Cholesterol dependence of HTLV-I infection

Cholesterol- rich plasma membrane microdomains are important for entry of many viruses, including retroviruses. Depletion of cholesterol with 2- hydroxypropyl- beta- cyclodextrin inhibits entry of human T cell leukemia virus type I ( HTLV- 1) and HTLV- I envelope pseudotyped lentivirus particles. Using a soluble fusion protein of the HTLV- I surface envelope protein with the immunoglobulin Fc domain, the HTLV- I receptor was found to colocalize with a raft- associated marker and to cluster in specific plasma membrane microdomains. Depletion of cholesterol did not alter receptor binding activity, suggesting a requirement for cholesterol in a postbinding virus entry step.