Recombinant baculovirus titration by Cell Size Assay (CSA)
In this work, we exploited an easy and fast method for baculovirus titration based on cell size Assay (CSA) which was reported in literature (Janakiraman et al., 2006). This method is based on the measurement of infected viable cells diameter. Briefly, dilutions were prepared in a 48-well plate as following: 48µl of the virus stock was added to 252µl of Sf-900 III SFM and seven additional 1:2 serial dilutions were realized adding 150µl of the previous dilution to 150µl of medium. A volume of 875µl of Sf9 cell suspension at 1.15x106 cells/ml were dispensed into each well of a 24-wells low-attachment plate and completed with 125µl of each dilution. An uninfected control and a concentrated control were also prepared by adding 125µl of medium or 125µl of the undiluted virus stock, respectively. The plate was immediately placed at 27°C under shaking at 175 rpm for 17 to 20h. After incubation, the cell diameter was measured for each dilution using a Vi-CELL counter (Beckman Coulter, CA).