Characterization of classical swine fever virus entry by using pseudotyped viruses: E1 and E2 are sufficient to mediate viral entry.

Classical swine fever virus (CSFV) is the causative agent of classical swine fever. Its envelope comprises glycoproteins E(rns), E1, and E2. In this study, we showed that the unmodified CSFV glycoproteins could incorporate into the HIV core to generate an infectious CSFV pseudotyped virus. The infection was specific to several porcine cell lines, and could be neutralized by anti-E2 monoclonal antibodies (mAbs) completely and by anti-E(rns) mAbs partially, indicating that this pseudotyped virus can mimic the early infection steps of parental CSFV. To investigate the specific role of each envelope protein involved in viral entry, a series of pseudotyped viruses were generated bearing CSFV glycoproteins in various combinations. It was found that specific infectivity was also achieved with non-E(rns) pseudotyped virus carrying E1 and E2 glycoproteins. This indicated that E1 and E2 are sufficient to mediate CSFV entry, and E(rns) is not indispensable in this process.