AIM:To express all three HCV structural proteins in thepresence or absence of HCV 5’NCR to investigate therequirement of 5’NCR for the assembly of HCV-like particlesin insect cells.METHODS:HCV structural protein encoding sequencesCE1E2 and 5’NCR-CE1E2 were amplified with PCR.Recombinant baculovirus were constructed with recombinantDNA techniques.HCV structural proteins expressed in insectcells were analyzed by immunofluorescence and SDS-PAGE.Immunoprecipitation experiment of insect cell lysates withanti-E2 monoclonal antibody(MAb)was carried out and theimmunoprecipitated proteins were subjected to SDS-PAGEand immunoblotting with anti-C,anti-E2 MAbs and HCVpositive serum.The virus-like particles in insect cells werevisualized by electron microscopy(EM).The HCV-like particleswere purified by sucrose gradient centrifugation andidentified by EM and immune aggregation EM.RESULTS:The recombinant baculovirus reBV/CE1E2containing HCV C,E1,E2 genes and reBV/CS containingthe same structural protein genes plus 5’NCR wereconstructed.The insect cells infected with either reBV/CE1E2or reBV/CS expressed HCV C,E1 and E2 proteins with amolecular weight of 20 kD,35 kD and 66 kD respectively.The results of immunoprecipitation and the immunoblottingrevealed the coimmunoprecipitation of C,E1,and E2proteins,indicating the interaction of HCV structuralproteins expressed in insect cells.Electron microscopy ofinsect cells infected with reBV/CE1E2 or reBV/CSdemonstrated spherical particles(40 to 60 nm in diameter)similar to the HCV virions from sera or hepatic tissues ofHCV infected humans.The HCV-like particles were partiallypurified by sucrose gradient centrifugation,and thepurified VLPs showed immuno-reactivity with anti-HCVantibodies.CONCLUSION:HCV 5’NCR is not required for the assemblyof HCV-like particles in insect cells,HCV core and envelopeproteins are sufficient for viral particle formation. AIM: To express all three HCV structural proteins in the presence or absence of HCV 5 ’NCR to investigate therequire of 5’ NCR for the assembly of HCV-like particles in insect cells. METHODS: HCV structural protein encoding sequences CE1E2 and 5 ’NCR-CE1E2 were amplified with PCR. Recombinant baculovirus were constructed with recombinant DNA techniques. HCV structural proteins expressed in insect cells were analyzed by immunofluorescence and SDS-PAGE. Immunoprecipitation experiment of insect cell lysates withanti-E2 monoclonal antibody (MAb) was carried out and the immunoprecipitated proteins were subjected to SDS-PAGE and immunoblotting with anti-C, anti-E2 MAbs and HCVpositive serum. The virus-like particles in insect cells were visualized by electron microscopy (EM). The HCV-like particles were purified by sucrose gradient centrifugation andidentified by EM and immune aggregation EM .RESULTS: The recombinant baculovirus reBV / CE1E2containing HCV C, E1, E2 genes and reBV / CS containing the same structural prot ein genes plus 5’NCR were con-structed. The insect cells infected with either reBV / CE1E2or reBV / CS expressed HCV C, E1 and E2 proteins with amolecular weight of 20 kD, 35 kD and 66 kD respectively.The results of immunoprecipitation and the immunoblottingrevealed the coimmunoprecipitation of C, E1, and E2 proteins, indicating the interaction of HCV structural proteins expressed in insect cells. Electron microscopy of insect cells infected with reBV / CE1E2 or reBV / CS demonstratedmonstrated spherical particles (40 to 60 nm in diameter) or hepatic tissues of HCV infected humans. The HCV-like particles were partially purified by sucrose gradient centrifugation, and thepurified VLPs showed immuno-reactivity with anti-HCVantibodies. CONCLUSION: HCV 5’NCR is not required for the assembly of HCV-like particles in insect cells , HCV core and envelope proteins are sufficient for viral particle formation.