CRISPR-Cas9 is a technology that has hit the headlines in recent years and understandably. Researchers who have the ability to change an organism's DNA are a controversial topic. Last year, a Chinese scientist claimed that it made the world's first ever redesigned babies using the technology.
But this technology can also have positive effects. Much more recently, US scientists published a paper showing the removal of HIV from live mice for the first time using two technologies, one of which is CRISPR-Cas9.
But where does CRISPR-Cas9 come from and how exactly can researchers use it to cure genetic diseases?
DNA carries genetic instructions for all living things. It consists of two wires that coil around each other, and each string consists of molecules known as nucleotides. The sequence of these nucleotides acts as a code or a drawing for the formation of proteins, something that is crucial to all living things.
Where does CRISPR-Cas9 come from?
Bacteria use CRISPR and Cas9, two different components that work together to defend themselves.
CRISPR is found in bacteria and other single cell organisms, but not in humans. It is a term used for sequences of nucleotides that are palindromic and repetitive. First discovered in 1
To reproduce, a virus must replicate its DNA, but it cannot on its own. It needs an ignorant accomplice. It is necessary to hijack a cell machine, spark a path to destruction for its host. When a virus attacks a bacterium, it inserts pieces of its own DNA into the bacteria. Unobtrusively, the bacteria's own protein-making machines will now make viral proteins. Viral proteins are now present in the bacteria and they begin to reproduce and collect and kill the bacteria.
But there is a way to stop this. A bacterium that has survived a virus attack puts a mechanism in place to save itself the next time another attack occurs. The bacteria pick up pieces of viral DNA that have entered the cell and integrate it into its own DNA. These pieces of DNA are then stored between the CRISPR repeats.
The bacteria then create a "most desired poster" in the form of RNA. This poster is incorporated into the Cas9 protein, which acts as a killer employed by the bacteria to end a virus. When Cas9 recognizes that a DNA from an invading virus matches the sequence of the "most sought-after poster", it chops into the DNA of the invading virus and kills it.
How can CRISPR-Cas9 be used in editing?  We all know scientists are wise, but they have ideas for DNA editing from organisms that have much fewer cells than they do – bacteria. They copied this whole process that we talked about.
They choose the culprit, create a most sought after poster, remove the suspect from Cas9, and change the gene so that in the case of HIV, the virus can be completely eliminated from the host.
This process can also be used for diseases that are not caused by viruses and can exist in our own DNA, such as Huntington's disease and hemophilia.