Virus-like particles for vaccine development

Virus-like particles (VLPs) resemble viruses in their organisation and structure but are non-infectious as they do not contain viral genetic material. The importance of these particles as tools has been realised in vaccine development with quite a few commercially available prophylactic vaccines now utilising this technology.

The EU-funded 'Virus-like particles: The next step in gene therapy' (VLPSIRNA) project investigated the use of VLPs for delivering carbohydrate antigens as immunogens. Carbohydrates — also known as glycans — are present on the surface of a variety of pathogens and malignant cells in a highly repetitive manner. Their utilisation as vaccine candidates is hampered by their poor immunogenicity and the low-affinity of anti-carbohydrate antibodies.

To overcome this, VLPSIRNA researchers proposed to increase the immunogenicity of glycans by delivering them through the inherently immunogenic VLPs. Given the potential to chemically and genetically manipulate the surface of VLPs, they provide a unique and robust platform for optimising antigen delivery.

The platform of bacteriophage Q beta was exploited for the generation of an effective vaccine against the pathogen Streptococcus pneumoniae (pneumococcus). More specifically, the surface of the virus was functionalised with sugar serotypes of pneumococcus and their immunogenicity was evaluated in mice. The generated immune response was significantly higher than any other method tested previously, indicating the efficacy of VLPs as polysaccharide vaccines.

Using tumour-associated antigens such as Tn antigen, the VLP approach was extended to the design of anti-cancer vaccines. Scientists attached this antigen to the cowpea mosaic virus (CPMV), a plant virus, and tested the immunogenicity of these vaccine formulations in mice.

Collectively, VLPSIRNA findings support the use of VLPs as immunogen carriers in vaccine formulations, mainly for reinforcing the effectiveness of poorly immunogenic antigens including polysaccharides. The potential of the generated platform for the development of anti-cancer vaccines is expected to find immediate clinical applications such as cancer and disease prevention.

related link: http://cordis.europa.eu/result/brief/rcn/12433_en.html