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

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 persistent