Zika is caused by a virus transmitted mainly by infected female Aedes aegypti mosquitoes, but it can also spread through sexual contact. Most infected people experience mild symptoms for two to seven days, including fever, rash, conjunctivitis, muscle and joint pain, or headache.

Zika can also cause severe congenital neurodevelopmental disorders. The most notable is microcephaly—when a baby is born with a much smaller‑than‑expected head. The virus can also trigger neurological problems in infected individuals, including Guillain‑Barré syndrome.

Search for a vaccine

To date, no vaccines or treatments have been approved for Zika. Other strategies have not produced clearly effective results.

But there is good news. UCLA researchers have developed a Zika vaccine technology that is highly effective and safe in preclinical mouse models. In pregnant mice, the partially CIRM‑funded study showed the vaccine prevented systemic infection in both the mothers and their developing fetuses.

In engineering the vaccine, researchers deleted the portion of the Zika genome that codes for the viral shell. The viral shell is the structure the virus uses to evade the immune system.

“This modification stimulates an immune response and prevents the virus from replicating,” said Vaithilingaraja Arumugaswami, D.V.M., Ph.D., Associate Professor at UCLA.

This work is timely. Major Zika outbreaks occur roughly every seven years. Because the last large outbreak was in 2016, “it is only a matter of time before we see the virus spread again,” said co‑senior author Kouki Morizono, M.D., Ph.D., of UCLA.

“The COVID‑19 pandemic showed the power of preparedness and clear communication,” Arumugaswami said. “Our research is an important first step toward a vaccination program that could curb Zika and prevent large‑scale outbreaks.”

This research is published in Microbiology Spectrum,  a journal of the American Society for Microbiology.