The antiviral activity exerted by vaccinia virus on the growth of herpes simplex virus in BS-C-1 cells

The growth of herpes simplex virus type 2 (HSV-2) in BS-C-1 cells, was inhi bited following super-infection with vaccinia virus. This inhibition was ef ficiently induced by both the intracellular mature virus (IMV) form of vacc inia virus and the extracellular enveloped virus (EEV), containing an addit ional external viral membrane. Treatment of vaccinia IMV with the detergent s NP-40, Brij-58 or n-octyl-alpha-D-glucopyranoside, abolished its ability to inhibit the growth of HSV-2. Ultraviolet irradiation of vaccinia virus, that completely inactivated the infectivity of the virus, resulted in parti al loss of the capability to inhibit the growth of HSV-2: 16-fold more irra diated virus was needed for the inhibition. Electron microscopy showed that the irradiated vaccinia virus adsorbed and penetrated into the HSV-infecte d cells but remained morphologically intact within the cells for at least 2 2 h. When the steps in the growth of HSV affected by the irradiated vaccini a virus were followed, it was found that while the synthesis of HSV DNA was partially decreased, the synthesis of HSV proteins was very strongly inhib ited and virus particles were not formed. (C) 2000 Elsevier Science B.V. Al l rights reserved.