Production and characterization of virus-like particles and the P domain protein of GII.4 norovirus.

Noroviruses are an important cause of epidemic acute gastroenteritis in humans. In this study the production and characterization of GII.4 norovirus virus-like particles (VLPs) in insect cells is reported. Furthermore, the expression of corresponding norovirus polyhistidine-tagged P domain protein in Escherichia coli is described. The protruding P domain of the norovirus capsid is known to contain determinants for antibody and receptor binding. Therefore, P domain proteins were studied as an alternative diagnostic tool for evaluating norovirus infection. Analyses by dynamic light scattering and cryo-electron microscopy revealed the presence of intact VLPs with an average diameter of about 40 nm. Immunostaining and ELISA assays using norovirus-specific human sera revealed that VLPs and the P domain are recognized by norovirus-specific antibodies and by their putative receptor. The VLPs and P domain protein are potentially useful in the development of diagnostic and vaccination tools for noroviruses.