CD209 and severe acute respiratory syndrome: Han et al. conducted experiments using HeLa cells that were not infected with SARS-CoV and found that SARS-CoV pseudovirus could infect cells transfected with ACE2, DC-SIGN, or L-SIGN plasmids but not control cells that had been transfected with empty vectors, suggesting that DC-SIGN/L-SIGN can mediate SARS-CoV infection independently of ACE2.