CHO-K1 cell-derived scFv targeting pseudorabies virus ameliorates multi-organ viremia and improves animal survival in a lethal infection model.

The pseudorabies virus, with enhanced virulence, increased transmissibility, and severe co-infections, have re-emerged worldwide, leading to significant economic losses in swine industry. However, the traditional Bartha-K61 vaccine could not provide full protection against the PRV variant strains, thus, an urgent need for the development of novel prophylactic and therapeutic strategies. Here, we proposed a novel antibody construct, PRV single chain fragment variable (PRV-scFv), for PRV antibody therapy. The PRV-scFv genes were constructed by joining the PRV-VH and PRV-VL sequences, isolated from the immunized mice's spleen, via a flexible (Gly4Ser)3 linker. This construct was stably expressed in CHO-K1 cells cultured in serum-free suspension. Based on these findings, we screened a monoclonal cell line, CHO-K1-PRV-scFv-2E8 cell, to robustly express PRV-scFv antibody that effectively inhibited PRV infection in vitro, reduced the viral load in vivo, and improved the survival rate of infected mice, which provided new insights into antibody therapy and veterinary therapeutic strategies development.