VLP-vaccines

VLP is the acronym for "virus-like particles" also known as virus-like vesicles (VLVs). VLP vaccines belong to the group of dead vaccines, i.e. they contain only "dead", non-replicable material. VLP vaccines contain virus-like particles. These are virus particles, but they do not contain nucleic acids. The genetic material of the virus is missing. Thus, the particles cannot replicate in the target cells. They are also not capable of delivering a transgene.VLP is the acronym for "virus-like particles" also known as virus-like vesicles (VLVs). VLP vaccines are among the dead vaccines, meaning that they contain only "dead" material that is not capable of replication. VLP vaccines contain virus-like particles. These are virus particles, but they do not contain nucleic acids. The genetic material of the virus is missing. Thus, the particles cannot replicate in the target cells. They are also not capable of delivering a transgene.

The virus particles are usually a modified capsid of the virus. Capsids are regular structures of proteins that serve to package the viral genome. Such capsids can, for example, be fused with a so-called TLM peptide (translocation motif), enabling it to pass through cell membranes and spread throughout the body. Further modifications can be made to this "platform" to incorporate loading sites for the antigen against which the immune protection is to be established. The membrane permeability of the vaccine candidate also allows needle-free application of the vaccine in the form of an oral or transdermal (patch) application.

The antigens are usually incorporated into small protein envelopes or lipid vesicles grown in plant or insect cells. The modular combination of antigen and adjuvant in VLPs enhances the effect of the antigen. The immune system views these VLPs as real viruses. This triggers a normal antiviral immune response.

VLPs already form the basis of the vaccines against human papilloma viruses approved in Europe. VLPs based on the Norwalk virus, the parvovirus and filoviruses are also used.

Infections with newly emerging pathogens, such as Ebola, Zika or Coronavirus, are rapidly assuming epidemic proportions. In order to make a vaccine available for these pathogens in a timely manner, work is being done on so-called vaccine platforms based on VLP technology. This is based on a carrier that already contains antigens of other pathogens and thus basically ensures an immune response. If necessary, the vaccine of such a platform is additionally loaded with the antigens of the new pathogen and can enter clinical testing in a timely manner. Vaccine platforms are currently seen as an important tool to shorten the response time to emerging pathogens by providing a specific vaccine.

1. Alexopoulou A et al (2020) New Approaches to the Treatment of Chronic Hepatitis B. J Clin Med 9:3187.
2. Reynolds TD et al (20ß15) Virus-Like Vesicle-Based Therapeutic Vaccine Vectors for Chronic Hepatitis B Virus Infection. J Virol 89:10407-1015.
3. Zahn T et al (2020) A new approach for therapeutic vaccination against chronic HBV infections. Vaccine 38:3105-3120.