Background
Plasma viral loads (VL) in persons with HIV (PWH) taking antiretroviral therapy are generally below the limit of quantification. However, commercial PCR tests differentiate between unquantifiable low, but detectable VL (<40 c/ml, residual viremia, RV) and Target Not Detected (TND). Whether RV drives or is driven by systemic immune activation remains debated. Large studies are lacking, and results are conflicting. In two cohorts of PWH, we examined associations between RV, systemic immunologic effects, and reservoir composition and size.
Methods
The 2000HIV study (NCT03994835), enrolling 1895 virally suppressed PWH in the Netherlands, divided into a discovery and validation cohort, was used to compare participants with RV and TND. We performed extensive immunophenotyping of circulating immune cells, measured cytokine production after ex-vivo stimulation in PBMCs and plasma proteome using Olink Explore panel (~3000 proteins). Differential expression analysis between RV and TND was performed, followed by gene set enrichment analysis (GSEA) using Hallmark library on proteins expressed in the same direction in both cohorts. Additionally proviral Cell Associated-HIV-DNA (CA-DNA) in circulating CD4 T cells were analyzed, along with intactness ratio using the Rainbow assay.
Results
The discovery cohort included 474 PWH with RV and 1002 with TND, the validation cohort had 136 with RV and 190 with TND. No significant differences in immune cell populations, their activation markers and cytokine production capacity were found between RV and TND. There were no significant differentially expressed proteins, but GSEA identified 16 enriched pathways (Figure 1). PLHIV with RV had significantly higher total CA-DNA copies per 106 CD4-T cells in both the discovery (median [IQR]: RV 875 [387-1600] vs. TND 481 [191-1047], p<0.00) and validation cohort (RV 873 [331-1908] vs. TND 442 [200-1092], p<0.00). While the intactness ratio was similar, both intact and defective copies were higher in RV.
Conclusions
RV is associated with higher total viral reservoir size, without differences in intactness ratio. Remarkably in this large study in PWH no sings of systemic inflammation or immune activation were found in RV. GSEA reveals upregulation of epithelial mesenchymal transition, that links with impaired mucosal barrier function and human papillomavirus malignancies, suggeting RV could potentially play a role in these conditions, warranting further investigation into its clinical significance and therapeutic options
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