Abstract
Recombinant baculovirus expression system has been widely used in protein production, gene therapy and vaccine development. In applications, the dose of baculovirus is determined by virus titers. However, the common method for baculovirus titration TCID50 which cost is lower than other method, but this is a time-consuming and difficult to be determined. Thus, we would like to develop a fast and accurate method for baculovirus titration. We successfully establish a Sf-9ET cell lines for baculovirus titration via G418 screening. Sf-9ET cell lines contain the polyhedrin promoter-green fluorescent protein expression cassette. While Sf-9ET cell lines infected by baculovirus, baculovirus will drive the polyhedrin promoter and express green fluorescent protein. We using Sf-9ET for baculovirus titration, we found that the fluorescence observed at 7 dpi (days post-infection) and cell cytopathic effect observed at 11 dpi, both obtained similar baculovirus titer respectively. Then, we use the baculovirus Bac-Polh-DsRed which express red fluorescent protein in infected Sf-9ET cells, the results show the red and green fluorescence observed at same time, we obtained same titer of the baculovirus. Thus, Sf-9ET cell line is accurate for baculovirus titration. Several type of baculovirus titer obtained by Sf-9ET which are similar to original baculovirus titration method. Sf-9ET cell line is universal for all baculovirus for titration. Finally, we demonstrate that Sf-9ET cells were subcultured to P50 still retains the sensitivity of titration. In summary, this study established Sf-9ET cell line can significantly shorten the time for titration and easy to determine. Sf-9ET cell line is accurate and stable.