Vaccinia virus cytotoxin(s)

Abstract

THE mechanisms whereby cytopathic viruses damage or kill susceptible cells are not fully understood. Some experiments with pox viruses involving partially inactivated virus or various metabolic inhibitors suggest a correlation between the production of virus proteins and the appearance of cytopathic effects without necessarily establishing a casual relationship between the two events^1,2. Other work suggests that inhibition of host protein synthesis, and by extension induction of cytopathic effects by vaccinia virus, is independent of virus-induced protein synthesis but is some function of the virus particle itself³. Here, we report direct experiments in which vaccinia-specific materials were isolated from infected HeLa cells, rendered free from infective virus and shown to be toxic to susceptible uninfected HeLa cells under appropriate test conditions. To our knowledge this is the first documented example of an observable cell-killing effect of vaccinia specific protein(s). It differs from that of the penton capsomere (toxin) of adenovirus which affects cell membranes from the outside causing them to detach from glass⁴, in that we believe it acts intracellularly.