Seminal Reservoirs during an HIV-1 Eradication Trial

G Nunnari, J Kulkosky, D Leto, J Sullivan, Y Xu, RJ Pomerantz. Center for Human Virology, Division of Infectious Diseases, Department of Medicine, Thomas Jefferson University, 1020 Locust street #329, Philadelphia, PA 19107 (USA).

Background: Despite of the drastic reduction of the levels of HIV-1 virions in blood and seminal plasma of HIV-1-infected patients, HAART does not eradicate HIV-1 disease. Low-levels of viral replication can be demonstrated in patients with undetectable plasma HIV-1 RNA load, and viral rebound occurs after interruption of therapy. Residual HIV-1 disease was approached in vivo with a rationally designed combination therapeutic eradication protocol, and the role of the seminal compartment in the phenomenon of viral rebound was investigated. Material and Methods: 3 HIV-1 infected patients, with < 50 copies/ml of plasma viral RNA for > 1 year, were enrolled in this trial. DDI and hydroxyurea (HU) were added to their baseline HAART to attack cryptic viral replication. After a month of therapy, low dose OKT3, followed by a 2-week course of IL-2 were administrated to stimulate latent provirus. Plasma viral RNA and 2-LTR DNA circles were analyzed. CD8-depleted PBMCs and semen cells were studied in co-culture to detect replication-competent virus. The sequences of the V3 loop of the gp120 region were aligned for cell-free RNA and proviral DNA in blood and seminal compartments at different time-points. Results: AHU and DDI were continued with HAART after OKT3 and IL-2 stimulation. Replication-competent virus was undetectable after treatment and plasma viral RNA was either undetectable or very low in each of the patients. When the three patients were given trials off all antiretroviral therapy, they developed blood, but not seminal, viral rebound. Based on viral sequences and tropism, we found that the two major viral isolates, in semen cells, were macrophage-tropic (CCR5) and dual-tropic (CXCR4 and CCR5), and these were also present in PBMCs. Six months after the viral rebound, we demonstrated a shift toward dual tropism in semen cell-associated HIV-1 proviral DNA, with the first appearance of a T-lymphotropic (CXCR4) virus solely in this compartment. The virus responsible for the blood plasma viral rebound was not found in the semen microenvironment, neither before nor at completion of the protocol. Conclusion: This study suggests viral compartmentalization of the semen microenvironment after an intensification and stimulatory protocol, with evidence of viral evolution. Whether the latter will play an active role, as a viral reservoir, along the course of HIV-1 disease is being analyzed in on-going studies.