Ultra low igg foetal bovine serum

Exponential growth-phase adherent HEK293 cells were re-suspended in DMEM (Sigma-Aldrich) supplemented with 2 mM L-glutamine, 100 U/mL penicillin, 1 mM sodium pyruvate, 0.1 mg/mL streptomycin and 10 % ultra-low IgG foetal bovine serum (FBS) (Thermo Fischer Scientific) and seeded at 4 x 10⁴ cells/well in 100 μL 24 h prior to transfection in Costar 96-well cell culture plates (Corning). On the day of transfection, for each well, 50 μL of 60 μg/mL linear 25 kDa PEI (Alfa Aesar) was mixed with 200 ng of cognate heavy- and light-chain coding plasmid in a volume of 50 μL and shaken at 20°C for 30 min. The DNA-PEI complexes were added to the HEK293 cells. The following day, an additional 50 μL of supplemented DMEM (as described above) was added to each well. Supernatants were screened for PvDBPII (produced in S2 cells as described below) binding by indirect ELISA. Over 100 mAb supernatants were screened in this assay and of these, ten bound PvDBPII.