Virus-like particles , viral vaccine

Viral structural proteins expressed by baculovirus infected insect cells assemble into multimeric structures that resemble viral core-like particles and virus-like particles (CLPs and VLPs, respectively). This presentation has brought the attention of researchers for the potential use of these structures as safe immunological reagents for virus or antibody detection in enzyme immuno assays, as vaccines, and more recently, as gene delivering systems for gene therapy [9]. 

Ramqvist T, Andreasson K, Dalianis T. 2007. Vaccination, immune and gene therapy based on virus-like particles against viral infection and cancer. Exp Opin Biol Ther 7 997-1007. 

Virus-like particles (VLPs) are self-assembling particles ranging in size in the range 20-100 nm they are composed of one or several viral proteins expressed in vitro through recombinant technologies. A VLP-based vaccine for Hepatitis B is currently on the market,as well as a prophylactic human papillomavirus (HPV) virus-like particle vaccine, which has shown clinical efficacy when administered intramuscularly. ... 

Purity requirements depend on the intended use of the biopharmaceutical, dose and risk-benefit ratio. The selection of purification method should consider physicochemical characteristics of the particle to be isolated. For viral particles it is relevant to consider the influence of isoelectric point (pi), surface hydrophobicity, the presence or absence of an envelope, hydrodynamic diameter and lability of virus particles. Viruses should not have their level of infectivity reduced after a purification stage when they are used as vectors, and tests should be carried out to check this. ° During the process of vaccine manufacturing, the production of virus-like particles is dependent on physicochemical parameters such as pH, ionic strength and medium temperature. Type and concentration of chelating agents also seem to affect the protein macrostructure stability and thus should be observed. ... 

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