Tuesday, October 25, 2016

CRISPR in the fight against human viruses

The CRISPR/Cas system is naturally occurring in bacterial immune systems as a defense mechanism against virus attacks. Recent breakthroughs in CRISPR technology as an accessible, adaptable, and precise genetic engineering tool (using guide RNA to facilitate the degradation of specific nucleic acids) has found many potential applications to human diseases. 

The CRISPR immune system protects against viral attacks through three main steps: 
  1. Adaptation – DNA of the invading virus is incorporated into the CRISPR sequence
  2. Synthesis of CRISPR RNA –  The CRISPR sequence is transcribed to create small RNAs that function like a genetic GPS, guiding proteins (Cas9) to a specific target. 
  3. Targeting – A set of enzymes called Cas9 (CRISPR-associated protein) precisely cuts DNA and slices out invading viruses. 
CRISPR/Cas 9 has already been applied to four human viruses: HIV-1, Epstein-Barr virus, Hepatitis B virus, and Human Papillomaviruses HPV16 and HPV18. 

While there are still many barriers to overcome before application to the clinic will become reality, basic research studies in viral transduction with lentiviral or adenoviral vectors have been employed. In the future, scientists expect to see important clinical applications of this new gene-editing technology to treat viral infections, cancers, and genetic diseases. 

Source: White MK, Hu W, Khalili K. The CRISPR/Cas9 genome editing methodology as a weapon against human viruses. Discovery medicine. 2015;19(105):255-262. 

- Linda Shin 

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