Fig. 4.

NS4A impacts the TOR pathway. (A) The effect of TOR pathway-related gene deletions on NS4A-induced hypertrophy and cellular growth. (a) Cell morphologic changes when NS4A protein was expressed 48 h after GI in wild-type, ∆Tor1, and ∆Tip41 mutant strains. Note that NS4A induced hypertrophy in wild-type cells. However, no apparent gross cell enlargement was seen in the NS4A-expressing ∆Tor1 cells. Conversely, NS4A induced a spherical cell phenotype in the ∆Tip41 mutant strain. (b) Overexpression of the Tip41 gene in the ∆Tip41 mutant strain produced a spherical cell phenotype similar to that shown in a. (Scale bar, 10 μm.) (B) ZIKV NS4A gene transcription by RT-PCR 24 h after GI. (C) The ∆Tor1 deletion suppressed the effect of NS4A on yeast colony formation. (D) ∆Tor1 deletion restored (↑) cellular growth to nearly the normal level in the NS4A-expressing cells; ∆Tip41 worsened NS4A-induced growth inhibition (↓). ●, NS4A gene expressed; ○, NS4A gene suppressed.