Monocytes harbour replication-competent, non-latent HIV-1 in patients on highly active antiretroviral therapy

Objective: To determine whether HIV-1 can be recovered from blood monocytes as well as resting, memory CD4 T lymphocytes of patients on highly active antiretroviral therapy (HAART) with undetectable plasma viraemia and whethe r infection is active or latent. Design: Five patients with plasma HIV-1-RNA levels of less than 500 copies/ ml for at least 3 months and less than 50 copies/ml at the time of sampling were initially selected, followed by an additional five patients with vira l loads of less;than 50 copies/ml for 3 months or more. Methods: Monocytes were isolated from blood by plastic adherence, then furt her purified by a second adherence step or CD3 depletion before co-culture with CD8-depleted donor peripheral blood mononuclear cells. Virus isolates were examined for mutations conferring resistance to reverse transcriptase or protease inhibitors and for genotype. The highly purified monocytes were also analysed for the presence of proviral and unintegrated viral DNA and multiply spliced (MS) viral mRNA by polymerase chain reaction. Results: Virus was recovered from monocytes of five patients. Sequencing of the recovered viruses did not reveal multiple drug resistance, and was con sistent with a non-syncytium-inducing/CCR5 phenotype. Proviral DNA was dete ctable in monocytes from all subjects, and unintegrated HIV-1 DNA and MS RN A was found in four out of five populations examined. Conclusion: Recovery of replication-competent virus from some HAART patient s indicates that monocytes can also harbour HIV-1. Detection of circular, v iral DNA and spliced RNA, albeit at very low levels, in these cells suggest s that their infection is recent and transcriptionally active rather than l atent. (C) 2001 Lippincott Williams & Wilkins.