Multilineage polyclonal engraftment of Cal-1 gene-modified cells and in vivo selection after SHIV infection in a nonhuman primate model of AIDS

Abstract

We have focused on gene therapy approaches to induce functional cure/remission of HIV-1 infection. Here, we evaluated the safety and efficacy of the clinical grade anti-HIV lentiviral vector, Cal-1, in pigtailed macaques (Macaca nemestrina). Cal-1 animals exhibit robust levels of gene marking in myeloid and lymphoid lineages without measurable adverse events, suggesting that Cal-1 transduction and autologous transplantation of hematopoietic stem cells are safe, and lead to long-term, multilineage engraftment following myeloablative conditioning. Ex vivo, CD4+ cells from transplanted animals undergo positive selection in the presence of simian/human immunodeficiency virus (SHIV). In vivo, Cal-1 gene-marked cells are evident in the peripheral blood and in HIV-relevant tissue sites such as the gastrointestinal tract. Positive selection for gene-marked cells is observed in blood and tissues following SHIV challenge, leading to maintenance of peripheral blood CD4+ T-cell counts in a normal range. Analysis of Cal-1 lentivirus integration sites confirms polyclonal engraftment of gene-marked cells. Following infection, a polyclonal, SHIV-resistant clonal repertoire is established. These findings offer strong preclinical evidence for safety and efficacy of Cal-1, present a new method for tracking protected cells over the course of virus-mediated selective pressure in vivo, and reveal previously unobserved dynamics of virus-dependent T-cell selection.

Loss of immune homeostasis dictates SHIV rebound after stem-cell transplantation

“…Hematopoietic recovery following myeloablative conditioning (1,020 cGy total body irradiation) and transplantation was consistent with previously published results in SHIV-naive animals (Supplemental Figure 1 and ref. 17). Following a total of more than 1 year on cART, all animals were released from cART and necropsied approximately 18 weeks later ( Figure 1A).…”

“…Animals received CD34 + cell doses ranging from 2.08 million to 6.45 million per kilogram body weight. The conditioning regimen for each transplant consisted of a fractionated dose of 1,020 cGy total body irradiation, as previously described (17). Data collection continued through necropsy for each animal, based on our definition of VL rebound in tissues that could not be collected until study endpoint.…”

“…Total body irradiation/myeloablative conditioning results in many changes including lymphocyte depletion and damage to secondary lymphoid tissues such as the gastrointestinal (GI) tract (15)(16)(17). Here we defined the immunological mechanisms at play in SHIV-infected, cART-suppressed macaques following autologous transplantation in our well-established SHIV model.…”

Autologous Stem Cell Transplantation Disrupts Adaptive Immune Responses during Rebound Simian/Human Immunodeficiency Virus Viremia

“…The conditioning regimen for each transplant consisted of a fractionated dose of 1,020 cGy of total body irradiation, as previously described (58). Data collection continued through necropsy for each animal, based on our definition of viral load (VL) rebound in tissues that could not be collected until the study endpoint.…”

Resolving the Sites of HIV Entry: Dynamin Networks Hold the Key

“…In an alternative approach, gene therapy can be used to deliver genes into target cells that can either protect them from new infections, by targeting viral entry [99][100][101] or inducing permanent silencing of the integrated provirus [102,103]. Deleting integrated provirus with gene editing systems such as CRISPR/Cas9 and zinc finger nucleases is also being explored [104][105][106][107][108].…”