Antiviral CRISPR
CRISPR/Cas13 was programmed to destroy human viruses
The researchers used the CRISPR/Cas13 system as an antiviral and diagnostic tool for RNA viruses. An article about this was published in the journal Molecular Cell (Freije et al., Programmable Inhibition and Detection of RNA Viruses Using Cas13).
Many of the most common and deadly human pathogens in the world are RNA–based viruses - for example, Ebola, Zika and influenza, and most of them do not have regulatory-approved treatments.
"Human viral pathogens are extremely diverse and constantly adapt to the environment, even within the same species, which highlights both the problem and the need for flexible antivirus platforms," says Pardis Sabeti, one of the researchers, an employee of the Howard Hughes Medical Institute. "We have created the CARVER platform (Cas13–Assisted Restriction of Viral Expression and Readout), which has proven to be a powerful and quickly programmable diagnostic and antivirus technology for the treatment of a wide range of viral diseases."
In order to explore new antiviral strategies, the team focused on Cas13, which focuses on viral RNA in bacteria in the natural environment. This protein can be programmed to remove specific ribonucleic acid sequences from viral particles. Despite the small limitations, the method is relatively easy to apply in practice and research in the laboratory.
The team of scientists first tested a set of RNA viruses in search of sequences that Cas13 could effectively remove. First of all, the researchers were looking for segments that are least likely to mutate and most likely turn off the virus when cut.
The researchers experimentally tested the activity of Cas13 in human cells infected with one of three different RNA-based viruses: lymphocytic choriomeningitis virus (LCMV), influenza A virus (IAV) and vesicular stomatitis virus (VSV). They injected the Cas13 gene and guide RNA into the cells, and 24 hours later exposed the samples to the virus. After another 24 hours, Cas13 enzymes reduced the level of viral RNA in cell cultures by up to 40 times.
The scientists then investigated the effect of Cas13 on viral infectivity–in other words, how much of the remaining virus can actually continue to infect human cells. The data showed that eight hours after exposure to the virus, Cas13 reduced the infectious ability of influenza by more than 300 times.
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