A Trim5-cyclophilin A fusion protein found in owl monkey kidney cells can restrict HIV-1.

Lv1 restriction of HIV-1 in the cells of Old World monkeys is associated with the expression of the Trim5 gene. Uniquely, in owl monkey kidney cells, HIV-1 restriction is dependent on the ability of incoming viral capsid protein to bind cyclophilin A (CypA). Cloning of the owl monkey Trim5 gene now reveals the presence of an inserted CypA pseudogene within intron 7 of the Trim5 gene. This insertion results in the formation of a chimeric Trim5-CypA transcript. Transfer of a cDNA corresponding to this transcript into human cells confers cyclosporin A-sensitive resistance to HIV-1 infection. The restriction factor appears to be a chimeric protein created by retrotransposon-mediated exon shuffling.