While the Zika virus is primarily transmitted by mosquitoes, research has shown that the disease can affect semen and sperm and can therefore be spread through sexual intercourse.

Now, a new study conducted by scientists from The Wistar Institute and colleagues has shown that a novel DNA-based vaccine protects the testes and sperm from Zika-associated damage in animal models, further demonstrating the protective benefits of this new approach in fighting the spread of the virus.

The vaccine that was used in this study was developed collaboratively between Wistar, Inovio Pharmaceuticals, Inc., and GeneOne Life Science Inc., and is currently in clinical trials around North America. Research at Wistar is being led by David B. Weiner, Ph.D., Executive Vice President of The Wistar Institute, Director of The Wistar Institute Vaccine & Immune Therapy Center and the W.W. Smith Charitable Trust Professor in Cancer Research.

In this latest study, led by researchers at the Public Health Agency of Canada and Laval University with additional support provided by Weiner and his lab, the team showed how a synthetic DNA vaccine that expressed specific antigens for Zika offered complete protection to mice against Zika-induced damage to the testes and sperm. The researchers note that this is an important finding because the Zika virus can linger in the sperm of humans infected with the Zika virus for several months after the initial onset of symptoms. This study suggests this vaccine might provide the additional benefit of lowering the risk of sexual transmission of Zika and being able to protect this important viral reservoir.

Last year, a phase 1 trial of this vaccine opened in North America and was reported to be safe and immunogenic, producing immunity in 100 percent of vaccine recipients. A second phase of testing this vaccine is currently underway in Puerto Rico. Together, these studies will help to provide important information regarding the effectiveness of this vaccine in the clinic.

A total of nearly 4,000 cases of Zika infection have been reported in the United States, according to the U.S. Centers for Disease Control, and more than 100 cases of Zika infection originating within the United States have been reported. Data supports approximately 10 percent of Zika virus-infected pregnancies can lead to visible birth defects from Zika infection.