Study: Dengue virus research needs to focus on people, not mice

Dengue virus infection is spread by mosquitoes, and in healthy people, just leads to a flu-like illness. However, it can be more serious and is a major burden in more than 50 countries worldwide. There are no dengue virus vaccines so far, and new research from the University of North Carolina at Chapel Hill and Vanderbilt University could help speed vaccines to the market.

One of the issues with dengue virus vaccine development is that there are four strains of the virus, and people who are immune to one strain after an infection are actually more likely to get dengue hemorrhagic fever and dengue shock syndrome if they become infected with another strain. These illnesses can be fatal, and so vaccine developers need to avoid any immune response that might enhance disease.

In the study, published in Proceedings of the National Academy of Sciences, the researchers looked at blood from 7 people who had been infected with the dengue virus, and found that they produced a large number of antibodies that are not very effective, and a small number of highly potent antibodies. The research also found that humans produced antibodies against structures on the surface of the whole virus, whereas mice had an immune response to small fragments of the virus, suggesting that research in mice might not apply as closely to humans as once thought.

"In the past, researchers have relied on mouse studies to understand how the immune system kills dengue virus and assumed that the mouse studies would apply to people as well," said senior study author Aravinda M. de Silva, Ph.D., associate professor of microbiology and immunology at the UNC School of Medicine.

Dengue virus infections are spreading globally, and the most advanced dengue vaccine, in Phase III clinical trials with Sanofi Pasteur, isn't expected to be approved until 2014. According to de Silva, these developments may mean that researchers will have to look again at vaccines in development to see if they are targeting fragments or the whole virus--this could predict whether they will actually be effective in humans.

- read the press release
- see the abstract