Monday, April 11, 2016

HIV Defeats Gene Editing Attack By CRISPR

A scanning electron microscope image showing HIV attacking a T cell.

Researchers have conducted over a dozen studies to investigate the ability of CRISPR- Cas9 to conquer the human immunodeficiency virus. Scientists use CRISPR-Cas9  as a gene editing technique that targets a specific genetic sequence and edits the DNA at precise locations. Some researchers have used this technique in two different ways to tackle HIV. One way involves editing the genes made by T- cells so that HIV has no way of attacking the T cell. Another way involves modifying the genes of the T cells with gene- editing tools so they are able to wipe out HIV when it tries to attack them. Researchers at McGill University in Montreal decided to take the second approach and provided T cells with gene editing tools so they can demolish HIV. However, after a couple weeks the group of researchers found that the T cells were rapidly developing copies of the virus that escaped from the CRISPR attack. The researchers were able to identify through DNA sequencing that the virus had developed genetic mutations that were very similar sequences to the CRISPR- Cas9 enzyme. This result was no surprise to the team of researchers because HIV has evolved to a point where it is capable of resisting anti- viral drugs and is adaptable to genetic mutations. The virologist in charge of the team, Chen Liang, proposed that the cause of this genetic mutation happened when the Cas9 enzyme cut the viral DNA. Liang explains that when the DNA is cut, its host cell attempts to repair the break and while doing so a deletion or insertion in the DNA sequence occurs and the CRISPR usually inactivates the gene that was cut. Sometimes the CRISPR doesn't always work correctly and the insertion or deletion of bases made by the T cell machinery allows them to leave the genome of HIV with the capability of replicating and infecting other cells. The worst part about this situation is the fact that T cells machinery cannot detect virus because of the change in its genetic sequence which allows the virus to be resistant to future attacks. However, Liang and molecular biologist Atze Das believe that this issue can be fixed by either inactivating several HIV genes at once or use CRISPR with HIV attacking drugs.

With the help of other advanced gene editing technologies, I think that researchers will be able to eventually detect at least one or two specific mutations within HIV's genetic sequences and find or create a drug most suitable for that mutation. This of course would take years to work out since viral DNA is constantly evolving and able to adapt to genetic mutations very easily making it resistant to many drugs. If researchers can figure out a way to somehow alter  the machinery of T cells so that they are able to overcome invading HIV then treatment for HIV would be more effective for some individuals, maybe not all, but it would be a good start. 

No comments:

Post a Comment