Expression of vaccinia virion surface tubule protein as a virus specific cell surface antigen.

The sequential expression of a vaccinia virus specific antigen on the surface of infected cells has been followed by 125I-labelled anti-vaccinia IgG. After an initial drop (during the first 30 minutes of infection) the amount of viral antigen at the cell surface increased steadily for the 12 hours tested. The expression of the antigen was found to depend on protein and RNA synthesis from the start, but dependent on DNA synthesis only after 4 hours. The senitivity of the phenomenon to ultraviolet light irradiation of the virus suggests that the genetic information needed for the expression of the antigen resides in the viral genome. The antigen has been identified as the virion surface tubule, a tubule-like structure on the surface of the intact virion. It is known that vaccinia virus infection of cells starts with the fusion of the virion envelope with the host plasma membrane. It is here proposed that initially tubule from input virus is detected as viral antigen on the cell surface. Subsequently, virus tubule protein synthesised de novo migrates and is detectable as the virus specific cell surface antigen.