People who have been infected by Zika and other viruses could provide the answer to developing a vaccine, say researchers at The Rockefeller University. Their blood contains antibodies generated by the infections that may be used to create a vaccine.
In blood samples taken from subjects in Mexico and Brazil, the scientists found antibodies — proteins produced by the immune system — that block the virus from starting an infection.
These antibodies appeared to have been initially generated in response to an earlier infection by a similar virus that causes dengue. One such antibody, which they call Z004, was particularly effective at neutralizing Zika.
"These antibodies could be very useful in the near future," said researcher Davide F. Robbiani. "One could envision, for example, administering Z004 to safely prevent Zika among pregnant women or others at risk of contracting the disease."
While Zika, which is a mosquito-borne virus, usually causes mild symptoms in those who contract it, babies born to women infected during pregnancy face the risk of devastating neurodevelopmental abnormalities. Since there are no vaccines to prevent transmission of the virus or treatments to prevent birth defects, the only way to prevent it is to avoid mosquito bites.
For their study, researchers obtained blood samples from more than 400 people in Brazil and Mexico shortly after Zika began circulating.
Although they found a wide range of individual responses, they discovered that five of them which showed the best response to the virus contained the same species of nearly identical antibodies. Their similarity suggested these molecules were particularly good at fighting the virus.
When the researchers examined the antibodies' performance against Zika, one stood out: Z004, an antibody from a Mexican volunteer's blood.
When the Z004 antibody was given to mice vulnerable to Zika, it protected them from developing serious infections.
When the researchers looked at samples from the Brazilians which were collected six months before Zika arrived, they found that some had been previously infected by dengue 1. They theorized that was the reason why some people's immune systems coped better against Zika.
"It appears that, much like a vaccine, dengue 1 can prime the immune system to respond to Zika," said researcher Margaret R. MacDonald.
The study was published in the journal Cell.