We now possess the technology to utilise genetic engineering to eradicate humanity’s deadliest predator. Malaria was responsible for infecting over 200 million people, whilst causing 438 000 deaths in 2015 alone, (World Health Organisation 2016) and is responsible for over a thousand deaths every day, being possibly the single biggest killer of humans in history.
Malaria is transmitted by the female Anopheles mosquito infected with Plasmodium Parasites. There are many Malaria parasites but the major ones that infect humans are P. Malariae, P. Ovale, P. Falciparum and P. Vivax. (Mueller et al., 2007) The female mosquito feeds on a human, injecting Sporozoites into the blood which then enter hepatocytes. The Sporozoites …show more content…
coli. (Ishino et al., 1987) CRISPR are sections of prokaryote DNA with short repeating sections of base sequences, interspaced by foreign Spacer DNA from exposure to a bacteriophage virus. (Marraffini and Sontheimer, 2010)
CRISPR is a natural process that occurs in bacteria as a defence mechanism. Bacteriophages hunt and kill bacteria by inserting their genetic code into the bacteria. This kills the majority of bacteria, however, any survivors capture the Viral DNA which confers an immunity to the bacteria. (Barrangou et al., 2007) This, therefore, means that the bacteria are now immune to that particular virus.
The natural CRISPR process has three stages. The first is Adaptation in which the Viral DNA is acquired and added into CRISPR as spacers. The Viral DNA is recognised by CAS3, a DNA nuclease and ATP-dependent helicase, (Sinkunas et al., 2011) the spacer is processed and the strands inserted. The second stage is Expression. CAS genes, such as CAS3, are expressed and the CRISPR is transcribed as pre-CRISPR RNA (crRNA) Mature crRNA is then derived from the pre-crRNA. The final stage is Interference in which the target is recognised and destroyed by crRNA and CAS proteins. (Rath et al., …show more content…
The key steps of CRISPR-CAS immunity (Rath et al., 2015)
The natural process of CRISPR: Adaptation – acquisition of spacer from target chromosome, Expression – transcription of pre-crRNA from which mature crRNA is derived. and Interference – CAS proteins and crRNA are used to destroyed invading cells that have been recognised.
The technology used is the Type ii CRISPR system which consists of two main components. The aforementioned CAS9 enzyme along with a section of guide RNA (gRNA) The gRNA contains two RNAs called CRISPR RNA (crRNA) and trans-activating crRNA which are combined together. Single strand guide RNA can be manufactured and is known as synthetic single guide RNA (sgRNA). sgRNA ‘guides’ CAS9 to the target protospacer sequence that matches the sequence within the sgRNA. Protospacer-Adjacent Motifs (PAM), which are 2 to 6 base pair sequences, follow the sequence targeted by Cas9 and must be present else Cas9 cannot bind to the