HOMOLOGOUS INHIBITION, TOXICITY, AND MULTIPLICITY REACTIVATION WITH ULTRAVIOLET-IRRADIATED VACCINIA VIRUS.

Galasso, G. J. (University of North Carolina, Chapel Hill) and D. G. Sharp. Homologous inhibition, toxicity, and multiplicity reactivation with ultraviolet-irradiated vaccinia virus. J. Bacteriol. 85:1309-1314. 1963.-Vaccinia virus whose plaque-forming capacity had been destroyed by ultraviolet rays (2,537 A) was shown to retard the growth of L cells in tube cultures. At input multiplicities (M) of 0 < M < 10, no interference was detected, but at M >== 100 the irradiated virus particles exerted a strong toxic effect on the L cells in monolayer cultures, affecting the plaque formation by active virus which was added. Multiplicity reactivation occurs in sublethally irradiated vaccinia, as shown by virus particle counts via electron microscopy and plaque counts. It is clearly demonstrated in this system because there is no complicating interference. It sets in at a total virus particle multiplicity of about one, even though the multiplicity of the original plaque-forming particles is much below one.