Use of parvovirus-like particles for vaccination and induction of multipleimmune responses

Expression of the VP2 gene of autonomous parvoviruses in insect cells with the use of the baculovirus system has led to the production of virus-like p articles (VLPs) formed by the self-assembly of VP2, These VLPs are expresse d at high levels and can easily be purified by salt fractionation, They are highly immunogenic in the corresponding host, being fully protective at do ses as low as 1-2 mu g of purified material per animal. No special adjuvant s are required. An interesting property of these particles is their usefuln ess as a diagnostic reagent for ELISA kits, which have successfully replace d conventional methods for parvovirus diagnostics based on haemagglutinatio n, Another application of the hybrid recombinant parvovirus-like particles of pig parvovirus (PPV) and canine parvovirus (CPV) is its use as an antige n delivery system. PPV:VLPs containing a CD8(+) epitope from the lymphocyti c choriomeningitis virus (LCMV) nucleoprotein are able to evoke a potent cy tolytic T-lymphocyte response and to protect mice against a lethal infectio n with LCMV, Also, PPV:VLPs containing the C3:T epitope from poliovirus eli cited a T helper response in mice. These T-cell epitopes were inserted into the N-terminus of the VP2 protein. Unfortunately, the N-terminus is not ad equate for antibody responses because it is inside the particle, Recent fin dings have shown that fine tailoring of the point of insertion around the t ip of loop 2 of the surface of CPV allowed the elicitation of a potent anti body response, Thus mice immunized with chimaeric C3:B CPV:VLPs were able t o elicit a strong neutralizing antibody response (> 3 log(10) units) agains t poliovirus, We now have the possibility of using these particles to elici t different immune responses against single or multiple pathogens in a simp le and economic way.