Immunogenicity of poliovirus B and T cell epitopes presented by hybrid porcine parvovirus particles

Abstract

We have analysed the potential capacity of hybrid porcine parvovirus (PPV) capsids to present foreign epitopes to the immune system. Foreign sequences were introduced into the N and C termini of PPV VP2, which was previously shown to assemble spontaneously into parvovirus-like particles. The integrity of the C terminus was shown to be essential for preserving the structure of the capsid and therefore could not be used for epitope fusion. In contrast, insertion of sequences corresponding to T and B cell poliovirus epitopes in the N terminus did not alter the formation of particles. Moreover, the chimeric capsids containing the C3 : T epitope were able to induce a T cell response in vivo. However, hybrid particles containing the C3 :B epitope fused to the N terminus did not induce any peptide-specific antibody response, suggesting that the inserted B cell epitope was not exposed at the surface of the particles. These results show that the N terminus in PPV empty capsids is not an adequate site for insertion of B cell epitopes, but may be useful for T cell epitope presentation and suggest that the N terminus is located in an internal position.

In Vivo, Dendritic Cells Can Cross-Present Virus-Like Particles Using an Endosome-to-Cytosol Pathway

“…Very recently, the existence of cross-presentation and crosspriming as general, physiological processes to induce CD8 ϩ T cell response has been doubted (76) on the basis of the lack of convincing in vivo solid experimental evidence. Previous studies have clearly showed that exogenous PPV-VLPs can induce a protective antiviral response, based on the induction of a high frequency of CTLs of high affinity (12,13,16,77). The evidence presented in this report clearly establishes that PPV-VLPs processing by DCs involves cross-presentation.…”

“…We have developed an Ag delivery system based on nonreplicative, recombinant parvovirus-virus-like particles (PPV-VLPs) formed by the self-assembly of the VP2 capsid protein of porcine parvovirus (PPV) (12,13). The VP2 protein (14), carrying foreign CD8 ϩ T cell epitopes, self-assembles into 25-nm VLPs after expression in insect cells (13).…”

Serodiagnosis of Mice Minute Virus and Mouse Parvovirus Infections in Mice by Enzyme-Linked Immunosorbent Assay with Baculovirus-Expressed Recombinant VP2 Proteins

“…These vectors were used to express the recombinant capsid proteins MMV rVP2 and MPV rVP2 in insect cells. It is known that many parvovirus recombinant VP2 proteins, including MMV rVP2, assemble into virus-like particles (VLPs) when expressed in baculovirus expression systems (6,8,16,24,27). To determine if baculovirus-expressed MMV rVP2 or MPV rVP2 proteins self-assembled into VLPs, we subjected clarified supernatants of insect cells infected with the MMV-rVP2 Bac vector or the MPV-rVP2 Bac vector to CsCl gradient ultracentrifugation.…”

Influence of flanking sequences on presentation efficiency of a CD8+ cytotoxic T-cell epitope delivered by parvovirus-like particles

“…Our data illustrate that the sequence Trp-Thr-Ser is detrimental for PPV VP2 expression and for capsid formation. A similar effect, although less evident, was previously observed for the insertion of two CD4 + T-cell epitopes, polio C3:T (Sedlik et al, 1995) and PreST from hepatitis B (Lo-Man et al, 1998), which also contain a Trp residue. In these cases, the particles with an altered morphology assembled with low efficiency.…”

“…Several constructs of the OVA epitope with different flanking sequences or different lengths were prepared (Table 1). Plasmid pPPV29mod (Sedlik et al, 1995), which contains a unique XhoI restriction site immediately downstream of the initiation codon of the VP2 gene, was the starting material for the cloning experiments. The plasmid was linearized with XhoI (MBI Fermentas) and treated with alkaline phosphatase (Roche Molecular Biochemicals).…”