Covalent bonded Gag multimers in human immunodeficiency virus type-1 particles


Hidehiro Takahashi, Department of Pathology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan. Tel: +81 3 5285 1111; fax: +81 3 5285 1189; email:


The oligomerization of HIV-1 Gag and Gag-Pol proteins, which are assembled at the plasma membrane, leads to viral budding. The budding generally places the viral components under non-reducing conditions. Here the effects of non-reducing conditions on Gag structures and viral RNA protection were examined. Using different reducing conditions and SDS-PAGE, it was shown that oligomerized Gag possesses intermolecular covalent bonds under non-reducing conditions. In addition, it was demonstrated that the mature viral core contains a large amount of covalent bonded Gag multimers, as does the immature core. Viral genomic RNA becomes sensitive to ribonuclease in reducing conditions. These results suggest that, under non-reducing conditions, covalent bonded Gag multimers are formed within the viral particles and play a role in protection of the viral genome.