What the study found
In a study published in Science Translational Medicine, researchers at the University of Virginia gave K-9 for two weeks after symptoms appeared in mice. They reported that neurological decline was halted and measures of vision and movement improved. Comparison groups, including mice given a standard MS drug, did not show similar recovery.
K-9 is an experimental compound derived from a class of antivirals used to treat HIV and hepatitis B. It targets an immune mechanism called the inflammasome. In mice, the researchers reported protection of nerve fibers and myelin, as well as a lower rise in the blood marker neurofilament light chain (NfL).
What the human data can tell us
The paper also examined insurance records from three U.S. patient groups, covering more than 3 million people. Use of nucleoside reverse transcriptase inhibitors (NRTIs) for HIV or hepatitis B was associated with lower rates of MS diagnoses and relapses. This observational association does not show that the drugs prevent MS; differences between patients or other factors could explain it.
No clinical trial has yet shown whether K-9 works for MS in people. The findings support further research, not a treatment recommendation. K-9 should not be treated as interchangeable with existing HIV medicines.
Evidence and limitations
The treatment results come from animal models, while the human analysis is observational. Both have limits and cannot establish clinical benefit. Further laboratory work and carefully designed human trials would be needed to determine safety and efficacy.
Sources
- U.S. National Institutes of Health, Sept. 23, 2026
- Yerramothu et al., Science Translational Medicine, DOI: 10.1126/scitranslmed.aei2870
Published in Science Translational Medicine (Yerramothu et al.), DOI 10.1126/scitranslmed.aei2870, NIH-supported, University of Virginia team; the insurance-record analysis covering 3M+ people and the mouse treatment protocol are stated in the study as cited.
The exact magnitude of the reported neurofilament light chain (NfL) reduction is not given as a specific figure, only described as 'lower'; the insurance-record association is explicitly observational, which the article itself flags as not proving prevention.
The exact number of mice in the treatment and comparison groups is not stated in the article; no human clinical trial of K-9 has started or been scheduled; response from the contacted institution not yet received.