La Jolla Institute finds new way to look at dengue vaccines

Scientists at La Jolla Institute for Allergy and Immunology may have found evidence that previous approaches to designing an effective dengue vaccine were incorrect.

Scientist and Doctor of Biological Science Alessandro Sette from La Jolla Institute lead the research on dengue vaccine and found T cells, which are the cells of the immune system which fight off disease, play a significant role in controlling a dengue viral infection, as opposed to the previous belief of using aberrant responses.

"The current thinking in the field is that the goal of a dengue vaccine should be the induction of antibodies and not T cells," Sette said. "But our results suggest that both cell types are needed to produce a strong immune response against dengue infection."

The study was conducted by examining blood samples from Sri Lankan adults that were naturally infected by dengue viruses. It was found in Sette's trials that T cell immunity contributed to protecting the infected person, rather than leading to vascular permeability, which only occurs in extreme cases.

The most severe cases of dengue are the result of an individual being infected by more than one of the four strands of the dengue virus. The virus currently infects between 50 and 100 million people annually and causes dengue fever, dengue hemmorhagic fever, dengue shock syndrome and death.

The new findings by Sette's team suggest the new vaccine will help protect against multiple strands, keeping the severity of the virus in patients under control. Further research is required, however, in order to produce a stronger, more effective vaccine based on this theory; the current vaccine is only 30 percent effective.

"We showed that CD8 positive T cells play a very important role in controlling dengue infection in mouse models," Sujan Shresta, a scientist at La Jolla, said. "I am not saying that antibodies are not important, but rather that T cells are also needed to induce strong protection against dengue."

This research, along with another study of which Shresta has been a part, has been called controversial, as it not only contradicts previous findings and methods of approaching dengue vaccine development, but it also suggests previous methods of using antibodies can progress the dengue virus in an infected person. The study also found that every person responds differently to dengue due to their genetic make-up