Utilization of modified in vitro assembled mason-Pfizer monkey virus particles

An alternative for utilization of genetically engineered viruses in gene therapies is the usage of pseudoviral particles made of viral structural proteins assembled into virus-like particles in vitro. The advantage of this system is a lack of particle infectivity and replication. Purified deletion mutant of Mason-Pfizer monkey virus (M-PMV) structural polyprotein Gag can be used for very efficient assembly of spherical virus-like particles in vitro. Appropriate viral structural proteins were purified in sufficient amounts and purity and the system of particle formation was optimized. We studied the incorporation of various therapeutically utilizable compounds into these particles. We found that different types of nucleic acids and other polyanions can be incorporated into formed particles. Various RNAs were incorporated with higher efficiency in comparison with plasmid DNA. On behalf of improving plasmid DNA incorporation we decided to modify viral structural protein. We have found that N-terminal modification of viral structural protein does not affect particle formation and that the modification is exposed on the particle surface. We selected short oligopeptides that should interact with prostate specific membrane antigen. By immunofluorescent microscopy we tested interactions of our particles with prostate cancer cells (LNCaP). Also Western blot method was used for determination of particle localization and cell entry. The entry of particles with incorporated pGFP DNA into LNCaP cells was also determined by fluorescent microscopy.