Using the modified CRISPR-Cas9 gene editing system and a therapeutic strategy known as long-acting slowly effective releasing antiviral therapy (LASER ART), a team of researchers has eliminated replication competent HIV-1 DNA from the genomes of live mice. Published in the journal Nature Communications the study marks a critical step towards the development of a possible cure for human HIV infection.
"Our study shows that treatment to suppress HIV replication and gene editing when given sequentially can remove HIV from cells and organs of infected animals," said Professor Kamel Khalili of Lewis Katz School of Medicine at Temple University. .
Current HIV treatment focuses on the use of antiretroviral therapy (ART), which suppresses HIV replication, but does not eliminate the virus from the body.
Therefore, the therapy is not a cure for HIV and it requires lifelong use. If it is stopped, HIV retrieves, renews replication and promotes the development of AIDS.
HIV rebound is directly related to the ability of the virus to integrate its DNA sequence into the immune system's genomes, where it is in sleep and outside antiretroviral drugs.
In previous work, Professor Khalili and colleagues used CRISPR-Cas9 to develop a new gene editing and gene therapy delivery system to remove HIV DNA from genomes harboring the virus. In rats and mice, it was found that the gene editing system called AAV9-CRISPR-Cas9 could effectively exclude large fragments of HIV DNA from infected cells, significantly affecting viral gene expression. Like ART, gene editing cannot completely eliminate HIV alone.
For the new study, the researchers combined their gene editing system with the LASER ART therapy, which targets viral shrines and maintains HIV replication at low levels for longer periods, reducing the frequency of ART administration.
The long-term drugs were made possible by pharmacological changes in the chemical structure of the antiretroviral drug. The modified drug was packaged in nanocrystals which are readily distributed to tissues where HIV is likely to lie dormant. Then, the nanocrystals stored in cells for weeks release the drug release slowly.
"We wanted to see if LASER ART could suppress HIV replication long enough for CRISPR-Cas9 to completely remove cells from viral DNA," says Professor Khalili.
To test their idea, Professor Khalili and co-authors used mice designed to produce human T cells susceptible to HIV infection, allowing long-term viral infection and ART-induced latency.
Once infection was established, mice were treated with LASER ART and subsequently with CRISPR-Cas9.
At the end of the treatment period, mice were examined for viral load. Analyzes revealed complete elimination of HIV DNA in about one-third of HIV-infected mice.
"The great message about this work is that it takes both CRISPR-Cas9 and virus suppression through a method such as LASER ART, administered together, to induce a cure for HIV infection," says Professor Khalili. Now you have a clear idea of moving on to trials in non-human primates and possibly clinical trials in humans throughout the year.
Prasanta K. Dash et al. ] 2019. Sequential LASER ART and CRISPR Treatments Eliminate HIV-1 in a subset of infected humanized mice Nature Communications 10, article number: 2753; doi: 10,1038 / s41467-019-10366-y