Scientists have eliminated HIV in mice for the first time. Is a cure for humans coming?

A Journal of People report

Scientists have successfully eliminated HIV from the DNA of infected mice for the first time, bringing them one-step closer to curing the virus in humans. A research report says this advancement of science.

The research report – “Sequential LASER ART and CRISPR Treatments Eliminate HIV-1 in a Subset of Infected Humanized Mice” – has been published in Nature Communications (volume 10, Article number: 2753 (2019)) on July 2, 2019.

Scientists from Temple University and the University of Nebraska Medical Center were able to eliminate the virus using a combination of gene-editing technology and a slow-release antiviral drug, according to the research report.

The report by Prasanta K. Dash, Rafal Kaminski, Ramona Bella, Hang Su, Saumi Mathews, Taha M. Ahooyi, Chen Chen, Pietro Mancuso, Rahsan Sariyer, Pasquale Ferrante, Martina Donadoni, Jake A. Robinson, Brady Sillman, Zhiyi Lin, James R. Hilaire, Mary Banoub, Monalisha Elango, Nagsen Gautam, R. Lee Mosley, Larisa Y. Poluektova, JoEllyn McMillan, Aditya N. Bade, Santhi Gorantla, Ilker K. Sariyer, Tricia H. Burdo, Won-Bin Young, Shohreh Amini, Jennifer Gordon, Jeffrey M. Jacobson, Benson Edagwa, Kamel Khalili & Howard E. Gendelman said in its introduction:

“According to UNAIDS, it is estimated that more than 36.7 million people worldwide are infected with the human immunodeficiency virus type one (HIV-1) and >5000 individuals worldwide are newly infected each day.”

It said:

“In the clinic, antiretroviral therapy (ART) restricts viral infection by stalling various steps of the viral life cycle. However, ART fails to eliminate integrated copies of HIV-1 proviral DNA from the host genome. As such, virus persists in a latent state within infectious reservoirs; and ART cessation readily leads to viral reactivation and disease progression to acquired immunodeficiency syndrome (AIDS). Thus, a major issue for any HIV-1 curative strategy is the means to eliminate either integrated proviral DNA or the cells that harbor virus without collateral cytotoxic reactions.”

The “Introduction” of the report also said:

“However, elimination of HIV-1 infection in its infected human host is documented only in two individuals. There are several reasons why success has not yet been realized. This includes inadequate therapeutic access to viral reservoirs, rapid spread of infection by continuous sources of virus and susceptible cells and a failure to eliminate residual latent integrated proviral DNA. All single or combination therapeutic approaches preclude HIV-1 cure as viral rebound universally follows ART cessation. Yet, another obstacle towards elimination of infection is that viral latency is established after infection onset and precedes peak viremia.”

It said:

“This underscores that early intervention with potent antiretroviral medicines may help to further reduce the size of the reservoir and ultimately facilitate viral elimination. Therefore, multimodal robust pharmaceutic strategies are needed for complete elimination of HIV-1 if no viral resurgence after cessation of ART is to be achieved. To address this need and design a suitable therapeutic strategy, our laboratories produce highly hydrophobic lipophilic viral reservoir penetrating antiretroviral prodrugs coined as long-acting slow-effective release ART (LASER ART). LASER ART properties are defined by slow drug dissolution, enhanced lipophilicity, improved bioavailability and limited off-target toxicities, which directly affect the frequency of ART administration from daily to weeks. These reduce disease co-morbidity in small animals and maintains effective antiretroviral drug concentrations in blood and tissue viral reservoirs from days to weeks. Macrophages enable uptake of significant amounts of intracellular antiretroviral drug crystals and tightly control ongoing viral replication by the cells’ slow drug release and transfer to adjacent CD4 + T cells during cell-to-cell contact or through direct drug uptake. However, LASER ART alone cannot rid the infected host of latent HIV-1 no matter how successful the drugs may prove to be at restricting viral infection. Thus, in parallel, we develop CRISPR-Cas9 based gene editing technology using AAV9 delivery that specifically and efficiently excises fragments of integrated HIV-1 proviral DNA from the host genome.”

It added:

“We realize that CRISPR-Cas9-based technologies could be most effective in the setting of maximal viral restriction and substantive reductions in the absolute proviral DNA load. Thus, the two approaches are combined to examine whether LASER ART and CRISPR-Cas9 treatments could provide combinatorial benefit for viral elimination. Here we demonstrate elimination of replication competent HIV-1 in an experimental model of human infectious disease. Viral clearance is achieved from HIV-1 infected spleen and lymphoid tissues as well as a broad range of solid organs from documented prior infected humanized mice treated with LASER ART and AAV9-CRISPR-Cas9. This is confirmed in those mice using ultrasensitive HIV-1 nucleic acid detection methods by the absence of post-treatment viral rebound; and by the inability to transfer virus from those infected and dual-treated mice to replicate uninfected untreated mice. We conclude that viral elimination by a combination of LASER ART and gene editing strategy is possible.”

“The possibility exists that HIV can be cured,” said Howard Gendelman, chairman of UNMC’s pharmacology and experimental neuroscience department and study author. “It’s going to take a little bit of time but to have the proof of concept gets us all excited.”

If a patient stops taking the drugs, HIV is able to rebound because the virus is able to “integrate its DNA sequence into the genomes of cells of the immune system, where it lies dormant and beyond the reach of antiretroviral drugs,” according to a press release.

Researchers used a new form of ART called LASER ART on 23 “humanized mice,” animals genetically modified to bear similarities to the human immune response. They were able to control the release and metabolism of the drug, which allowed it to suppress virus replication for longer period of time.

The team then excised the remaining integrated HIV genome using a gene-editing tool called CRISPR-Cas9, which allows scientists to operate on DNA to add or disable certain genes.

“That’s why we believe this technology is working because the LASER ART is reducing the virus significantly and then the CRISPR comes in and it’s able to be more effective,” Gendelman said. “They work at different stages, but put together they’re kind of buddies.”

Gendelman emphasized that the process “only is successful if we get rid of every virus in the body.” The treatment worked on 9 of the 23 mice involved.

“We had to be highly efficient and getting a third of these animals cured is amazing considering what we were up against.”

Gendelman said its unclear how long it will take before clinical trials can begin noting that more research needs to be done into the potential of toxicity of gene modifying therapy and how to scale up the dose for humans.

“We’re working on this day and night and we hope it’ll be sooner than later, but we have some obstacles to overcome,” he said. “There’s a tremendous amount of effort to move this technology forward.”

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