(V.A. Belyi, A J. Levine, A. Skalka. 2010. Sequences from Ancestral Single-Stranded DNA Viruses in Vertebrate Genomes: the Parvoviridae and Circoviridae Are More than 40 to 50 Million Years Old. Journal of Virology; 84.23: 12458-12462.)
Cellular Protein Hobbles HIV-1
A cellular protein called BST-2 had already been known to interfere with the spread of human immunodeficiency virus type 1 (HIV-1), by inhibiting the release of its progeny particles from infected cells. Now a team from McGill University, Montreal, shows that in addition, each progeny virion's ability to cause infection is severely impaired.
"BST-2 may exert a more potent inhibition effect on HIV-1 transmission than previously thought," says coauthor Chen Liang. The research is published in the December Journal of Virology.
BST-2 appears to attenuate infectivity of progeny particles by interfering with their maturation. Normally, during synthesis of new virus particles, a protein called PR55Gag is cleaved into three major structural proteins of HIV. "This cleavage process transforms HIV-1 from an immature and non-infectious virion into a mature and infectious virion," says Chen. The protease inhibitors, drugs given to AIDS patients to contain the disease, block this step. Similarly, BST-2 seems to interfere with this step, because in the study, its presence was associated with accumulation of uncleaved Gag precursor and intermediate products. The mechanism of that interference has yet to be elucidated.
BST-2 (bone marrow stromal cell antigen-2), also known as tetherin, is a cellular protein which has been shown to rest
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American Society for Microbiology