Optimization of conditions for expressing recombinant HPV11 L1 protein in sf 9 insect cells

Objective To select the optimum conditions for amplification and expression of the recombinant human papillomavirus 58 (HPV58) LI gene using baculovirus-insect cell expression system. Methods The Sf9 insect cells at logarithmic phase was used to amplify virus at different multiplicities of infection (MOI). Titers of the virus were determined by plaque assay. The expression of recombinant protein was identified by indirect immunofluorescence assay, and the expression of recombinant protein at different MOI and time was determined by Western blot. Results Recombinant baculovirus containing HPV58 LI gene were amplified at MOI of 0.5 for 48 h when the Sf9 insect cells were at logarithmic phase, and the highest titers of the virus reached 5×108 pfu/ml. The optimum conditions for expressing the recombinant protein were that the recombinant baculovirus was inoculated at MOI of 5.0 and the protein was expressed within 72 h. Conclusion The optimum conditions for amplifying the virus and expressing the recombinant protein are determined. Key words: Human papillomavirus; Gene expression; Recombinant proteins