Excess of interfering over infectious particles in herpes simplex virus passaged at high m.o.i. and their effect on single-cell survival.

The capacity of herpes simplex virus to kill cells and to form both infectious centres and progeny virus was studied in cell culture. Two virus stocks were compared at various m.o.i.: (i) a standard virus stock and (ii) a stock which contained interfering virus particles (I particles). The formation of infectious progeny virus as well as of infectious centres appeared to be reduced by the action of I particles. In the examined virus stock I particles exceeded infectious particles by at least a factor of 5 to 10. More than 50% of cells which could be demonstrated to be hit by I particles survived and formed colonies.