Recombinant viral-like particles of parvovirus B19 as antigen carriers of anthrax protective antigen.

Viral-like particles (VLPs) of parvovirus B19 were employed as an antigen carrier to present antigenic determinants of Bacillus anthracis. The small-loop peptide and the full-length domain 4 of protective antigen (PA) were chosen as immunogens for presentation on the VLP-capsid surface and subsequent immunization of BALB/c mice. The recombinant VLPs induced anti-PA IgG titers of up to 2.5 x 10(4). Neutralization assays showed that the recombinant VLPs elicited neutralizing anti-PA antibody titers of up to 1:400 and showed potential for the prevention of lethal toxin-induced mortality of mouse-macrophage cells (RAW264.7). In postimmune sera, no anti-PA titers were detected against synthetic small-loop peptide. Recombinant VLPs demonstrated the capacity to retain the immunogenicity of the displayed microbial PA-epitopes and elicited robust levels of anti-PA antibody titers. These findings suggest that the recombinant VLPs of parvovirus B19 have potential as an additional tool in the development of sub-unit vaccines.