Quoting myself: >there's no reason to suspect that a mutation in CCR5< Should have said "mutation to CXCR4 tropism." Here's a reference. <A HREF="http://gateway.nlm.nih.gov/MeetingAbstracts/102249495.html" target="_blank">http://gateway.nlm.nih.gov/MeetingAbstracts/102249495.html</A>