Innate intracellular resistance to HIV-1

drj writes "Human immunodeficiency virus type 1 (HIV-1), the cause of acquired immunodeficiency syndrome (AIDS) in humans, efficiently enters Old World monkey cells but it is not reverse transcribed. This block probably protects monkeys from productive HIV-1 infection and AIDS. Stremlau and colleagues searched for an Old World monkey (rhesus) gene blocking HIV-1 infection by transferring an expression library into a susceptible human cell line (HeLa) and testing for HIV-1 resistance. They found TRIM5a, a 497 amino acid protein located in cytoplasmic bodies and named only for its structural "tripartite motif". Inhibition might result from the ubiquitin ligase activities of TRIM5a, which marks a protein for degradation but here might simply interfere with capsid disassembly. Notably, the rhesus TRIM5a does not block simian immunodeficiency virus (SIV) infection. Human TRIM5a differs in several key residues that are presumably involved in recognizing HIV-1 capsid.
Stremlau et al. Nature 427:858. February 26, 2004.
'The cytoplasmic body component TRIM5a restricts HIV-1 infection in Old World monkeys' Matthew Stremlau, Christopher M. Owens, Michel J. Perron, Michael Kiessling, Patrick Autissier & Joseph Sodroski"