Note: this site last updated in 2006
An article from "The Molecules of HIV" (c) Dan Stowell
Actin is a very important protein for practically all cells. Not only is it a fundamental piece of "scaffolding" for structural purposes within the cell, but it's also important for contraction in muscle cells.
A microfilament is a polymer of actin molecules, stacked together to form a tiny rod.
Actin molecules do get incorporated into the newly-budding HIV particle. Is there a good reason for this? Perhaps HIV uses actin for some specific purpose; or perhaps because actin is everywhere in a cell, it gets incorporated by accident (e.g. just because the assembly of new virus needs actin). Watch this space...