The CRISPR/Cas9 Genome Editing Method Becoming The New Anti-HIV Therapy

The current HIV treatment (ART) has been a huge success because of its ability to halt progression to AIDS in infected persons and because it has been able to reduce transmission risks. Despite that ART hasn’t been able to eliminate HIV-1 from dormant infected T-cells yet. Therefore, a new method of treating HIV is needed.

Previous findings and research outcomes derived from the so-called “shock and kill” method have shown that the HIV curing method requires a strategy that directly eliminates the pro-viral DNA sequences from the majority of HIV-1 infected cells including cells that act as the main host cells to the HIV virus and protect cells from future infection without causing serious harm to the host. Research has shown that CRISPR/Cas9 genome editing, based on the adaptive immune system of bacteria could be used to cure HIV in a really efficient way.

Recently, our ability to edit the DNA of humans has been improved by a new gene editing method. This method called CRISPR is based on the working of the adaptive immune system of bacteria used to protect themselves from virus induced infections. When a bacterium survives a virus attack, the bacterium is able to produce RNA that matches the DNA sequence of the virus that invaded the bacterium. This RNA forms a complex with a protein called Cas9 which is able to cut DNA. When the Cas9 protein finds a match to the virus DNA within the DNA sequence of the bacterium, the protein is activated and cuts out the virus DNA. Researchers studying the working of this process concluded that the Cas9 protein could be engineered in a way that it is able to cut out not just viral DNA but any DNA sequence at a precisely chosen location. That’s why researchers have been developing ways to use this CRISPR/Cas9 mechanism in living human cells, so it could be used to cure diseases.

In 2015, scientists used the CRISPR method to cut out the HIV virus in living cells of patients. A year later they carried out a large-scale project with HIV infected rats that had the HIV virus in all of their body cells (Bella et al. , 2018). By applying the CRISPR method to these rats, the researchers were able to remove 50 percent of the HIV infected cells out of the rat’s bodies. The current anti-HIV therapies do not completely eliminate the virus, therefore require a lifelong application. The CRISPR/Cas9 method could be a potential way of curing HIV in a much more efficient way than ever before. This review will zoom in on the technical aspects, the societal relevance and the future prospect of CRISPR/Cas9 genome editing to illustrate what role the CRISPR/cas9 genome editing method can play in finding a way to cure HIV. A cure is needed AIDS is a major problem when it comes to public health. Worldwide, over 35 million people are infected by the HIV-1 virus and this number is growing with an amount of 2 million people per year.

The current HIV treatment called ART is able to effectively control viremia in all HIV-1 patients and reestablishes the main host cells of the virus (CD4+ T-Cells). Nevertheless, this treatment hasn’t been able to eliminate HIV-1 from dormant infected T-cells yet. In these cells, the pro-viral duplicated DNA segments persist in an inactive state but when reactivated, they produce replication-competent virus. With a quick viral ricochet upon disruption of antiretroviral treatment (ART) as a result. This is the reason that HIV patients must maintain with life-long antiretroviral treatment. Current attempts to eliminate HIV-1 from this particular cell pool have been using the “shock and kill” method, with the idea that persuading HIV reactivation in CD4+ memory T-cells may trigger virus-producing cell elimination by either cytolysis or host immune responses. However, there are a couple restrictions to this approach. For example, if a significant portion of HIV genomes in this pool is non-functional, not all incorporated pro-virus can produce replication-competent virus. This and numerous other observations propose that a strategy to cure HIV should be working with methods that directly eliminate the pro-viral genome from the majority of HIV-1-positive cells, including CD4+ T-cells and protect cells from future infection without causing serious harm to the host. A new approach is needed for the achievement of enduring reduction of the virus, allowing HIV-1 patients to halt ART and decrease the associated costs and possible long-term side effects that come along with the anti-retroviral treatment.

From bacterial immune system to HIV cureNow we’ve looked at and understand the working of CRISPR-Cas9 and know the problems of the current HIV curing strategy the question is; how is cirspr-Cas9 genome editing supposed to help at these fronts? The recent results designate that the CRISPR-Cas9 adaptive immune mechanism used by bacteria could be modified into an anti-virus device that will work in human cells. The CRISPR/Cas9 method is suitable for targeting the viral coding or non-coding regions during either pre-integration or provirus stages. When DNA double stranded breaks (DSB’s) are shaped by CRISPR/Cas9, exonucleases within the host cells will damage the viral DNA sequences nearby the DSBs, due to an absence of security from the non-coding long terminal (LTR) sequence or LTR-binding proteins in the broken ends. Meanwhile, targeting the coding sequences can inactivate viral genes through mutations, insertions or deletions. In contrast, targeting the non-coding regions causes structural disturbance and can be persuaded in a pre-integration stage while the pro-viral genome excision can be accomplished in either the pre-integration stage or in the pro-virus stage. This means that there are different targeting strategies that may work in different stages of the HIV-infection which increases the chance of effectively curing HIV. Without regard to the stage or region that is being targeted, recent studies also indicate a substantial decrease of viral expression by Cas9-mediated anti-viral immunity which is really important when it comes to finding a well-working cure. Operating the CRISPR/Cas9 method against multiple conserved target sequences concurrently can minimalize the growing concern of viral variants emerging resistance to singly guided CRISPR/Cas9.

Additionally, applying the steadily expressed CRISPR/Cas9 system into a T-cell line resulted in long-term protection against HIV-1 infection. With all of these promising findings, CRISPR/Cas9 has a serious chance of becoming an effective anti-HIV therapy. Discussion It has become clear that the quite efficient and successful ART treatment is not able to permanently eliminate HIV-1 from infected cells therefore requires a life-long treatment for patients. This is the reason another way of treatment is necessary so permanent remission can be accomplished allowing HIV infected people to stop ART which lowers costs and the chance of negative side-effects. Working with the CRISPR/Cas9 method results in the fact that not only the HIV-1 infected cells will have the viral DNA cut out, but also the majority of healthy cells will build resistance against HIV infection.

Hereby, the CRISPR/Cas9 method is able to completely eliminate the HIV-virus which is a revolutionary and promising step in the right direction to finding a cure for HIV. Despite all these findings, there are still some obstacles that must be overcome in order to implement the CRISPR/Cas9 method. For example, elimination of viral sequences must be maximized which will require additional analysis of the HIV-1 infected cells harbored by patients’ CD4+ T-cells. Besides that, CRISPRs have to get suitable and personalized for patients. Another important point is that the CRISPR/Cas9 delivery must be improved in order to target the majority of T-cells. with these developments as future prospects and our current knowledge It becomes clear that CRISPR/Cas9 actually can play a significant role in the run-up to finding an effective way to cure HIV.