PODS (POlyhedra Delivery System) exploits the unique properties of polyhedrin, a protein made by a cypovirus that infects silkworms. The polyhedrin protein forms small crystal cubes within infected insect cells. These crystals incorporate newly made copies of the virus into their crystal structure, protecting them following release from the insect, resulting in a distinct survival advantage. Genetic engineering techniques have now been used to adapt this viral survival mechanism to encapsulate essentially any protein, including vaccine proteins. As well as eliminating the need for cold storage, PODS crystals are resistant to acid and have the potential to provide vaccines that can be taken orally.
Prof Hajime Mori, Kyoto Institute of Technology, and Prof Ian Goodfellow, Cambridge University
Norovirus, also known as the winter vomiting causes significant health issues around the world. The Centre for Disease control (CDC) states "Worldwide, about one out of every five cases of acute gastroenteritis (diarrhea and vomiting illness) is caused by norovirus. Globally, norovirus is estimated to be the most common cause of acute gastroenteritis. It is responsible for 685 million cases every year, 200 million of these cases are among children younger than 5 years old. This leads to an estimated 50,000 child deaths every year, nearly all of which occur in developing countries".
Our collaborators in Cambridge and Kyoto are developing a virus-like protein (VLP) to act as a temperature-stable vaccine. The protein self-assembles before being incorporated into the PODS crystal.
Norovirus-like particles captured in a PODS crystal.