The multiplication of vaccinia virus in suspended KB cells

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.

Occluded and nonoccluded nuclear polyhedrosis virus grown in Trichoplusia ni: comparative neutralization comparative infectivity, and in vitro growth studies

Nuclear polyhedrosis virus infections of lepidopteran cells often result in the production of both occluded and nonoccluded virus. The characterization of these two different forms has been the subject of several papers. We have divided the nonoccluded virus (NOV) category further into plasma membrane-budded non-occluded virus (PMB-NOV), intracellular NOV, and hemolymph-derived NOV, and have done additional studies investigating the differences between these nonoccluded forms and the alkali-liberated forms from occlusions of the nuclear polyhedrosis viruses of Autographa californica and Rachiplusa ou. The methods used to discern differences and similarities among the forms were serological, biochemical, and visual, all related to their biological acitivity. Neutralization studies revealed that alkali-liberated virus and PMB-NOV had both similar and different antigens. Antisera raised against alkali-liberated virus from occlusions neutralized the alkali-liberated form of the virus, but did not neutralize the intracellular or extracellular nonoccluded forms. Antisera raised against the TN-368-13 PMB-NOV, however, neutralized the alkali-liberated forms as well as all forms of the NOV. Adsorption of this antisera with alkali-liberated virus did not diminish the neutralization titer against the nonoccluded forms, thus confirming the antigenic differences between the alkali-liberated and nonoccluded forms of the virus. Physical-infectious particle ratio calculations indicated that the PMB-NOV of Autographa californica are about 1,900-fold more infectious than the single-nucleocapsid-per-envelope alkali-liberated particles and about 1,700-fold more infectious than the multiple-nucleocapsid-per-envelope particles, as assayed in vitro. In addition, a study of viral growth kinetics monitored concurrently with the appearance of polyhedra showed that PMB-NOV production is shut down with the onset of polyhedron formation.