Production, characterization and immunogenicity of P particles derived from norovirus GII.4 genotype 2004 variant.

Norovirus (NoV) is the main cause of nonbacterial infectious gastroenteritis. Due to the difficulty of culturing the virus, research on vaccine against NoV is focused on virus-like particles (VLPs). On the other hand, the P particles assembled from the P domains of NoV capsid protein become a promising vaccine candidate. GII.4 is the most prevalent genotype of NoV. While the immunogenicity of P particles derived from the GII.4 1996 variant has been investigated, the research on P particles of more recently prevalent variants is lacking. In this study, the P domain of the capsid protein of GII.4 genotype 2004 variant was expressed in Escherichia coli, purified and auto-assembled into P particles of 14-25 nm. Immunization with P particles induced specific serum antibodies with titers of 245,600 and 145,700 in mice and rabbits, respectively. The GII.4 NoV 2004 variant bound to type A, B and O secretor-positive saliva and immune sera blocked this binding, suggesting induction of neutralizing activity in such sera. Thus, this study demonstrated the immunogenicity of NoV P particles generated from E. coli and provided evidence supporting the development of this approach.