A Y45F mutation in hepatitis C virus NS4A causes a decrease in infectious viral titer.

(A) Schematic of the NS4A protein. * indicates location of Y45F mutation. Numbers correspond with the amino acid position within NS4A (aa 1–54) or the full-length polyprotein (aa 1690–1711). Strain names are listed as found in the Los Alamos HCV sequence database. (B) Focus forming assay of supernatants harvested from Huh7.5 cells at the indicated days post-electroporation with HCV WT or NS4A Y45F in vitro transcribed RNA. FFU/mL = focus forming units/milliliter. Values are presented as mean ± SD (n = 3). Data are representative of three independent experiments. N.D. = not detected. L.D. = limit of detection. (C) Sequencing of the NS4A region (nt 4710–5251) of cDNA amplified from Huh7.5 cells transfected with HCV WT or NS4A Y45F RNA (JFH1) in (B) at indicated days.