PROJECT SUMMARY
HIV persists despite decades of antiretroviral therapy (ART) because of a population of latently infected CD4+ T
cells known as the HIV reservoir. The HIV reservoir is sustained by proliferation of infected CD4+ T cells, which
do not express enough viral protein to be eliminated by HIV-specific immune responses. While proliferation of
cells is a promising target for curing HIV and eliminating the need for lifelong ART, a comprehensive preclinical
structure to develop a lymphocyte anti-proliferation therapeutic strategy does not exist.
The optimal timing of anti-proliferative (AP) therapy is also unknown. Recent evidence suggests that CD4+ T
cell proliferation plays a vital role in generating multiple proliferative clones of latently infected cells extremely
early during untreated HIV infection. We developed a mathematical model which suggests that massive CD4+
T cell proliferation coincident with recovery from CD4+ lymphopenia, occurs during weeks 1-4 of primary HIV
infection and is vital for generating much of the HIV reservoir. We hypothesize that effective AP therapy given
during this critical three-week window will limit the volume and alter the clonal structure of the HIV reservoir.
In Aim 1 of this application, Dr. Adam Spivak will test small molecular agents targeting CD4+ T cell proliferation
given alone and in combination. A comprehensive library of immunomodulatory and chemotherapeutic agents
with high therapeutic potential will be tested for their AP effects ex vivo on uninfected CD4+ T cell cultures, ex
vivo on latently HIV-1 infected cells derived from human donors, and in vivo in uninfected rhesus macaques by
measuring impact on CD4+ T cell turnover using deuterium water labeling. Finally, Dr. Joshua Schiffer will utilize
mathematical models which capture drug pharmacokinetics and pharmacodynamics, as well as the underlying
dynamics of CD4+ T cell subsets within the HIV reservoir, to optimize selection of single drug or combination
anti-proliferative (AP) regimens for dosing of SIV infected animals in Aim 2. Drug regimens will first be ranked
in a tabular form according to predicted potency. The most potent regimen with known safety in humans and
lack of cell toxicity in Dr. Spivak’s ex vivo model will ultimately be selected for Aim 2.
In Aim 2, Dr. Joseph Mudd will evaluate the effects of optimized AP agents on early reservoir formation dynamics
in 24 SIV-infected rhesus macaques: 6 will receive ART alone between weeks 1-37 post infection; 6 will receive
ART alone between weeks 4-40 post infection; 6 will receive ART between weeks 1-37 and optimized AP therapy
between weeks 1-4 post infection; 6 will receive ART between weeks 4-40 and optimized AP therapy between
weeks 1-4 post infection. Optimized AP regimens will be selected based on Dr. Spivak’s experimental data from
Aim 1 coupled with Dr. Schiffer’s mathematical models.
During ART, we will measure the in vivo AP therapeutic effect on 1) SIV reservoir volume with total and intact
SIV DNA, 2) reservoir CD4+ T cell subset composition, 3) in vivo CD4+ T cell turnover with D2O labeling, and 4)
SIV reservoir clonal structure using integration site sequencing, based on frequent longitudinal sampling of blood
and gut tissues. After 36 weeks of ART, we will stop ART and monitor viral rebound for up to 4 months. We
hypothesize that AP therapy between weeks 1 and 4 post infection will reduce total and intact SIV DNA and
decrease reservoir clonality following 6 months of ART and increase time to SIV rebound after ART interruption.
