HTLV-1 structural proteins.

HTLV-1 structural proteins do not appear to ensure virus transmission as efficiently as most other retrovirus structural proteins do, whereas all other retroviruses can be transmitted via either free virions or cell-to-cell contacts, infection by HTLV-1 by free virions is very inefficient, and effective infection requires the presence of HTLV-1 infected cells. This characteristic feature of HTLV-1 provides a unique tool which can be used to analyse retrovirus cellular transmission in the absence of simultaneous cell-free infection. Here we summarise what is known about HTLV-1 structural proteins and identify the questions about these proteins which remain to be answered.