TRIM5α restriction affects clinical outcome and disease progression in simian immunodeficiency virus-infected rhesus macaques

Tripartite motif-containing protein 5α (TRIM5α) is considered to be a potential target for cell-based gene modification therapy against human immunodeficiency virus type 1 (HIV-1) infection. In the present study, we used a relevant rhesus macaque model of infection with simian immunodeficiency virus from sooty mangabey (SIVsm) to evaluate the effect of TRIM5α restriction on clinical outcome. For macaques expressing a restrictive TRIM5 genotype, the disease outcomes of those infected with the wild-type TRIM-sensitive SIVsm strain and those infected with a virus with escape mutations in the capsid were compared. We found that TRIM5α restriction significantly delayed disease progression and improved the survival rate of SIV-infected macaques, supporting the feasibility of exploiting TRIM5α as a target for gene therapy against HIV-1. Furthermore, we also found that preservation of memory CD4 T cells was associated with protection by TRIM5α restriction, suggesting memory CD4 T cells or their progenitor cells as an ideal target for gene modification. Despite the significant effect of TRIM5α restriction on survival, SIV escape from TRIM5α restriction was also observed; therefore, this may not be an effective stand-alone strategy and may require combination with other targets.

Importance: Recent studies suggest that it may be feasible not only to suppress viral replication with antiviral drugs but also potentially to eliminate or "cure" human immunodeficiency virus (HIV) infection. One approach being explored is the use of gene therapy to introduce genes that can restrict HIV replication, including a restrictive version of the host factor TRIM5α. TRIM5 was identified as a factor that restricts HIV replication in macaque cells. The rhesus gene is polymorphic, and some alleles are restrictive for primary SIVsm isolates, although escape mutations arise late in infection. Introduction of these escape mutations into the parental virus conferred resistance to TRIM5 on macaques. The present study evaluated these animals for long-term outcomes and found that TRIM5α restriction significantly delayed disease progression and improved the survival rate of SIV-infected macaques, suggesting that this could be a valid gene therapy approach that could be adapted for HIV.