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.
Keywords: Norovirus; P particle; histo-blood group antigens..