By Michael Haederle

A Shot at Blocking Addiction

UNM Researchers Work to Create an Opioid Vaccine

New help may lie on the horizon to help people struggling with opioid use disorder beat their illness.

With the help of a $250,000 grant from the National Institutes of Health, University of New Mexico researchers are developing a vaccine that would block opioids from acting in the brain, a treatment that could play a key role in overcoming addiction.

Kathryn Frietze, PhD, an assistant professor in UNM's Department of Molecular Genetics and Microbiology and a KL2 scholar in the Clinical & Translational Science Center, plans to attach molecules of different opioid drugs, such as hydrocodone or oxycodone, to the surface of a harmless viruslike particle (one derived from viruses that infect bacteria).

The particles - VLPs for short - are viruses that have their genomes removed, leaving only their outer protein shell. Lacking a genome, they're unable to reproduce, but the body's immune system still recognizes them as foreign invaders and manufactures antibodies to attack them and the drugs attached to their surface.

If the method works as planned, the antibodies would be primed to attack a similar opioid ingested or injected into the body, blocking the drug from reaching opioid receptors in the brain, thus preventing the expected high.

"Other researchers have taken opioid drugs and tried to make immune responses to them by attaching them to proteins like tetanus toxoid," Fritze says. But those methods require multiple injections and don't last long, she says.

Frietze hopes the method she's developing together with colleague Bryce Chackerian, PhD, will require only a single inoculation and produce a stronger and longer-lasting immune response.

Chemist Naomi Lee, a researcher at Northern Arizona University, is collaborating with the pair to modify various opioid molecules so that they can be attached to the surface of the VLPs, Frietze says. Lee is focusing on hydrocodone, oxycodone and hydromorphone, Frietze says, but future research might also include fentanyl and heroin.

Blunting an opioid drug's intoxicating effects on the brain "would not be a standalone treatment," Frietze says, but it could be used in conjunction with counseling and perhaps other forms of medication-assisted treatment to help people quit using and stay clean.

A potential advantage of a vaccine over other treatments is that it might only need to be administered a few times and could drive a robust immune response that could stay active in the body over a period of months.

In addition, Frietze says, vaccines of this type are relatively inexpensive to manufacture and don't require refrigeration to keep them stable, which could be of benefit in a developing country, for example.

In this first, year-long phase of the research Frietze expects to test the strength, speed and duration of the immune response in mice. Future studies will evaluate how effective the vaccine is in blocking the opioids from reaching the brain.

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