Porcine IL-12 plasmid as an adjuvant improves the cellular and humoral immune responses of DNA vaccine targeting transmissible gastroenteritis virus spike gene in a mouse model

LI, Xunliang; LI, Pengchong; CAO, Liyan; BAI, Yunyun; CHEN, Huijie; LIU, He; REN, Xiaofeng; LI, Guangxing

In vitro expression of pVAX1-(TGEV-S1) and pVAX1-(pIL- 12) All assays were performed using the previously described methods [13, 19] with some modifications. pVAX1-(TGEV-S1), pVAX1-(pIL-12), and pVAX1 were resuspended in 0.1 M phosphate-buffered saline (PBS) at a concentration of 1 µg/µl, and 1 µl of each plasmid was transfected with Lipofectamine 2000 (Invitrogen) into BHK-21 cells at about 90% confluence. The cells were cultured at 37°C for about 24 hr, fixed with 4% (w/v) paraformaldehyde, and incubated with anti-TGEV-S1 or anti-pIL-12 (p40) antibody (1:200 diluted in 1% bovine serum albumin [BSA]). The samples were incubated in the dark with a fluorescein isothiocyanate (FITC)-labeled secondary antibody (1:200 dilution with 1% BSA). The green fluorescence signals were detected using a fluorescence microscope (Leica, Wetzlar, Germany).