17 December 2019

CRISPR against antibiotic resistance

Using the powerful CRISPR gene editing tool, scientists from the University of California at San Diego are working to solve one of the most formidable problems for human health - antibiotic resistance. A research team led by Andres Valderrama and Surashri Kulkarni has developed a new system that significantly increases the effects of inactivation of a gene that makes bacteria resistant to antibiotics. The new system, based on the technology of "active genetics" developed by biologists of the University of California for insects and mammals, is aimed at genetic inheritance of preferred traits.

The widespread use of antibiotics and their use in the production of animal feed has led to an increase in antimicrobial resistance in the environment. These sources of antibiotic resistance are transmitted to pathogens that are dangerous to humans and contribute to the health crisis associated with a sharp increase in the number of drug-resistant bacterial strains. Health experts predict that antibiotic resistance could increase dramatically in the coming decades and lead to 10 million deaths per year from infectious diseases by 2050.


The genes that confer antibiotic resistance in bacteria (blue arrow) are often found on ring chromosomal elements – plasmids. Site-specific clipping of these plasmids using the CRISPR system, which leads to the destruction of the plasmid, led to a decrease in the incidence of resistant infections by about 100 times. The Pro-Active Genetics (Pro-AG) system uses a highly efficient cut-and-paste mechanism that inserts a gene cassette (red rectangle) directly into the gene that leads to resistance, thereby disrupting its function. The Pro-AG donor cassette is surrounded by sequences corresponding to its purpose (blue rectangles) to initiate the process. After insertion into the target gene, the Pro-AG element copies itself through self-amplification, resulting in a decrease in the number of antibiotic-resistant bacteria by 100 thousand times.

The "proactive" genetic system (Pro-AG) is based on the modified standard gene editing technology CRISPR-Cas9. Researchers have developed a Pro-AG method, working with E. coli (Escherichia coli), to disrupt the function of a bacterial gene that provides resistance to antibiotics. In particular, the Pro-AG system combats antibiotic resistance genes located in plasmids – ring DNA that can replicate independently of the bacterial genome. Multiple copies – "amplified" plasmids carrying antibiotic-resistant genes can exist in each cell and have the ability to transmit antibiotic resistance to other bacteria, which makes successful treatment impossible. Pro-AG works by the "cut and paste" mechanism and disrupts the activity of the resistance gene with an efficiency at least two orders of magnitude greater than modern editing methods.

The researchers demonstrated the effectiveness of the new technique in experimental cultures containing a large number of plasmids with genes of resistance to the antibiotic ampicillin. The result of Pro-AG editing is the insertion of specialized genetic data into target sites with high accuracy.

Although Pro-AG is not yet ready for use in patients, in the future it can be used to treat conditions such as cystic fibrosis, chronic urinary tract infections, tuberculosis and infections associated with resistant biofilms that create complex problems in a hospital setting. Scientists claim that the technology can also be very effective for removing antibiotic-resistant strains from the environment – in sewers, fish ponds and feeding grounds. Since Pro-AG "edits" its targets rather than destroying them, this system also allows you to create or manage bacteria for a wide range of future biotechnological and biomedical purposes, making them harmless, or even programming them to perform useful functions.

Article by J.A.Valderrama et al. A bacterial gene-drive system efficiently edits and inactivates a high copy number antibiotic resistance locus published in the journal Nature Communications.

Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru Based on UC San Diego News Center: New CRISPR-based Gene-Drive System in Bacteria Defeats Antibiotic Resistance.

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