Abstract: Objective To find out the physical state of the human papillomavirus (HPV) genome in hepatoma cell line Hep G2 cells and the regularity of HPV late capsid protein 1 (L1) expression and to explore the nature of the cytoryctes in Hep G2 cells. Methods: E2 and E6 in HPV18 were detected by PCR to evaluate the physical state of HPV18 genome. Hep G2 L1 expression was detected by ELISA, light microscrope and electron microscrope immunohistochemistry assays, Western blot assay using HPV L1 mice monoclonal antibody. L1 mRNA in Hep G2 cells was detected by reverse transcriptional PCR (RT-PCR). Results: PCR assay displayed that HPV DNA was integrated with Hep G2 genome. ELISA assay showed that HPV L1 was present in lysate of Hep G2 cells. Light microscrope demonstrated strong positive reaction in Hep G2 cells. Observed under electron microscopy, in the cytoplasm of partial Hep G2 cells, there were lumpish cytorrhyctes materials which were composition by very small and uniform particles and these particles could be marked by HPV L1 antibody which was labeled by colloidal gold. Western blot analysis showed a band at 56ku district and it was L1 specific strap which demonstrated HPV18 L1 was present in Hep G2 cells. RT-PCR assay demonstrated the presentation of L1mRNA in Hep G2 cells. Conclusion: Hep G2 cells are HPV18-positive cells, HPV DNA genome is integrated with Hep G2 cells. Hep G2 cells can express L1. The cytorrhyctes in Hep G2 cells are composed of HPV18 L1 indicating that L1 can be expressed in Hep G2.

Key words: Hep G2 cells, human papillomavirus, virus genome, physical state, late capsid protein 1