Some had thought that, because of this fact, the antibodies produced by the body would be almost identical after either infection, and that being infected with dengue may prepare the body somewhat for the arrival of Zika. Distressingly, this appears not to be valid.
Worse, it also appears that a prior infection of dengue actually strengthens the subsequent Zika virus infection by allowing the Zika to replicate far quicker – up to 12 times the speed it would otherwise.
This is because the immune system has been tricked. The dengue antibodies attempt to bind to the Zika virus, thinking it is still dengue. This triggers the release of white blood cells, who arrive to consume the Zika virus, assuming the antibodies have neutralized it. As they haven’t, the Zika virus then infects these incoming cells, and the infection spreads far quicker. This is a process known as antibody-dependent enhancement (ADE).
However, as an accompanying study in Nature shows, there may be hope. Two of these dengue antibodies actually manage to neutralize the Zika virus where all others fail. By examining tissue cultures infected first with dengue, then with Zika, a separate team of researchers observed that antibodies “anti-EDE1 mAb” and “anti-EDE2 mAb” successfully bind with the virus and allow white blood cells to destroy them.
Zika (illustrated here) and dengue, in a manner of speaking, are co-conspirators. Kateryna Kon/Shutterstock
“The difference between the EDE antibodies and the others is that the EDE antibodies target a very specific site on the virus,” Felix Rey, the head of structural virology at the Pasteur Institute and the study’s coordinating author, told IFLScience. “We now know that we need to develop a vaccine to stimulate production of antibodies against this particular site."
“Our antibodies could be considered to be used to treat pregnant women at risk of contracting Zika,” he concluded.
Ultimately, the information provided by these two studies could be used to help develop a vaccine that can neutralize both dengue and Zika in one fell swoop.