By
destroying the regulatory genes of the AIDS virus HIV-1 using the
genome editing system CRISPR/Cas9, a Japanese research group has succeeded in
blocking the production of HIV-1 by infected cells.
Human immunodeficiency virus-1 (HIV-1)
infection is a chronic disease affecting more than 35 million people worldwide.
The infection can be controlled by antiretroviral therapy (ART), but
there is still no complete cure. It is hard to eradicate cells latently
infected with HIV-1 in a patient's body because when the virus proliferates,
the viral gene is inserted into the chromosomes in the infected cells.
Genome
editing methods cut specific parts of genes, allowing us to remove or add
sections of the DNA sequence. The recently developed CRISPR/Cas9
system is a promising tool for deactivating the HIV-1 genes that have been
incorporated into the chromosomes of infected individuals.
This
study targeted two genes that regulate the proliferation of HIV-1, known as tat
and rev. Based on genetic information from six major HIV-1 subtypes, the
team designed six types of guide RNA (gRNA) that enable specific genome
editing using the CRISPR/Cas9 system. They created a lentiviral vector that
expresses Cas9 and gRNA. When they introduced this vector to cultured cells
that expressed the regulatory gene products Tat and Rev, they succeeded in
significantly lowering the expression and functions of both Tat and Rev. The
team found no off-target mutations (non-specific genome editing that
unintentionally targets the host cell genes), and the expression of Cas9 and
gRNA did not affect the survival rate of the cultured cells.
By
introducing gRNA and Cas9 to cultured cells with a latent or persistent HIV-1 infection, they were able
to markedly suppress cytokine-dependent HIV-1 reactivation in latently infected
cells and HIV-1 replication from persistently infected cells. Furthermore, by
introducing all six types of gRNA
at the same time, they managed to almost completely block virus production from
the infected cells.
The
research team was led by Associate Professor Masanori Kameoka, Assistant
Professor Tomohiro Kotaki (Kobe University Graduate School of Health Sciences)
and Youdiil Ophinni (Kobe University Graduate School of Medicine). The findings
were published on May 17 in Scientific Reports.
"These
results show that the CRISPR/Cas9
system, by targeting the regulatory genes of HIV-1, tat and rev,
is a promising method for treating HIV infection" comments Associate
Professor Kameoka.
"We
now need to investigate how we can selectively introduce a CRISPR/Cas9
system that targets HIV-1 genes into the infected cells of patients. To safely
and effectively introduce the CRISPR/Cas9 system the vectors must be improved.
We hope this research will provide us with useful information in developing a
treatment method that can completely cure the HIV-1 infection."
Source:
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