Title

Role of transcriptionally-active "defective" HIV-1 proviruses in immunological non-responders: a case-control study

Presenter

Francesca Scrimieri

Authors

F. Scrimieri¹, E. Bastian², M. Smith², C. Rehm², C. Morse³, J. Kuruppu³, M. McLaughlin³, J. Kovacs³, H.C. Lane², H. Imamichi²

Institutions

¹Frederick National Laboratory for Cancer Research, Frederick, United States, ²National Institutes of Health, National Institute of Allergy and Infectious Diseases, Bethesda, United States, ³National Institutes of Health, Critical Care Medicine Department, Bethesda, United States

BACKGROUND: Despite being placed on suppressive antiretroviral therapy (ART), HIV-positive immunological non-responders (INRs) fail to recover their CD4⁺ T-cell count and have increased T-cell activation and inflammation compared to immunological responders (IRs). The involvement of “defective” HIV-1 proviruses in immune activation has recently been suggested. In the present study, we investigated the potential contribution of transcriptionally-competent “defective” HIV-1 proviruses to poor immune recovery observed in INRs.
METHODS: 26 INRs (CD4 <250 cells/µL, pVL<50 for on average 2.7 yrs) and 25 IRs (CD4 =250 cells/µL, pVL<50 for on average 3.9 yrs) on ART were studied. Age, sex, ART regimen and years of ART were matched between the two groups. Activation phenotypes of T-cells were analyzed by 8-color flow cytometry. Levels of HIV-DNA and cell-associated (CA) HIV-RNA were determined by a quantitative PCR/RT-PCR for the Psi-LTR region. Sequences of HIV-DNA (n=677) and CA HIV-RNA (n=209) were assessed by 5’LTR-to-3’LTR single-genome amplification and direct sequencing. Differences in HIV-1 quasispecies profiles of INRs and IRs were assessed by proportion of near full-length intact HIV-1 and number of viral protein-coding regions.
RESULTS: INRs had higher %CD4⁺HLA-DR(+) (23.0 vs. 12.5, p<0.01) and %CD8⁺HLA-DR(+) (41.5 vs. 32.0, p=0.04). Levels of HIV-DNA were similar between INRs and IRs (median 1827 vs. 1575 copies/million CD4⁺, p=0.84). In contrast, levels of CA HIV-RNA were higher in the INR-group (median 1593 vs. 580 copies/million CD4⁺, p=0.03). Proportions of near full-length intact HIV-1 proviruses in INRs and IRs were 5.1% and 5.9%, respectively. No full-length HIV-RNA transcripts were detected in either group, suggesting that ongoing HIV replication is an unlikely explanation for the poor CD4⁺ recovery. All HIV-RNA transcripts were in novel unspliced forms and frequently encoded for Gag and Nef. These transcripts were expressed in similar proportions in INRs and IRs (50% vs. 32% for Gag; 27% vs. 24% for Nef).
CONCLUSIONS: Levels of sub-genomic HIV-RNA transcripts were higher in the INRs than the IRs, suggesting a possible role for biologically-active “defective” proviruses in the INRs. Further work in studying whether or not these levels are correlated with the observed increases in CD4⁺ and CD8⁺ T-cell activation is warranted.

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