Porcine CD161 promotes Japanese encephalitis virus entry: a potential host-directed antiviral target.

Japanese encephalitis virus (JEV) remains a major global zoonotic threat to both animal and human health. Viral attachment to host cells is an early and targetable step in infection. Here, we investigated the role of the C-type lectin-like receptor CD161 (encoded by Killer cell lectin-like receptor B1, KLRB1) in JEV infection using PK15 cells. The stable CD161-knockout PK15 cell lines (PK15-K.O.) and CD161-overexpressing PK15 cell lines (PK15-O.E.) were generated using CRISPR/Cas9 genome editing and lentiviral transduction, respectively. Following JEV infection, PK15-K.O. cells showed markedly reduced viral titer, intracellular viral RNA levels, and JEV envelope (E) protein expression. Conversely, PK15-O.E. showed increases in all these viral indicators. Further analyses revealed that CD161 functions during the early entry stage, promoting both viral attachment and subsequent internalization. Taken together, these findings firstly identify porcine CD161 as a key host factor that facilitates JEV entry into PK15 cells, suggesting that CD161 is a potential host-directed antiviral target.