Download View/Open

Virus Research
Volume 150, Issues 1–2,
June 2010, Pages 153–157
In vitro assembly of the feline immunodeficiency virus
Gag polyprotein

José L. Affranchino, ,

Silvia A. González
Abstract
The retroviral Gag protein is the only viral product that is necessary for the assembly of virions in
mammalian cells. We have established an in vitro assembly system to study the assembly properties of
purified feline immunodeficiency virus (FIV) Gag protein expressed in bacteria. Under fully defined
conditions, the FIV Gag protein assembles into spherical particles of 33 nm in diameter which are
morphologically similar to authentic immature particles, albeit smaller than virions. The in vitro assembly of
FIV Gag into particles was found to be resistant to the addition of Triton X-100 and required the presence
of RNA. Notably, we found that an amino acid substitution in the nucleocapsid domain of Gag that impairs
RNA binding and blocks virion production in vivo, also abrogates Gag assembly in vitro. The development
of an in vitro assembly system for FIV Gag protein will facilitate the study of the mechanisms by which this
protein assembles into immature particles.
Keywords

Feline immunodeficiency virus;

Gag polyprotein;

In vitro assembly;

Lentiviruses
Corresponding author. Tel.: +54 11 4511 4701; fax: +54 11 4963 9278.
Copyright © 2010 Elsevier B.V. All rights reserved.