[The phenomenon of transition of filamentous virions of influenza viruses into spherical virions].

A type of transition of filamentous influenza A virus virions into spherical ones differing from fragmentation is described. The transition occurs through the formation of racket-like particles. Such transitions may be initiated by deformations occurring in filamentous virions upon storage. The stability of filamentous virions depends greatly upon the ionic strength of the solution. The main regularities of this process are described. A possible mechanism of formation of filamentous virions and the factors determining their stability are discussed.