The herpes simplex virus 1 U(S)3 regulates phospholipid synthesis.

Herpes simplex virus type 1 capsids bud at nuclear and Golgi membranes for envelopment by phospholipid bilayers. In the absence of US3, nuclear membranes form multiple folds harboring virions that suggests disturbance in membrane turnover. Therefore, we investigated phospholipid metabolism in cells infected with the US3 deletion mutant R7041(ΔUS3), and quantified membranes involved in viral envelopment. We report that (i) [3H]-choline incorporation into nuclear membranes and cytoplasmic membranes was enhanced peaking at 12 or 20h post inoculation with wild type HSV-1 and R7041(ΔUS3), respectively, (ii) the surface area of nuclear membranes increased until 24h of R7041(ΔUS3) infection forming folds that equaled ∼45% of the nuclear surface, (iii) the surface area of viral envelopes between nuclear membranes equaled ∼2400 R7041(ΔUS3) virions per cell, and (iv) during R7041(ΔUS3) infection, the Golgi complex expanded dramatically. The data indicate that US3 plays a significant role in regulation of membrane biosynthesis.