Figure 1.

Construction and characterization of recombinant border disease virus (BDV) carrying high-affinity NanoBiT (HiBiT). (A) Schematic diagram of the BDV cDNA clone encoding the HiBiT luciferase gene. Amino acid sequence of HiBiT (red) and linker (green) was inserted upstream of E^rns of BDV FNK2012-1 strain (indicated by arrow). (B) Swine kidney line-L (SK-L) cells were infected with 200 50% tissue-culture infective doses (TCID₅₀) of BDV FNK-WT (WT) and the recombinant vBDV FNK/HiBiT P2 (vBDV/HiBiT P2). Infectious titers in the culture supernatant were determined at the indicated time points. Data are presented as mean ± standard error (SE) (n = 3). Asterisks indicate significant differences (*, p < 0.05) versus the result of the vBDV/HiBiT P2. (C) SK-L cells were infected with 200 TCID₅₀ of vBDV FNK/HiBiT, then the recombinant BDV was passaged five times. Undiluted culture supernatant (100 µL) at 3 days post-infection (dpi) was used for the next passage in naïve cells, and infectious titers in the culture supernatant were determined at 4 dpi after each passage. (D) SK-L cells were infected with 200 TCID₅₀ of vBDV FNK/HiBiT, then the recombinant BDV was passaged five times. Luciferase activity in the cells was determined at 4 dpi after each passage. Data are presented as mean ± standard error (SE) (n = 3). Asterisks indicate significant differences (*, p < 0.05) versus the result of the vBDV FNK/HiBiT P0.