USP: Zika vaccine research advances in tests with mice

The production of a vaccine against the Zika virus has advanced another step: researchers from the Institute of Tropical Medicine (IMT), at the University of São Paulo School of Medicine, have completed laboratory tests on mice, and the results were considered satisfactory, with a safe and effective vaccine.

The tests were performed on genetically modified mice—more susceptible to the Zika virus—and showed that the vaccine induced the production of antibodies that neutralized the virus. The vaccine also prevented the infection from developing, leading to symptoms and lesions.

The researchers also investigated the effects of Zika virus infection on various mouse organs, such as the kidneys, liver, ovaries, brain and testicles, with success mainly in the latter two.

The vaccine uses a "virus-like particle" (VLP) platform, a preferred alternative to other vaccines, such as those for Hepatitis B and HPV. With this production method, the formulation dispenses with substances that enhance the immune response, known as adjuvants.

Biotechnology

The team also adopted a biotechnology production strategy, using prokaryotic systems, in this case bacteria, which allow for high production, although they require attention to bacterial antitoxins.

The strategy had already been used by the group in the production of a vaccine against Covid-19.

Gustavo Cabral de Miranda, the physician leading the research group, was in Oxford between 2014 and 2017 and participated in the development platform run by the Jenner Institute. This group developed the basis for the technology adapted with AstraZeneca, one of the first Western vaccines used in the 2020 pandemic.

"There, we studied ChAdOx1 (a chimpanzee adenovirus modified in the laboratory) for applications in malaria, Zika , chikungunya , among others. And this generated so much knowledge of the technology's capabilities that, when the pandemic emerged, significant funding emerged, and the technology advanced very quickly toward practical applications," Miranda told Agência Brasil.

He explains that the technology is usually divided into two components: the carrier particle (VLP), which "catches the attention" of the immune system and is recognized by it as a virus, and the viral antigen, which stimulates the immune system to produce specific antibodies, which in turn prevent the pathogen from entering the cells.

The structure used was the EDIII antigen, a part of the Zika virus envelope protein whose function is to bind to a receptor on human cells.

Human testing

The group is seeking funding for the next phases of research involving human populations. Since this involves millions of reais, it's a lengthy process.

Meanwhile, they are testing other solutions, such as messenger RNA vaccines, as well as different heterologous and homologous immunization strategies. The research, to date, has been funded by the state research agency, FAPESP.

"Any vaccine production is not a simple process. To set up a plant, as we say in science, a vaccine production factory, there will always be a need for change. Today, the most common approach is traditional vaccine factories. So, naturally, research with traditional vaccines has the greatest chance of progress," explains Miranda.

The researcher further explains that technology is advancing. According to Miranda, factories capable of working with other vaccine platforms open up a huge range of possibilities in terms of technology and rapid response capabilities, as was the case with the Covid-19 pandemic.

"I mentioned the adenovirus vaccine; in short, that's our main objective. What I'm developing is part of the technological process so we can produce our vaccines here in Brazil. Whether it's now or ten years from now, we need to have this continuity, whether in the short, medium, or long term."