Virus-like particles (VLPs) are multiprotein structures that mimic the organization and conformation of authentic native viruses but lack the viral genome, thus making them safe and effective vaccine candidates. VLPs can present conformational epitopes similar to the native virus in a highly repetitive fashion; hence, humoral and cellular immune responses are expected to be significantly improved compared to other types of vaccines (e.g., subunit or recombinant protein immunogens). The potency of these particles can be significantly enhanced if specific native viral proteins that have an immunosuppressive function are excluded from the VLPs composition. Attenuation or inactivation is not required; this is particularly important as epitopes are commonly modified by inactivation treatments. Clearly, not all viruses are appropriate vaccine targets; some VLPs have also been generated as a means of understanding the assembly or architecture of viruses. To date, VLPs have been produced for more than 30 different viruses that infect humans and other animals. A handful of VLP-based vaccines have been approved and are currently commercialized worldwide (e.g., Engerix ® against hepatitis B and Cervarix® against human papillomavirus) and several ones are under preclinical and clinical evaluation against recurrent and emerging diseases (e.g., Influenza, parvovirus, Norwalk).
Author: Marco Silvano (ESR7)