NIH-developed dengue vaccine candidate shows promise

A candidate vaccine developed by National Institutes of Health scientists against dengue, a tropical disease that is classified as a biological weapon, recently demonstrated a strong immune response in an early stage clinical trial.

The trial, which was sponsored by the NIH's National Institute of Allergy and Infectious Disease, tested a single dose of four versions of the investigational dengue vaccine TetraVax-DV. The four versions of TetraVax-DV correspond to the four related dengue fever viruses that are transmitted to humans by Aedes mosquitoes.

The World Health Organization estimates that 50 million to 100 million cases of dengue fever occur worldwide each year, resulting in 500,000 severe cases that require hospitalization.

"The global burden of dengue is enormous - and it is growing," NIAID Director Anthony S. Fauci said. "We are cautiously optimistic about these recent clinical trial results with this candidate tetravalent vaccine developed at NIAID; however, much more work still needs to be done."

The researchers determined that all four candidate vaccine combinations induced antibody responses against each dengue virus. TV003 appeared to induced the most balanced antibody response against the dengue viruses. An immune response to at least three viruses was seen in 90 percent of the vaccinees receiving TV003.

"What is promising about TV003 is that it elicited solid antibody responses after just one dose," Stephen Whitehead, the development leader of the vaccine candidates, said. "Other vaccines in development require two or three injections at higher doses to achieve similar results."

All four vaccine candidates were found to be safe and the most common side effect was a faint rash.

The researchers plan to begin Phase II trials soon in Thailand and Brazil to evaluate the safety of TV003 and its capacity to generate an immune response. If the vaccine continues to show promise, it could increase the preparedness of the U.S. in case dengue is used as part of a biological attack.

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