PilVax – A novel peptide delivery platform for mucosal vaccination based on the pilus structure of Group A Streptococcus

 Our main research interest is an important bacterial pathogen to humans, the Group A streptococcus (GAS). This bacterium causes a wide range of diseases ranging from superficial skin and throat infections, to invasive diseases and serious immune complications. Our research focused on the GAS pilus, which is a surface structure involved in host cell adhesion. In this regard, we are currently developing a novel vaccine strategy based on the GAS pilus termed PilVax.
PilVax is a novel peptide delivery platform that utilises the GAS pilus structure to carry a stabilised and highly amplified peptide on the surface of the food-grade bacterium Lactococcus lactis. A proof-of-concept study showed that several loop regions in the structure of pilus backbone protein Spy0128 could be utilised as the peptide insertion site. Recombinant L. lactis strains expressing the modified pili on the surface were used to immunise mice intranasally, and elicited substantial systemic and mucosal antibody responses. PilVax overcomes the common shortfalls of synthetic peptide vaccines in poor immunogenicity and instability, and takes advantage of the safety profile and natural adjuvancy of the lactococcal vehicle. PilVax can be a versatile peptide delivery platform for multiple antigens, and can be built on antigenically-different pilus types to facilitate subsequent immunisation. Current works on this project include developing PilVax into effective mucosal vaccines against various diseases, and investigating of the immunological characteristics of GAS pilus. In this presentation, we will describe a pilot project in collaboration with Dr. Fujihahi at the Institute of Medical Science, The University of Tokyo, and Dr. Asanuma at the National Institute of Infectious Diseases on an universal flu vaccine based on the PilVax system.