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RNA Vaccine for Rabies Found Safe, Generates Antibodies

Raccoon
(edbo23, Pixabay)

26 July 2017. A vaccine to prevent rabies made from messenger RNA, genetic material transcribed from DNA, was shown in a clinical trial to be generally safe and able under some conditions to induce antibodies. Results of the study, conducted by CureVac AG in Tübingen, Germany, appear in yesterday’s issue of the journal The Lancet (paid subscription required).

Rabies is a life-threatening viral disease often transmitted through the bites of rabid wild animals, such as raccoons, foxes, or bats. The virus infects the nervous system, eventually reaching the brain, beginning with fever, headache, and general weakness. Symptoms generally worsen as the disease progresses, leading to insomnia, anxiety, paralysis, hallucinations, and death within days after advanced symptoms appear.

CureVac’s technology adapts messenger RNA, nucleic acids related to DNA that leave the cell nucleus and go to cells’ protein-making components. Those cell components synthesize human proteins by reading and translating the genetic code in messenger RNA into the appropriate amino acids for that protein. The company’s platform is based on research by Ingmar Hoerr in the 1990s, one of CureVac’s founders, who discovered a way of controlling RNA that was previously considered too unstable for use as a treatment or vaccine.

The early-stage clinical trial tested CureVac’s experimental glycoprotein vaccine to prevent rabies, code-named CV7201, given as an injection. The study tested CV7201 among 101 healthy adults in Munich, looking primarily at the safety of the vaccine, but also its ability to generate antibodies in the blood. Participants in the study received doses between 80 and 640 micrograms given 2 or 3 times, over 28 to 56 days. Injection methods tested were under the skin or into the muscles, using a syringe or needle-free high-pressure jet.

The results show the vaccine was generally safe and well-tolerated by participants, with a few adverse effects reported. Most participants — from 78 to 97 percent, depending on the administration method — experienced some form of mild injection-site reactions. However, nearly 8 on 10 (78%) of individuals receiving intramuscular injections reported systemic reactions, with 10 of those reactions graded as severe.

Injections given by needle-free devices appeared to generate the greatest numbers of rabies antibodies, particularly when given under the skin. After 1 year, more than half (57%) of participants receiving a booster of 80 micrograms with needle-free injections under the skin also generated measurable antibodies.

The company says the trial is the first study with humans of a preventive vaccine made from messenger RNA. World Health Organization assigned the generic name nadorameran for CV7201. WHO gives unique nonproprietary names to generic drugs, including biologics, to encourage standardization, with nadorameran as the first in its class of immunological agents derived from messenger RNA.

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