of ts mutants isolated from systems of persistent influenza infection formed in MDCK cell culture by A/Victoria/35/72 virus were studied. The ts mutants isolated at later intervals of persistent infection (158 days) were characterized by thermolability of hemagglutinin and neuraminidase, changes in the EP mobility of HA2 polypeptide, decrease in the molecular weight of this polypeptide, appearance of multiple ts mutations in genes 3, 5, 6, 7, and 8, coding for P2, NP, NA, M, and NS proteins, respectively.

[Changes in the genetic properties of a viral population and the selection of ts-mutants in persistent influenza virus infection]. / Izmenenie geneticheskikh svoistv virusnoi populiatsii i selektsiia ts-mutantov pri persistentnoi infektsii virusa grippa.

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.

[Persistent influenza virus infection in a MDCK cell culture]. / Persistentnaia infektsiia virusa grippa v kul'ture kletok MDCK.

A model of persistent influenza infection (PII) induced by influenza A/Victoria/35/72 (H3N2) virus in MDCK cell culture has been constructed. The model was observed for 165 days. It was characterized by the lack of visible signs of virus reproduction, a low number of antigen-containing cells (0.02-0.05%), irregular virus isolation (at 20, 28, 32, 44, 52, 62, 92, 135, 148, 158 days after primary inoculation) which was possible only with special methods. Interferon and DIP were found not to be the factors responsible for maintenance of PII in MDCK culture.