Alexander L. Kisch

Dimethyl sulfoxide enhancement of transformation by polyoma virus

Abstract When small amounts of dimethyl sulfoxide (DMSO) are added to cultures of polyoma virus-infected BHK21 cells in fluid medium up to 5 days after infection, significant enhancement of viral transformation is observed. The numbers of both “pure” ( P ) and “mixed” ( M ) transformed colonies that arise are increased. The observed enhancement does not depend on differential selective pressures, on increased viral adsorption, penetration, or on carcinogenicity for cells of DMSO itself. Similar enhancement of transformation was not observed in agar medium. The findings reported suggest that DMSO acts by increasing the likelihood that “physiologically unstable” infected cells will undergo delayed transformation giving rise to either P or M colonies and that the conditions of the agar assay may inhibit the division of “nascent” transformed cells.

The Effect of Chloroquine on Herpesvirus Infection in Vitro and in Vivo

Summary Despite in vitro inhibition by chloroquine of the replication of herpesvirus hominis types 1 and 2 in mouse embryo cell cultures, the course of in vivo infection of newborn mice was unaltered by chloroquine treatment. This discrepancy between in vitro and in vivo results suggest caution in the application of data derived from in vitro assays to the clinical therapy of herpesvirus infection. Plaques produced in BHK-21 cell cultures by HSV-1 and HSV-2 differed in appearance; this difference may prove useful for the presumptive identification of HSV isolates.

Differences in the response of normal and transformed BHK21 cells to dual virus infection: Conditions affecting synergism between vesicular stomatitis virus and newcastle disease virus☆

Abstract Polyoma-transformed BHK21 cells were less sensitive than untransformed BHK21 cells to plaque production by vesicular stomatitis virus (VSV) although neither the adsorption of the input virus to transformed cells nor the burst size were found to be reduced. Infection of either cell type with an avirulent strain (BI) of Newcastle disease virus (NDV) resulted in only a single cycle of noninfectious NDV hemagglutinin production. Neither BHK21 cells nor a polyoma-transformed clonal derivative (Cl-I) produced detectable interferon in response to NDV infection. On the contrary, dual infection with NDV and VSV resulted in a paradoxical enhancement of VSV plaque number and size in Cl-I but not in BHK21 cells. The degree of synergism was affected by the density of Cl-I cell cultures, by NDV multiplicity, and by the time interval between NDV and VSV infection. These findings suggest that alteration of cell functions affecting cellular sensitivity to single (VSV) and also dual (NDV-VSV) infection may be associated with the virus-transformed state.