Protecting against three diseases at once may seem improbable, but a recent study has produced a vaccine which may do just that.

In a joint collaborative effort involving Tulane National Primate Research Center (TNPRC), the National Institutes of Health and the U.S. Army, researchers have developed the first vaccine that provides complete protection against three types of equine encephalitic viruses in nonhuman primates.

There are no existing vaccines or treatments against Western, Eastern and Venezuelan equine encephalitis, all of which are spread by mosquitoes. During summer months when mosquitos increase, horse populations are particularly susceptible to fatal infection. Transmission from horses to humans can occur via mosquitoes and can cause serious illness and death in vulnerable populations like the elderly and children.

Using nonhuman primate and mouse models of aerosol infection, the study showed that the trivalent virus-like particle (VLP) vaccine induced an immune response and provided complete protection from all three viruses. The response was strong enough to effectively block the neurological effects of infection, which is normally present with any of the three viruses.

Chad Roy, PhD, director of Infectious Disease Aerobiology and Biodefense Research Programs at Tulane, said one reason this finding is significant is because of its possible influence on the field of bioweaponry. These encephalitic viruses are possible bioterrorism agents because of their potential to be aerosolized, underlining the need for a vaccine in the event of an attack.

“These findings are an important milestone in the development of a vaccine that could be employed in the event that these viruses are ever used in a deliberate release,” noted Roy.

Of course, the vaccine could also be used to prevent or slow the natural spread of equine encephalitic viruses.

“This is a significant step, not only in protecting human populations from possible threats of bioterrorism, but also protecting both animals and humans from natural vector-borne disease transmission,” said Vicki Traina-Dorge, PhD, associate professor of microbiology and immunology at Tulane.

As the global climate warms and human and animal populations increase, mosquito-borne infectious diseases have greater potential to spread. These vaccines could be highly useful in protecting global populations from both natural and man-made outbreaks.