CRISPR Variant Produces Tuberculosis-Resistant Cows

• A team of researchers from China has successfully utilized an innovative form of the genome-editing technique CRISPR to insert a new gene into the cow genome, rendering the animals much more resistant to tuberculosis.
• CRISPR/Cas9n is used to successfully insert a tuberculosis resistance gene into the cow genome.

About this study:

• In this study, the investigators inserted the NRAMP1 gene into the genome of bovine fetal fibroblasts—cells derived from female dairy cows—using the CRISPR/Cas9n technology. These cells were then used as donor cells in a process called somatic cell nuclear transfer (therapeutic cloning), where the nucleus of a donor cell carrying the new gene is inserted into an egg cell, known as an ovum, from a female cow.
• Next, the ova were nurtured in the lab into embryos before being transferred into mother cows for a normal pregnancy cycle. As a control, the experiments were also conducted using the standard CRISPR/Cas9 technology as a comparison. A total of 11 calves with new genes inserted using CRISPR were able to be assessed for resistance to tuberculosis and any off-target genetic effects.
• Genetic analysis of the calves revealed that NRAMP1 had successfully integrated into the genetic code at the targeted region in all of the calves. None of the calves that had the gene inserted using the new CRISPR/Cas9n technology had any detectable off-target effects, whereas all of the calves with the gene inserted with previously used techniques for CRISPR/Cas9 did.
• Remarkably, when the calves were exposed to Mycobacterium bovis, the bacterium that causes bovine tuberculosis, the researchers found that transgenic animals showed an increased resistance to the bacterium measured by standard markers of infection in a blood sample. Additionally, they found that white blood cells taken from the calves were much more resistant to M. bovis exposure in laboratory tests.

About CRISPRs (Clustered Regularly Interspersed Short Palindromic Repeats)

• CRISPRs are elements of an ancient system that protects bacteria and other single-celled organisms from viruses, acquiring immunity to them by incorporating genetic elements from the virus invaders.
• CRISPRs evolved over millions of years to trim pieces of genetic information from one genome and insert it into another. And this bacterial antiviral defense serves as an astonishingly cheap, simple, elegant way to quickly edit the DNA of any organism in the lab.
• Discovery of CRISPRs has changed gene therapy. CRISPRs work by using an enzyme — Cas9 — that homes in on a specific location in a strand of DNA. The process then edits the DNA to either remove unwanted sequences or insert payload sequences. CRISPRs use an RNA molecule as a guide to the DNA

Analysis(On gene editing):

• Major risk from gene editing is 'off-target' side effects. once you put a CRISPR gene editing "tool" into a person's body, it can travel throughout the body and might get into other cells that you're not targeting
• Gene editing technologies are costly and patients who might benefit from them would not have access to this.No doubt CRISPR is cheaper than any other methos but still it is not affordable to all.
• Changing human DNA creates, for scientists and humanity, a frightening ethical grey zone.
• In the hands of evil biohackers, these powerful and simple tools are a cause for alarm. A smart biohacker could alter the influenza genome, for example, to make it more potent, setting off an epidemic that kills hundreds of millions of people.
• The government does not have any regulations on editing human DNA.
• But on the positive side, For the many millions of poor souls suffering from diseases arising from genetic defects, CRISPR and the research it fuels could mean finding a cure for their problem in their lifetimes.
• It would be “irresponsible” to use a new gene-editing technique on human embryo, sperm or egg cells until questions of safety are addressed and there is “broad societal consensus” on the purpose of the effort.

By: Vishal