Investigators Successfully Eliminate HIV in Mouse Model

For the first time ever, a team of investigators has successfully eliminated replication-competent HIV-1 DNA from the genome of living mice.

The feat was accomplished through a collaborative effort by investigators from the University of Nebraska Medical Center and the Lewis Katz School of Medicine at Temple University. The research was published in an article in Nature Communications.

“What we’ve done is to transform the antiretroviral drugs from a water-soluble, short half-life medicine to a nanocrystal and encased it into a nanoformulation that can be given infrequently and is long-lasting over a period of months up to as long as a year,” Howard Gendelman, MD, Margaret R. Larson Professor of Infectious Diseases and Internal Medicine, chair of the Department of Pharmacology and Experimental Neuroscience and director of the Center for Neurodegenerative Diseases at University of Nebraska Medical Center, explained in an interview with Nebraska’s PBS & NPR Stations. “These nanocrystals can reach lymphoid tissues, like the lymph nodes, the spleen and the gut, as well as the brain, in very high concentrations over long periods of time.

For individuals living with HIV, antiretroviral therapy (ART) can restrict viral infection by stalling various stages of HIV’s viral life cycle. However, because ART does not eliminate integrated copies of the HIV-1 proviral DNA from the host genome, if ART is discontinued viral reactivation can occur and disease progression to AIDS is possible.

Elimination of HIV-1 has only been documented in humans on 2 occasions. The Berlin patient was “cured of HIV” following 2 consecutive hematopoietic stem cell transplants (HSCT) with total body irradiation and the London patient was “functionally cured of HIV” following allogenic HSCT using a homozygous CCR5d32 donor to treat his Hodgkin’s lymphoma.

Despite these 2 cases, the HIV/AIDS clinician community has acknowledged that these cases are rare and not practical solutions for eliminating HIV in the average patient.

According to the investigators on the new study, reasons that elimination of HIV-1 in infected individuals has not been widely realized include inadequate therapeutic access to viral reservoirs, rapid spread of infection by sources of virus and susceptible cells, and a failure to eliminate residual latent integrated proviral DNA.

As such, the laboratories involved in the research designed a “highly hydrophobic lipophilic viral reservoir penetrating antiretroviral prodrugs coined as long-acting slow-effective release ART (LASER ART).” The authors explain that this therapeutic strategy features enhanced lipophilicity, improved bioavailability, and limited off-target toxicities. Due to these properties, the therapy can reduce disease comorbidity in small animals and also maintain effective ART concentrations in blood and tissue viral reservoirs from days to weeks.

However, LASER-ART alone cannot eliminate latent HIV-1 from the host; therefore, the team developed CRISPR-Cas9-based gene editing using AAV₉ delivery that can “excise” fragments of HIV proviral DNA from the host genome.

For the study, the team set out to evaluate if the combination of LASER ART and CRISPR-Cas9 could lead to viral elimination. To assess this, the team used mice engineered to produce human T cells susceptible to HIV infection permitting long-term viral infection and ART-induced latency.

The mice were treated with LASER ART and, subsequently, with CRISPR-Cas9. Analyses of viral gene amplification, flow cytometry, adoptive viral transfers, on target and off target assays, and viral rebound all demonstrate that combination therapies can safely lead to the elimination of HIV-1 infection.

“Results demonstrated that eradication of replication-competent HIV-1 present in infectious cell and tissue sites of infected animals can be achieved,” the authors write. “As such, these proof-of-concept results offer readily defined and realistic pathways toward strategies for HIV-1 elimination.”

In a shared press release, Gendelman and co-senior investigator Kamel Khalili, PhD, Laura H. Carnell Professor and chair of the Department of Neuroscience, director of the Center for Neurovirology, and director of the Comprehensive NeuroAIDS Center at Lewis Katz School of Medicine at Temple University, said: “The big message of this work is that it takes both CRISPR-Cas9 and virus suppression through a method such as LASER ART, administered together, to produce a cure for HIV infection.”

“We now have a clear path to move ahead to trials in non-human primates and possibly clinical trials in human patients within the year,” the senior authors concluded.

Contagion®'s HIV/AIDS Section Editor, Jason Schafer, PharmD, associate professor of pharmacy practice at Thomas Jefferson University, is cautiously optimistic, citing the fact that there is still a long way to go before an HIV cure can be a possibility for humans.

“The results of this study suggest the exciting possibility that HIV can be eliminated from the genome of an infected animal," Schafer said. While this study could represent an important step towards developing a realistic cure for humans, considerable amounts of research are still necessary. I think that many will be following this research closely with cautious optimism.”