CRISPR is a form of gene editing that has revolutionised genetics. Previously, creating genetically modified organisms took a considerable amount of time and money. CRISPR has changed that, with the potential to revolutionise medicine.
What is CRISPR?
CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeats, was originally used by bacteria to defend themselves from bacteriophages – another topic that deserves its own article. Bacteriophages use bacteria to reproduce and are generally successful in this. However, in the rare case a bacterium survives a bacteriophage invasion, it stores some of the bacteriophages DNA in its own DNA archive, called CRISPR. This allows the bacteria to defend itself from another bacteriophage invasion – enzymes find the DNA from the previous bacteriophages and creates an RNA copy, which is then delivered to a cas9 protein.
The protein cas9 is instrumental to the CRISPR revolution. Once the cas9 protein has received the RNA copy, it scans the bacterium for a match, by comparing all other DNA it can find. Once it has found a perfect match, it surgically cuts out the bacteriophages DNA, rendering it entirely useless. Cas9 is special, as it is remarkably precise at what it does.
The CRISPR revolution started when scientists discovered the CRISPR system was programmable, and it worked in every cell, from prokaryotes to eukaryotes alike. You are able to give it a copy of DNA you would like to modify, and insert it into a living cell. This is remarkable. CRISPR gives scientists the ability to modify living cells – switch genes on and off, and target specific genes. This opens many doors for CRISPR; it could spell the end of certain diseases, like HIV, cancer and, yes, malaria.
In a test performed using rats who has the HIV virus in 99% of their body cells, a simple injection of CRISPR cut the HIV virus population by a factor of two. The same goes for cancer. Cancer cells divide rapidly and refuse to die, all while evading the watch of the human immune system. This can be kerbed using CRISPR to edit immune cells to make them much more adept at finding, and killing defective cancer cells.
The End of Malaria?
There are many proposed uses for CRISPR in the field of malaria. Perhaps the most interesting is the use of it in the vector – mosquitoes. CRISPR can be used to insert genes which make the mosquitoes immune to the malaria plasmodium, which uses mosquitoes as a vector to infect human hosts. This has performed well in lab tests, proving the mosquitoes are immune to the malaria plasmodium. Another use for CRISPR is removing the ability for female mosquitoes to fly. The malaria plasmodium is spread solely by female Anopheles mosquitoes. Using CRISPR to insert a gene into these mosquitoes that renders females unable to fly is a valid way of eradicating malaria. Males of the species will still retain the ability to fly, and thus mate with other female mosquitoes, unwittingly making more females of the population unable to fly and thus spread the disease. Unfortunately, uses such as these have a slew of ethical concerns that would take too long to discuss in this article. For now, CRISPR remains a tool that could have great uses but is still in its infancy. For now, the best way of combating malaria is education on the disease in the Sub-Saharan African countries that are affected the most.