Abstract: A method for identifying a candidate agent for affecting a viral infection is described. The method comprises (a) providing a first component comprising a signal peptide peptidase targeting sequence; (b) providing a second component comprising a signal peptide peptidase as a second component; (c) contacting the two components with an agent to be tested under conditions that would permit the two components to interact in the absence of the agent; and (d) determining whether the agent disrupts the interaction between the first and second components. Preferably the signal peptide peptidase targeting sequence is derivable from hepatitis C virus (HCV) core protein or a derivative, variant or homologue thereof.