ERVW-1 and influenza: Chimeric virus-like particles (VLPs), such as those based on hepatitis E (Jariyapong et al., 2013), Norwalk virus (Ball et al., 1998), HIV env (Takamura et al., 2004) and influenza (Serradell et al., 2019), have demonstrated protease resistance and strong immune responses after oral administration in animal models.