Virus-like particles as particulate vaccines.

Particulate structures hold great promise for the development of effective and affordable recombinant prophylactic as well as therapeutic vaccines. Different types of particulate structures, including virus-like particles (VLPs) and virosomes, have been developed depending on the nature of the viral pathogen to be targeted and the type of immune response (humoral vs cellular) to be elicited. Particulate structures allow the insertion or fusion of foreign antigenic sequences, resulting in chimeric particles delivering foreign antigens on their surface. Similarly, they are used as carriers for foreign antigens, including non-protein antigens, via chemical conjugation. Particulate structures, indeed, represent a very efficient system for delivering antigens to antigen presenting cells (APC) which, in turn, trigger and amplify the adaptive immune response. The present review will address the biological and immunological properties of particulate structures, in particular VLPs, as platform for vaccine development.