The F (frameshift) protein or ARFP (alternate reading frame protein) is generated as a result of a -2/+1 ribosomal frameshift in the N-terminal core-encoding region of the HCV polyprotein. Antibodies to peptides from the F protein were detected in chronically infected patients, suggesting that the protein is produced during infection. However, the exact translational mechanisms governing the frequency and yield of the F protein during the various phases of HCV infection are completely unknown. Thus the role of F protein in the HCV lifecycle remains enigmatic, but it has been postulated that the protein contributes to viral persistence.