CD44 and infection: West Nile virus (WNV) upregulates cholesterol synthesis to promote its replication; on the contrary, reducing cholesterol production by HMGCR inhibition had an inhibitory effect on WNV replication.8 Hepatitis C virus (HCV) infection leads to the activation of nuclear factor-κB (NF-κB) which can induce the expressions of heparan sulfate proteoglycans (HSPGs) for the upregulations of cholesterol uptake and HCV entry.34 Nevertheless, not all viruses adopts the strategy of increasing cholesterol metabolism.