1. A production method for Norovirus virus-like particles (VLPs), comprising:transforming insect cells with a baculovirus vector containing a viral nucleic acid sequence encoding a Norovirus major capsid protein VP1;
cultivating the insect cells in a medium thereby expressing the VLPs in the medium;
stopping cultivation when the viability of the insect cells reaches 20% or less; and
isolating supernatant comprising the VLPs from the insect cells thus producing the VLPs.