NIH researcher’s Sudan virus vaccine protects macaques in challenge
news desk Laugh
a National Institutes of Health A research group with extensive experience studying Ebola virus countermeasures has successfully developed a Sudan virus (SUDV) vaccine based on licensed Ebola virus vaccine (EBOV). SUDV, identified in 1976, is one of four viruses known to cause human Ebola virus disease. The new vaccine, VSV-SUDV, fully protects cynomolgus macaques from a lethal SUDV challenge. The results have been published in the journal Lancet microbe.
SUDV is different from and less common than EBOV, but also fatal. The recent SUV outbreak in Uganda lasting four months and ending on January 11, 2023 caused 142 confirmed cases and 55 deaths. There is no license for a treatment or vaccine for SUDV, although the candidates are undergoing clinical and preclinical trials. One such candidate is VSV-SUDV, developed and tested by scientists at the National Institute of Allergy and Infectious Diseases of the National Institutes of Health in Hamilton, Montana.
The live attenuated vaccine uses genetically modified vesicular stomatitis virus (VSV), an animal virus that primarily affects cattle, expressing the SUDV protein as a single-dose vaccine. Researchers developed VSV-SUDV using technologies that led to Ervebo, the VSV-EBOV vaccine that was approved by the European Medicines Agency and the US Food and Drug Administration in 2019 as the first vaccine to prevent Ebola virus disease. In the current studies, the researchers replaced Ervebo’s major EBOV protein with a similar protein from SUDV.
Next, the researchers tested the safety and efficacy of VSV-SUDV in macaques. The study involved 11 animals, each of which had previously received an EBOV vaccine and then rested for nine months. Six macaques were vaccinated with VSV-SUDV and five control animals were vaccinated with VSV-MARV, a vaccine candidate under development for Marburg virus. After 28 days, during which no adverse effects were seen from the vaccines in the animals, they were challenged with a lethal dose of SUDV. None of the animals inoculated with VSV-SUDV showed any signs of disease, but four of the five control animals showed clinical signs of Sudan virus disease. The surviving control animal, which responded similarly to the vaccinated animals, surprised the scientists, and they are planning additional studies on possible protective immune responses.
The fact that four control animals were infected with the disease indicates that pre-existing immunity against EBOV and VSV-EBOV has a limited effect on protection against SUV. Investigators expect that giving people VSV-SUDV at a dose similar to that of VSV-EBOV (Ervebo) will provide rapid protective immunity to SUV.