Even though therapies such as ‘Antiretroviral (ARV)’ has been quite effective against HIV-1. However, the virus remains dormant in the cells of an infected individual after even taking Antiretroviral (ARV) drugs.
And again, start replication and weaken the immune system soon after therapy termination.
Therefore, scientists looking for other strategies to cure HIV. Moreover, they drew attention to some radical approaches, and that’s utilizing CRISPR mediate gene therapy to target infected cells and eliminate HIV genes out of it.
The CRISPR technology renewed hope in the scientific community as a possible alternative therapy to remove HIV from the infected cells.
What Is AIDS/HIV?
AIDs (acquired immune deficiency syndrome) is a disease caused by a virus called Human immunodeficiency virus or HIV. AIDS is the last and most severe stage of HIV infection.
HIV can integrate its genome into the host cells and destroying white blood cells (CD4+ T cells). Hence, collapse the immune system, making the infected individuals vulnerable to various diseases.
Usually, the infections are quickly encountered and eliminated by the body defense system without even noticing.
While in the case of AIDS, the immune system compromise to such an extent that It cannot fight back against common viral and bacterial infections.
Why AIDs Is Dangerous & Incurable?
What makes AIDS so dangerous is the fact that it can hide from the body defense system – Immune system.
With the help of reverse transcriptase, HIV first converts its genome into double-strand DNA. This helps the survival of viral DNA in the infected cells.
HIV targets different immune cells and uses them to spread the infection throughout the body.
In the early stages, HIV multiplies very rapidly. Later, it slows down and remains hidden from the body defense system for years. During which it gradually replicates and further weaken the system.
Problems With Current Approaches to Cure HIV
Currently, various Antiretroviral (ARV) drugs are mostly used in combinations. These drugs involve the HIV replication process by targeting the reverse transcription stage.
However, now, after even taking Antiretroviral drugs, HIV doesn’t affect, and thus, AIDS can’t be completely cured.
Other therapy includes ‘Growth Hormone Therapy” help to boost the immune system of HIV patients.
Research has shown that the treatment with this therapy “double the number of the immune cells in the bloodstream of HIV patients”. Hence, help to rebuild the affected immune system.
Thus, the current approaches do not treat/eliminate HIV from patients. Therefore, scientists drew attention by using CRISPR technology.
What basically is CRISPR?
CRISPR is a powerful gene-editing tool that has the potential to edit or delete the genome of almost any organism.
Now, CRISPR technology allows researchers to modify any DNA target more correctly and precisely than ever before.
Moreover, CRISPR mediated therapy promises to revolutionize the medicines sector including the treatment of genetic disorders. The diseases that once considered unsolvable and incurable.
Explore More About CRISPR: What is CRISPR Cas9?
Can CRISPR Cure HIV?
CRISPR could be utilized in several ways to destroy HIV and thus cure AIDS. This happens either by targeting the viral DNA inside the infected cells or by making the cells resistant to HIV.
Researchers conducted several experiments in the cells lines and animal models and have successfully eliminated HIV and AIDS.
The research, published in PNAS, scientists have shown that they explore a new way to eliminate the HIV viral genome from the infected cells.
They did so by using CRISPR Cas9 approach to halt viral genome expression and replication. Moreover, also to activate the immunity of uninfected cells against HIV.
The paper entitled “RNA-directed gene editing specifically eradicates latent and prevents new HIV-1 infection”.
Scientists at Temple University in Philadelphia successfully used CRISPR/Cas9 technology to eradicate HIV-1 from the infected T-cells. Thus, prevent the chances of reinfection.
“Therefore, most HIV-1-infected individuals, even those who respond very well to ART must maintain lifelong ART due to the persistence of HIV-1-infected reservoir cells,” said Kamil Khalili, lead author of the study.
Some reports show that a minor proportion of individuals are naturally immune to HIV infection. That’s because of a mutation in a gene called CCR5. The gene encodes for a surface protein on immune cells that HIV uses as an entrance door and to infect them.
Three independently research study targets this CCR5 gene and by using CRISPR/Cas9 approach to causes mutations and make it resistant.
The First study led by Dr. Kamil Khalili and his colleagues at Temple University in Philadelphia.
Their team uses CRISPR mediate gene editing to mutate the CCR5 gene in the human fetal liver hematopoietic stem/progenitor cells (HSPCs).
Later, the edit HSP cells are transferred into the mice model, and results showed that it could block HIV infection.
The Second study was conducted by Chinese researchers Hu Chen, Hongkui Deng, and their colleagues.
They also followed a CRISPR/Cas9 approach to edit the CCR5 gene in both CD34+ HSPCs.
“One of the advantages of CRISPR is its high efficiency on difficult to transfect cells,” said Hongkui Deng
Third study leader Linos Vandekerckhove of Ghent University, efforts to use CRISPR-Cas9 to target and mutate CCR5 gene. Hence, make immune cells resistant to HIV infection.
A group of researchers from the Kobe University in Japan successfully eliminate regulatory genes of HIV-1 by using CRISPR/Cas9 technology.
The two regulatory genes, Tat and Rev, are responsible for regulating the replication of HIV-1.
By removing these genes, the virus will no longer replicate and increase their number.
The research published in Scientific Reports and entitled “CRISPR/Cas9 system targeting regulatory genes of HIV-1 inhibits viral replication in infected T-cell cultures.”
Another study at the Temple University, the researchers successfully eradicated the viral DNA from the patient peripheral blood mononuclear cells. The PBM cells engraft in the mice spleen.
The mice are then treated with CRISPR/Cas9 delivered through the lentiviral vector. The Cas9 endonuclease excises the target viral DNA.
Moreover, a Chinese scientist, He Jiankui, successfully created first ever genetically engineered babies resistant to HIV-1 named Lulu and Nana. He did so by using CRISPR-Cas9 to knock out the CCR5 gene.
The ongoing clinical trial aims to investigate the use of CRISPR-Cas9 to edit the CCR5 gene in the immune cells of HIV infected individuals. The trials are carrying out by Chen Hu of Affiliated Hospital to Academy of Military Medical Sciences, China.
Moreover, Philadelphia-based Excision BioTherapeutics is also seeking FDA approval to start clinical trials by the end of this year. They aim to use CRISPR technology for the excision of HIV in humans.
CRISPR has shown some promises and positive results to cure HIV in both animal models and cell lines.
In the near future, scientists are optimistic that CRISPR clinical trials could also be allowed in humans. Hopefully, we may see CRISPR based drugs for HIV/AIDS.
Explore More: 11 Diseases CRISPR Technology Could Cure!
Note: The article is updated on April 12, 2020.