HIV-like virus edited out of primate genome
Coming closer to a cure for human HIV infection

Date:
November 30, 2020
Source:
Temple University Health System
Summary:
Taking a major step forward in HIV research, scientists have
successfully edited SIV - a virus closely related to HIV, the
cause of AIDS - from the genomes of non-human primates.



FULL STORY ========================================================================== Taking a major step forward in HIV research, scientists at the Lewis Katz School of Medicine at Temple University have successfully edited SIV --
a virus closely related to HIV, the cause of AIDS -- from the genomes
of non-human primates. The breakthrough brings Temple researchers and
their collaborators closer than ever to developing a cure for human
HIV infection.


==========================================================================
"We show for the first time that a single inoculation of our CRISPR
gene- editing construct, carried by an adeno-associated virus, can edit
out the SIV genome from infected cells in rhesus macaque monkeys,"
said 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 the Lewis Katz
School of Medicine at Temple University (LKSOM).

Dr. Khalili was a senior co-investigator on the new study, with Tricia H.

Burdo, PhD, Associate Professor and Associate Chair of Education in the Department of Neuroscience at LKSOM, who is an expert on the utilization
of the SIV (simian immunodeficiency virus)-infected antiretroviral therapy (ART)- treated rhesus macaque model for HIV pathogenesis and cure studies;
and with Andrew G. MacLean, PhD, Associate Professor at the Tulane
National Primate Research Center and the Department of Microbiology and Immunology at Tulane University School of Medicine, and Binhua Ling,
PhD, Associate Professor at the Southwest National Primate Research
Center, Texas Biomedical Research Institute. Dr. Ling was previously
Associate Professor at the Tulane National Primate Research Center and
the Department of Microbiology and Immunology at Tulane University
School of Medicine. Pietro Mancuso, PhD, an Assistant Scientist in
Dr. Khalili's laboratory in the Department of Neuroscience at LKSOM,
was first author on the report, which was published online November 27
in the journal Nature Communications.

Of particular significance, the new work shows that the gene-editing
construct developed by Dr. Khalili's team can reach infected cells and
tissues known to be viral reservoirs for SIV and HIV. These reservoirs,
which are cells and tissues where the viruses integrate into host DNA
and hide away for years, are a major barrier to curing infection. SIV or
HIV in these reservoirs lies beyond the reach of ART, which suppresses
viral replication and clears the virus from the blood. As soon as ART is stopped, the viruses emerge from their reservoirs and renew replication.

In non-human primates, SIV behaves very much like HIV. "The SIV-infected
rhesus macaque model studied in Dr. Burdo's lab is an ideal large animal
model for recapitulating HIV infection in humans," explained Dr. Khalili.

For the new study, the researchers began by designing an SIV-specific
CRISPR- Cas9 gene-editing construct. Experiments in cell culture confirmed
that the editing tool cleaved integrated SIV DNA at the correct location
from host cell DNA, with limited risk of potentially harmful gene editing
at off-target sites.

The research team then packaged the construct into an adeno-associated
virus 9 (AAV9) carrier, which could be injected intravenously into
SIV-infected animals.

Dr. Burdo, in collaboration with colleagues at Tulane National Primate
Research Center, randomly selected three SIV-infected macaques to each
receive a single infusion of AAV9-CRISPR-Cas9, with another animal
serving as a control. After three weeks, the researchers harvested blood
and tissues from the animals.

Analyses showed that in AAV9-CRISPR-Cas9-treated macaques, the
gene-editing construct had been distributed to a broad range of tissues, including the bone marrow, lymph nodes, and spleen, and had reached CD4+
T cells, which are a significant viral reservoir.

Moreover, the Temple researchers demonstrated that the SIV genome was effectively cleaved from infected cells, based on genetic analyses of
tissues from treated animals. "The step-by-step excision of SIV DNA
occurred with high efficiency from tissues and blood cells," Dr. Mancuso explained. Excision efficiency varied by tissue but reached notably high
levels in the lymph nodes.

The new study is a continuation of efforts by Dr. Khalili and colleagues
to develop a novel gene-editing system using CRISPR-Cas9 technology --
the subject of the 2020 Nobel Prize in Chemistry -- to specifically
remove HIV DNA from genomes harboring the virus. The researchers have
shown previously that their system can effectively eliminate HIV DNA
from cells and tissues in HIV-infected small animal models, including
HIV-1 humanized mice.

Co-corresponding author Dr. MacLean is encouraged by the findings. "This
is an important development in what we hope will be an end to HIV/AIDS,"
says MacLean. "The next step is to evaluate this treatment over a longer
period of time to determine if we can achieve complete elimination of the virus, possibly even taking subjects off of ART." Dr. MacLean is hopeful
that this treatment strategy will translate to the human population. The biotech company Excision BioTherapeutics, of which Dr. Khalili is
a scientific founder and where Dr. Burdo contributes to preclinical
research and development and serves on the Scientific Advisory Board,
will assist with funding and infrastructure for larger scale studies and
future clinical trials after approval by the Food and Drug Administration.

"We hope to soon move our work into clinical studies in humans as
well," Dr.

Khalili added. "People worldwide have been suffering with HIV for 40
years, and we are now very near to clinical research that could lead to
a cure for HIV infection."

========================================================================== Story Source: Materials provided by Temple_University_Health_System. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Pietro Mancuso, Chen Chen, Rafal Kaminski, Jennifer Gordon,
Shuren Liao,
Jake A. Robinson, Mandy D. Smith, Hong Liu, Ilker K. Sariyer, Rahsan
Sariyer, Tiffany A. Peterson, Martina Donadoni, Jaclyn B. Williams,
Summer Siddiqui, Bruce A. Bunnell, Binhua Ling, Andrew G. MacLean,
Tricia H. Burdo, Kamel Khalili. CRISPR based editing of SIV proviral
DNA in ART treated non-human primates. Nature Communications,
2020; 11 (1) DOI: 10.1038/s41467-020-19821-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/11/201130131402.htm

--- up 14 weeks, 7 hours, 51 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)