PVR and infection: To confirm the observation that monospecific murine polyclonal anti-EV-D68 antisera could protect cells in culture from poliovirus type 1/Mahoney infection, murine fibroblasts that produce the human poliovirus receptor (hPVR) were infected with poliovirus type 1/Mahoney that had either been incubated in the presence of sera from wild-type mice or 2-fold serial dilutions of sera from mice immunized with an isolate of EV-D68 from the 2018 outbreak that associated with AFM or from mice immunized with poliovirus type 1/Mahoney.