RSAD2 and viral infectious disease: Viperin expression is increased in response to a number of viral infections and has antiviral actions in vitro, including against human cytomegalovirus (HCMV) [4] chikungunya virus (CHIKV) [5], influenza A virus (IAV) [6], hepatitis C virus (HCV) [7] and several members of the family Flavivirus, such as West Nile virus (WNV) [8, 9], tick-borne encephalitis virus (TBEV) [9], dengue virus (DENV) [10] and zika virus (ZIKV) [8].