Synthesis of a novel hepatitis C virus protein by ribosomal frameshift

Xu, Zhenming; Choi, Jinah; Yen, T.S.Benedict; Lu, Wen; Strohecker, Anne; Govindarajan, Sugantha; Chien, David; Selby, Mark J.; Ou, Jing‐hsiung

Hepatitis C virus (HCV) is an important human pathogen that affects ∼100 million people worldwide. Its RNA genome codes for a polyprotein, which is cleaved by viral and cellular proteases to produce at least 10 mature viral protein products. We report here the discovery of a novel HCV protein synthesized by ribosomal frameshift. This protein, which we named the F protein, is synthesized from the initiation codon of the polyprotein sequence followed by ribosomal frameshift into the −2/+1 reading frame. This ribosomal frameshift requires only codons 8–14 of the core protein‐coding sequence, and the shift junction is located at or near codon 11. An F protein analog synthesized in vitro reacted with the sera of HCV patients but not with the sera of hepatitis B patients, indicating the expression of the F protein during natural HCV infection. This unexpected finding may open new avenues for the development of anti‐HCV drugs.