Hematopoietic Precursor Cells Isolated From Patients on Long-term Suppressive HIV Therapy Did Not Contain HIV-1 DNA

Background. We address the key emerging question of whether Lin−/CD34+ hematopoietic precursor cells (HPCs) represent an important latent reservoir of human immunodeficiency virus type 1 (HIV-1) during long-term suppressive therapy. Methods. To estimate the frequency of HIV-1 infection in bone marrow, we sorted Lin−/CD34+ HPCs and 3 other cell types (Lin−/CD34−, Lin−/CD4+, and Lin+/CD4+) from 8 patients who had undetectable viral loads for 3–12 years. Using a single-proviral sequencing method, we extracted, amplified, and sequenced multiple single HIV-1 DNA molecules from these cells and memory CD4+ T cells from contemporaneous peripheral blood samples. Results. We analyzed 100 000–870 000 bone marrow Lin−/CD34+ HPCs from the 8 patients and found no HIV-1 DNA. We did isolate HIV-1 DNA from their bone marrow Lin+/CD4+ cells that was genetically similar to HIV-1 DNA from lymphoid cells located in the peripheral blood, indicating an exchange of infected cells between these compartments. Conclusions. The absence of infected HPCs provides strong evidence that the HIV-1 infection frequency of Lin−/CD34+ HPCs from bone marrow, if it occurred, was <.003 % (highest upper 95 % confidence interval) in all 8 patients. These results strongly suggest that Lin−/CD34+ HPCs in bone marrow are not a source of persisten