A novel fusion gene, TRIMS-Cyclophilin A in the pig-tailed macaque determines its susceptibility to HIV-1 infection

Objective: In Old World monkeys, the tripartite motif Sec (TRIM5 alpha) protein confers resistance to HIV-1 infection following virus entry into host cells. However, the pig-tailed macaque (Macaca nemestrina) is an exception and is susceptible to HIV-1 infection. This study dissects the molecular mechanism of the pig-tailed macaque's susceptibility to HIV-1 infection. Methods: Genomic sequencing and expression analysis of the TRIM5a gene was conducted in the pig-tailed macaque. A novel TRIMS-Cyclophilin A fusion gene isoform was identified and subsequently cloned into the pcDNA3.1(+) expression vector. This construct was transfected into HeLa-T4 or HeLa cells which were then infected with the HIV-1(IIIB) or HIV-GFP-VSVG pseudotyped virus, to examine the effects of the TRIMS-Cyclophilin A fusion protein on HIV-1 infection. Results: A novel TRIMS-Cyclophilin A fusion gene (rnnTRIMCyp) in the pig-tailed macaque was found and its fusion pattern is different from the known fusion gene in the owl monkey (owITRIMCyp). TRIMCyp protein expression in transfected cells was confirmed by western blotting. The tests using HIV-1(IIIB) and HIV-GFP-VSVG pseudotyped virus indicated that mnTRIMCyp did not inhibit HIV-1 replication at various multiplicities of infection. Conclusions: The mnTRIMCyp fusion protein does not restrict replication of HIV-1, which provides a potential molecular mechanism that might explain why the pig-tailed macaque is prone to HIV-1 infection, the only known exception in Old World monkeys. (c) 2007 Wolters Kluwer Health-Lippincott Williams & Wilkins.