mAb41 pages the E2-CD81 interaction. CD81-Fc was captured on protein G magnetic beads and then incubated with E2-FLAG, with or without mAb41, Fab41, or Fab41 complexed with either epitope II or the epitope II mimic peptide. An IGIV which lacks any detectable anti-HCV activity was used as a negative control. Proteins bound on the beads were eluted, separated by SDS-PAGE under reducing conditions, and probed with either anti-Fc or mAb41.