The first human trials of an investigational vaccine against West Nile virus have begun. Researchers from the Oregon Health and Science University's Oregon National Primate Research Center will evaluate the efficacy of the vaccine in the clinical trials which are taking place at Duke University. Currently there is no approved vaccine for use in humans.

"West Nile virus represents a significant threat to public health in the United States, especially among the immunocompromised and the elderly," said Mark Slifka, Ph.D. "We believe our vaccine approach will not only be safe and effective for West Nile virus, but it could also provide significant protection against other important human pathogens, including yellow fever, dengue hemorrhagic fever, and, potentially even Ebola."

Slifka, who headed the study on the vaccine, is a senior scientist at the Oregon National Primate Research Center at OHSU; a professor of molecular microbiology and immunology in the OHSU School of Medicine; and the chief scientific officer and president of Najit Technologies, Inc. His OHSU team collaborated with experts on West Nile virus pathogenesis and immunology including Washington State University's Michael Diamond, M.D., Ph.D., and Slifka's Najit Technologies colleague, Ian Amanna, Ph.D.

Older methods of production for vaccines against the disease used formaldehyde-fixed 'dead' forms of the virus. However, this technique often causes serious damage to the virus' native surface structures. In contrast, the OHSU research team created the vaccine with a peroxide-based, proprietary platform called HydroVaxTM. The first vaccine production system platform to use hydrogen peroxide to render the virus inactive, this technique is unique and maintains these surface structures. This is crucial for the vaccine to function properly because these structures play a key immunogenic role as they trigger the immune system.

"The generation of a safe and effective inactivated vaccine against West Nile virus could minimize disease, long-term disability and even death in vulnerable individuals," said Diamond. "This vaccine showed great promise in pre-clinical models in animals. We are optimistic that it will stimulate protective immune responses that control infection and disease. This first trial in humans is an important milestone."

West Nile virus, spread by mosquitoes, is a potentially deadly human pathogen now found in Africa, Asia, Europe, and North America. As many as 3 million have been infected in the US since it was first reported in 1999. Of those about 40,000 led to illnesses that were then reported to the authorities, with more than 1,600 deaths. According to the Centers for Disease Control and Prevention (CDC), 47 states and the District of Columbia experienced West Nile virus infections in birds, mosquitoes, or humans in 2014.

Meanwhile, as the vaccine goes into human trials, researchers with the CDC and the National Center for Atmospheric Research (NCAR) have discovered a connection between the way that West Nile virus outbreaks happen in the US and the weather. They hope that their work will make predicting outbreaks easier. Obviously if outbreaks are better able to be predicted, the need for the vaccine can be better understood.

"We've shown that it may be possible to build a system to forecast the risk of West Nile virus disease several weeks or months in advance, before the disease begins to peak in summer," said lead author Micah Hahn, a scientist with both NCAR and CDC. "Having advance warning can help public health agencies plan and take additional steps to protect the public."

Find out more about the clinical trials of the investigational West Nile virus vaccine, funded by the National Institute of Allergy and Infectious Disease of the National Institutes of Health, at The report on the outbreak and weather patterns was funded by the National Science Foundation (NSF) and the CDC; it was published this week in the American Journal of Tropical Medicine and Hygiene.