Human TRIM5α Expression Levels and Reduced Susceptibility to HIV-1 Infection

Background. Human TRIM5 alpha (TRIM5 alpha hu), a member of the tripartite motif protein family, displays some anti-human immunodeficiency virus type 1 (HIV-1) activity in vitro, although it is substantially less potent than its rhesus monkey counterpart (TRIM5 alpha rh). The effects of levels of TRIM5 alpha hu on prevention or control of HIV-1 infection in vivo are unknown. Methods. We used a quantitative real-time polymerase chain reaction (PCR) assay to measure levels of TRIM5 alpha hu expression in peripheral blood mononuclear cells (PBMCs) obtained from a cohort of individuals at high risk for HIV-1 infection in Durban, South Africa. Samples were available from 38 infected subjects (with all these samples obtained within 1 year of infection) and from 57 uninfected persons. Matched preinfection and postinfection samples were available from 13 individuals. Results. TRIM5 alpha hu messenger RNA levels were lower in the PBMCs of HIV-1-infected subjects than in those of uninfected subjects (P < .001). Seroconverters had lower preinfection levels of TRIM5 alpha hu than did nonseroconverters (P < .001). TRIM5 alpha hu levels did not change significantly after infection. There was no correlation between TRIM5 alpha hu levels and viral loads or CD4(+) T cell counts. Conclusions. High expression of TRIM5 alpha hu is associated with reduced susceptibility to HIV-1 infection. Furthermore, infection is not associated with disregulation of TRIM5 alpha hu. TRIM5 alpha hu expression levels do not contribute to the control of primary HIV-1 viremia.