Scientists Discover Potentially Safer Zika Vaccine

Researchers identified a vaccine that could defend against Zika virus without producing antibodies.

A strong global initiative to battle Zika has produced more than 30 vaccine candidates since outbreaks in 2015-2016 in Brazil.

(Photo: iStockphoto)

In a breakthrough development, researchers at University of Nebraska-Lincoln might have identified a vaccine that could defend against Zika virus without producing antibodies.

In a press release, researcher Eric Weaver and his team of doctoral students Brianna Bullard and Brigette Corder, expressed hope that future experiments will yield significant findings that could have a profound impact on the field of vaccinology.

In Weaver’s words,

If we can figure out the mechanism, we might be able to apply it to other vaccine strategies. This would be a huge leap for immunology and vaccine research.

The challenge in developing zika viruses, among others, is that antibodies against Zika virus can worsen Dengue virus infection. Also called the ‘anti-body enhancement’ (ADE) phenomenon of disease, this has become a major obstacle in the development of safe Dengue and Zika vaccines.

The research has been published online in the journal Scientific Reports.

The scientists used two forms of weakened Adenovirus to serve as vectors to deliver the Zika vaccine. In the press release, they explained,

Adenoviruses, which typically cause mild illness such as the common cold, are modified so that they are replication-defective and incapable of causing disease. The modified viruses are regarded as safe and highly effective vaccine vectors capable of inducing long-lasting protective immune responses against infectious pathogens.

The researchers inserted structured genes of Zika into key areas of the Adenorvirus Type 4 and Adenovirus Type 5 genomes. Tested in mice, both vaccines offered strong T-cell responses and substantial protection against Zika infection.

However the vaccine based on Type 4 Adenovirus induced strong T-cell responses with undetectable antibodies. T-cells are a type of white blood cells that are at the core of the system that tailors the body’s adaptive immune response to specific pathogens.

To our knowledge, this is the first report of a vaccine that uses the prM-E genes of Zika virus to induce protective immunity without inducing anti-Zika virus antibodies. The lack of antibodies may very well circumvent the potential risks of ADE, resulting in an effective and safer vaccine than those currently in clinical trials.

Eric Weaver