Down-regulation of CD81 in human cells producing HCV-E1/E2 retroVLPs

Background Retroviral based biopharmaceuticals are used in numerous therapeutic applications, from gene therapy to vaccination [1-3]. Nonetheless, retroviruses are known to incorporate proteins from the host cell which may increase the vector immunotoxicity [4]. CD81, a membrane protein belonging to the tetraspanin superfamily has been recently identified as one of the host cell proteins majorly incorporated into Moloney Murine Leukemia Virus (MoMLV) derived vectors[5]. Therefore, CD81 was chosen as a target for studying the effects of host cell protein incorporation in the immunotoxic profile of retroviral vectors (RV). A human cell line, 293rVLP, producing retrovirus like particles (rVLPs) was used to prove the concept of customizing RV composition by manipulating cellular protein content, using the CD81 tetraspanin as a case study. rVLPs will be used as candidate vaccines for hepatitis C by displaying HCVE1/E2 proteins.