BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: human gene editing

HIV Adapts to CRISPR-Cas9 Treatment

There has been an abundance of research using CRISPR/Cas9 gene editing to search for a cure for HIV. The HIV virus enters immune cells and uses the host cell’s method of replication to replicate the viral genome. With CRISPR/Cas9, specific mutations can be introduced in order to make it more challenging for the HIV virus to enter Helper T-Cells. Guided by specific strands of RNA, the Cas9 enzyme can cut a particular piece of the viral genome out, rendering it useless.

When a team of researchers at McGill University attempted to use the CRISPR method to disable the HIV viral genome, they found a major roadblock. Two weeks after the CRISPR/Cas9 treatment, the host cells appeared to be creating copies of the virus. This may be attributed to an error in the enzymes that copy the viral DNA, causing a change in the genome, and a mutation that allows it to evade the CRISPR treatment. However, the McGill researchers believe that this mutation was a result of the CRISPR treatment itself.

After DNA is cut by the Cas9 enzyme, the host cell usually attempts to repair the damage. Occasionally, this results in the addition or deletion of a few nitrogenous bases. While these changes usually result in the inactivation of the cut gene, sometimes they don’t. The active cut DNA is no longer recognized by the machinery used to prevent HIV infection of the cell, and the mutated viral genome is resistant to the usual methods of disablement.

More researchers at the University of Amsterdam had similar results in their research. While it is not that surprising that HIV can overcome the CRISPR/Cas9 gene editing at some point, the leader of the research (Atze Das) said “What is surprising is the speed- how fast it goes”.

If CRISPR was used at the same time as HIV-attacking drugs (inhibitors of protease, reverse transcriptase, and integrase), perhaps the mutations would be less  detrimental. This roadblock does not mean that a CRISPR cure for HIV is impossible, but it does make it far more challenging to overcome.

The Grey Area of Human Gene Editing

The process of Human Gene Editing developed with the goal to prevent future generations from suffering from genetic diseases present in past generations, like our own. Human gene editing, provided it is done only to the correct disease, alters the DNA in embryos, eggs, and sperm to the when reproduction occurs, the gene for the disease or disability is not inherited. However, two weeks ago the National Academies of Sciences and Medicine issued a report stating that human gene editing is being used to enhance people’s health or abilities. This is considered unethical according to organizers of a Global Summit on human gene editing.

Human gene editing has been given a “yellow light” because the process is not yet approved to be done on people. There are high hopes that diseases caused by only 1 genetic mutation such cystic fibrosis and Huntington’s disease will be eliminated due to this process. Unfortunately diseases that are caused by more than one genetic mutation, such as autism or schizophrenia, are not curable by this process.

National Cancer Institute

Gene Editing on humans is such a controversial topic right now: is it ethical to change genes? should the practice be used to change physical appearances? Ultimately, if Human Gene Editing is approves, who decides when it becomes too much, or unethical. This grey area is presented to be somewhere between when it is appropriate to help aid the life of a human, ridding them of a disease, and when enhancements are made.

 

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