coli as soluble in the cell lysate following IPTG induction. For preparation of immunogen, the soluble NS1 was purified by Amylose Resin according to pMAL™ Protein Fusion and Purification System, Version 5.01 (New England Biolabs, Inc., USA). Purified NS1 was used for immunization. Hybridoma cells secreting anti-NS1 antibodies were generated according to standard procedures [45]. Briefly, six-week-old female BALB/c mice were immunized subcutaneously with purified NS1 emulsified see more with an equal volume of Freund’s complete adjuvant (Sigma, St. Louis, MO, USA). Two booster injections containing purified NS1 with equal volume of Freund’s incomplete

adjuvant were given at 2-week intervals. The final immunization, purified NS1 without adjuvant was given intraperitoneally. Three days after the

final dose, mice were euthanized and spleen cells were Pirfenidone supplier harvested and fused with SP2/0 myeloma cells at 5-10:1 ratio using polyethylene glycol (PEG 4000, Sigma). Hybridoma cells were seeded into 96-well plates and selected in HAT medium (DMEM containing 20% fetal bovine serum, 100 ug ml-1 streptomycin, 100 IU ml-1 penicillin, 100 mM hypoxanthine, 16 mM thymidine and 400 mM aminopterin), and after 5 days, the medium was removed and replaced with fresh HT-DMEM medium. After HAT/HT selection, culture supernatants of surviving clones were screened for reactivity and specificity by indirect ELISA, WB and IFA. The ELISA was described previously [46]. Briefly, microplates were sensitized learn more at 4°C overnight with affinity-purified WNV-NS1 antigen at 100 ng ml-1. The sensitized plates were incubated with culture supernatants from hybridoma cells at 37°C for 1 h, with HRP-conjugated goat anti-mouse secondary antibodies (LICOR Biosciences) at a 1:4,000 dilution at 37°C for 1 h, followed

by color development with substrate solution containing o-phenylenediamine (OPD). WB was performed as described above, but the primary antibodies were the mAbs supernatant and HRP-conjugated goat anti-mouse secondary antibodies were used. The IFA results were supplied by Beijing Institute of Microbiology and Epidemiology. WNV, JEV, DENV1-4, YFV and TBEV antigen slides were prepared on porous slides using WNV, JEV, DENV1-4, YFV and TBEV infected and uninfected C6/36 cells. Cell suspensions were dripped onto slides, fixed using acetone, air dried and stored at -20°C. Next, anti-NS1 mAbs supernatant and WNV-, JEV-, DENV1-4-, YFV- and TBEV-positive/negative mouse sera (working dilution was 1:100) (positive/negative control) were incubated on acetone-fixed antigen slides for 2 h. A FITC-conjugated goat anti-mouse IgG (Sigma, USA) was used as a secondary antibody at a 1:50 dilution, and slides were viewed at a magnification of ×40 on a fluorescence microscope (Leica, Germany) [47]. The positive cell clones were subcloned three times by limiting dilution method.