Spotlight on: Developing a Zika vaccine

Posted on: 28 April 2023 by Dr Krishanthi Subramaniam in April 2023 posts

For World Immunisation Week, Dr Krishanthi Subramaniam, a Tenure Track Fellow based in the Institute of Infection, Veterinary and Ecological Sciences, tells us about her work to help develop a novel Zika vaccine.

Globally, mosquito-borne viruses account for nearly 400 million infections and up to 700,000 deaths per annum. These figures are likely to increase as temperatures across the world continue to rise, expanding the areas in which mosquitoes can thrive.

Zika virus is one such mosquito-borne virus, responsible for the 2016 epidemic that devastated countries across Latin America such as Brazil. Zika virus belongs to the family Flaviviridae and can cause a mild, self-limiting illness in the majority of infected individuals. However, Zika infections can also result in congenital malformations in developing fetuses such as microcephaly and is associated with several neurological disorders including Guillain-Barré syndrome, transverse myelitis, and meningoencephalitis. Furthermore, the persistence of the virus in semen and the female genital tract months after infection further exacerbates the problem.

At present, there are still no licensed vaccines for Zika and none that is safe to use during pregnancy.

I’m part of a University of Liverpool-led team that has been working over the past six years to develop a new Zika vaccine. The Liverpool vaccine includes specific Zika antigens incorporated into a viral vector with an excellent safety profile. Our vaccine is also expected to be safe for use in pregnant women.

The majority of my work has focused on demonstrating the effectiveness and immunogenicity of the vaccine using animal models. Pre-clinical assessment of the vaccine showed protection in animals challenged with two different Zika strains, MR-766 and PRVABC59 and the results of my work will be submitted for peer review following patent registration.

Excitingly, we have just reached a huge milestone in the project by beginning first trial of our new vaccine in humans at the Clinical Research Facility within the Royal Liverpool University Hospital. Healthy volunteers recruited to the trial will receive two doses of the new vaccine to evaluate its safety, tolerability and its ability to produce an immune response. The vaccine will be assessed in groups of four volunteers at a time, with numbers increasing as evidence of safety accumulates. Up to 40 volunteers in this phase of work is planned which will be taking place over the next nine months.

If successful, the next step is to establish collaborations with health and industry stakeholders to test our vaccine in a Phase II trial. Our team is currently engaging with different health ministries in Latin America who have demonstrated interest in testing our vaccine.

Zika should not be forgotten especially since climate change is contributing to the spread of the Aedes mosquitoes into regions where immunity is either low or absent. Vaccines like ours will enable us to be better prepared for the next Zika outbreak. The pandemic taught and continues to teach us that infectious diseases is a global issue but with the help of vaccines we can make great strides in keeping everyone safe.

World Immunisation Week is celebrated in the last week of April each year and aims to highlight the collective action needed and to promote the use of vaccines to protect people of all ages against disease.