Multiplicity reactivation of vaccinia virus particles treated with nitrogen mustard

Scrapie infectious agent is virus-like in size and susceptibility to inactivation

The virions of all known viruses are composed of small amounts of genomic nucleic acid enveloped by proteins and other macromolecules. The aetiological agents of scrapie disease and the other subacute spongiform virus encephalopathies (SSVE), a group of slow, fatal degenerative diseases of the central nervous system, are, based on their resistance to sterilization and on indirect measurements suggesting subviral size, thought to have non-viral structures (see refs 1-3 for reviews). The kinetic studies reported here demonstrate that scrapie's resistance to many inactivants is limited to small subpopulations of the total infectivity, the majority population being highly sensitive to inactivation. Moreover, control inactivations of conventional viruses provide examples of both scrapie-like resistant subpopulations and complete insensitivity to virucidal agents, especially when those viruses, like scrapie, are suspended in hamster brain homogenate. Virus controls further establish that the ability of the scrapie agent to penetrate dilute agarose-acrylamide electrophoretic gels is shared by conventional viruses. Direct comparison of scrapie's resistance to ionizing radiation with the resistances of other viruses places scrapie with the smaller viruses, as opposed to requiring a subviral size as claimed.

Partial reactivation of chlorine-treated echovirus

After treatment of a dispersed suspension of echovirus with HOCl, much of the lost plaque titer was restored if the treated virus was induced to aggregate by adjustment of the suspending medium to pH 4.5. This did not appear to be a repair of individual virions but rather a special kind of multiplicity-related increase in plaquing efficiency which occurred when the host cell received several of the damaged virions in a clump.

Target volume analysis of vaccinia virus: influence of virus dispersion and noninfectious particles

These data indicate that 90% of monodisperse vaccinia virus (VV) has a D(37) dose of 1.0 x 10(4) +/- 0.2 x 10(4) rad when exposed to the direct effect of gamma radiation from (137)Cs and (60)Co sources. This D(37) dose yielded a targt size of approximately 10(8) daltons, close to the molecular weight of VV deoxyribonucleic acid. This target corresponds to the first component of the survival curve of VV. Noninfectious virus seemed to play a role on the slope and the proportion of the survival curve second component, suggesting that multiplicity reactivation takes place.