People who become infected with the dengue virus are at increased risk of experiencing a more severe infection later in life, and researchers are beginning to understand why. Such knowledge may play an important role in helping those trying to develop a vaccine against the virus.
The mosquito-borne virus causes up to 100 million infections a year. The World Health Organization reports that dengue disease is now endemic in more than 100 countries, and recent estimates suggest 3 billion people, almost half the world’s population, are at risk.
The virus that causes dengue disease is divided into 4 closely related serotypes that can be further divided into genetic variants. A person’s prior immune response to one serotype of the dengue virus can influence interactions with another virus serotypes in a subsequent infection, and how that interaction occurs could mean the difference between getting a mild fever or experiencing a fatal circulatory failure from dengue hemorrhagic fever or dengue shock syndrome.
In an article appearing today in Science Translational Medicine, researchers, examined data from 2 independent Nicaragua-based studies:, a hospital-based study that examined children admitted with dengue between 2005 and 2009, and a prospective study begun in 2004 that followed 3800 children who initially presented with dengue-like illness and subsequently gave blood samples to identify silent virus transmission and to determine dengue immune status. By tracking cases of dengue infection in both studies, the researchers were able to identify a large increase in severe dengue disease and then sequenced the virus over time. They found genetic changes in the virus that coincided with changes in disease severity, but only in the setting of previous immune response to specific dengue virus serotypes.
A member of the research team, Eva Harris, PhD, professor of infectious diseases and vaccinology and director of the University of California Berkeley’s Center for Global Public Health, said in a release, “Our findings have implications for vaccine development and implementation, as the precise genetics of vaccine strains, as well as the timing and serotype sequence of infection prior to and after vaccination, play an important role in determining the outcome of infection.”