Direct Relationship between Protein Expression and Progeny Yield of Herpes Simplex Virus 1 Unveils a Rate-limiting Step for Virus Production

Although viral protein expression and progeny virus production were independently shown to be highly heterogenous in individual cells, their direct relationship, analyzed by considering their heterogeneities, has not been investigated to date. This study established a system to fractionate cells infected with a herpesvirus based on the levels of the global expression of viral late proteins, which are largely virion structural proteins, and to titrate virus yields in these fractions. This system demonstrated a direct relationship and indicated there was a threshold for the levels of viral late protein expression for progeny virus production and that viral DNA cleavage/packaging was a rate-limiting step for progeny virus production. These findings, which were masked in previous studies performed at the entire population level, have uncovered a sophisticated viral strategy for efficient progeny virus production and shed new light on an effective target for the development of anti-viral drugs.