Texas researchers improve Rift Valley vaccine

The Rift Valley fever virus usually affects livestock, causing abortions and deaths in newborn animals, but it can also be passed to humans (zoonosis). An experimental vaccine is in development--a live attenuated strain of the virus, known as MP-12--but this has not completed early clinical trials, partly because of concerns that it could still cause disease (virulence). Researchers from University of Texas Medical Branch are developing an improved version that could make an impact against this growing disease.

According to the WHO, infections in humans are usually mild, with flu-like symptoms, but it can lead to eye disease and blindness, meningoencephalitis (inflammation of the brain and the membranes around the brain) or hemorrhagic fever (causing severe bleeding). As the climates change around the world and the range of mosquitoes gets wider, there is a risk that diseases like Rift Valley fever could spread to Europe and affect both humans and animals.

"If Rift Valley fever virus were introduced to the U.S. or Europe, it would be a very scary situation," said UTMB assistant professor and Sealy Center for Vaccine Development member Tetsuro Ikegami, lead author of a paper on the vaccine work now online in the Journal of Virology. "To be ready to respond, we want a vaccine that can raise immune response very quickly in large animals and health workers. We also want a vaccine that will allow us to differentiate between infected and vaccinated animals."

The researchers from UTMB have tweaked the genome of MP-12, making it less virulent and more effective in mice, and giving it an extra benefit--if the vaccine is used in animals, it would trigger an different antibody to the wild-type virus, so it would be possible to tell the difference between the animals that have been vaccinated and those that have been infected naturally. Ikegami hopes that the efficacy will translate to larger animals, the next step in the research.

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