Reduction of N-tropic mutant porcine endogenous retrovirus infectivity by human tripartite motif-containing 5-isoform alpha.

In cases of retroviral infection, the host cell deploys antiviral proteins as a type of innate immunity. Tripartite motif-containing 5-isoform alpha (TRIM5α) is a potent antiviral protein. TRIM5α has been reported to restrict human immunodeficiency virus (HIV) 1 infection in rhesus monkey cells by targeting the incoming viral capsid at the postentry or preintegration stage of the viral life cycle. As a consequence, virus replication and reverse transcription are interrupted. TRIM5α of human origin has also been shown to inhibit N-tropic murine leukemia virus infection. To investigate the inhibitory effect of TRIM5α on porcine endogenous retrovirus (PERV) infection in humans, we constructed a 293T cell line stably expressing human TRIM5α (293T-huTRIM5α) and tested the infectivity of vesicular stomatitis virus glycoprotein envelope pseudotyped viruses (wild-type PERV [wt-PERV], N-tropic mutant PERV, N-tropic murine leukemia virus, and MoMLV). Infectivity of N-tropic mutant PERV was reduced by 43.3% in 293T-huTRIM5α cells, a decrease in efficiency that was more than 3-fold greater than that of wt-PERV in 293T-huTRIM5α cells. Human TRIM5α exhibited inhibitory activity against N-tropic MLV and N-tropic mutant PERV, but showed no antiviral activity against Moloney murine leukemia virus or wt-PERV.