Zika vaccine shows promise in early clinical tests

Dec. 5 (UPI) -- A vaccine against the Zika virus induced an immune response in a trio of early clinical trials, according to the National Institutes of Health.

The NIH announced on Monday that the vaccine was safe and garnered an immune response in participants of the phase 1 clinical trials conducted at Walter Reed Army Institute, Saint Louis University and Beth Israel Deaconess Medical Center.

The Zika purified inactivated virus vaccine features inactivated Zika virus particles. The viral particles can't replicate and cause an infection in humans, but because the protein shell of the particles remains whole, the immune system can recognize the virus.

"A vaccine is urgently needed to help prevent Zika infection, which can cause birth defects and other developmental abnormalities in babies born to infected women, as well as a constellation of other health problems in infected adults and children," Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, said in a news release. "We are encouraged by initial clinical trial results that indicate the ZPIV vaccine is safe and immunogenic, data that support additional clinical testing of the vaccine to determine its ability to prevent Zika virus infection."

The three studies included 67 adult participants, 55 of whom received the ZPIV vaccine, while 12 received a placebo. Neither participants nor investigators knew who received the vaccine and who received the placebo. Two intramuscular injections of the same dose were delivered four weeks apart. An adjuvant containing aluminum salts was also delivered to encourage a stronger immune response.

Blood samples revealed the presence of Zika virus antibodies in more than 90 percent of the participants who received the ZPIV vaccine within a month of the last dose.

To measure the effectiveness of the immune response, researchers extracted antibodies from the participants and injected them into mice. The mice were purposefully infected with Zika virus. Mice who received injections of antibodies were protected against the virus.

Scientists detailed ZPIV's initial clinical success this week in the journal The Lancet.

Follow up clinical trials will examine the ideal dosing size and schedule, as well as the possibility of prior immunity among participants.

Several other Zika vaccine candidates are also currently being tested by NSAID-sponsored researchers in the United States, Central and South America.