DNA-guided CRISPR-Cas12a system opens path to new antiviral drugs
A University of Washington and Howard Hughes Medical Institute team reports in Nature Biotechnology an inverted CRISPR-Cas12a system that uses a DNA guide to cleave RNA, the first reversal of the classical paradigm, with potential for sharper diagnostic tests and antiviral drugs.
A team of molecular biologists at the University of Washington and the Howard Hughes Medical Institute, led by David Taylor and Jeong-Mok Jung, reported on May 22, 2026 in Nature Biotechnology a new CRISPR system that reverses the classical Cas12a paradigm.
Instead of using an RNA guide to find and cut DNA, the engineered enzyme uses a DNA molecule as a guide and cleaves RNA target sequences. It is the first time that this inversion of the basic CRISPR mechanism has been demonstrated at the level of structural biology and confirmed in laboratory tests against viral RNA targets.
Why the inversion matters
CRISPR-Cas technology earned the 2020 Nobel Prize in chemistry for Emmanuelle Charpentier and Jennifer Doudna. Since then the field has split into two main branches:
- Therapeutic, which produced the first approved CRISPR drugs for sickle cell anaemia in 2024.
- Diagnostic, which gave us rapid tests such as SHERLOCK and DETECTR used for virus detection, including SARS-CoV-2.
The paradigm inversion achieved by Taylor’s group could advance both fields. The same enzyme can now be used to detect and degrade viral RNA inside cells, something existing RNA-guided systems could not do with the same efficiency.
Methodology
The team modified the natural Cas12a enzyme from the bacterium Acidaminococcus sp. Mutations were introduced into two key domains that recognise the guide and the target sequence. Structural characterisation was done by cryo-electron microscopy at 2.8 angstroms resolution, allowing a precise reconstruction of how the DNA guide contacts the target RNA.
In tests against synthetic viral sequences the modified enzyme showed:
- sensitivity at femtomolar concentrations, comparable to the best existing RNA-guided Cas13 systems
- substantially lower off-target cleavage of non-target sequences
- high selectivity even with short synthetic target RNA molecules
What the study does NOT show
Taylor stresses that the result should not be read as a finished antiviral therapy:
The tests were carried out in isolated biochemical conditions and in cell culture. At least five years of systematic research, including animal models and the development of effective delivery systems for the enzyme, will be needed before clinical trials in humans can even be considered.
Delivery of the modified enzyme into virus-infected cells is a separate problem and remains unsolved at the current stage.
A second limit is that the inverted system currently works only with short synthetic target RNA molecules. Most viral RNA molecules have secondary structure that can block enzyme access. Future research will focus on enzyme variants able to recognise structured regions of viral genomes, a much harder technical problem.
The team is already working with Sherlock Biosciences to apply the result in the next generation of diagnostic tests.
Relevance for the local research community
The discovery is interesting because it enables cheaper and more accurate diagnostic tests usable in public health networks. The Torlak Institute in Belgrade has been developing molecular tests for viral infections for several years. Partnerships with international laboratories of this kind could bring technological leaps without requiring local production of engineered enzymes.
Will CRISPR become a standard tool in clinical diagnostics over the next decade?
Share your view: where should more resources go, into therapeutic or into diagnostic CRISPR applications? Tell us in the comments.
