A highly quantitative detection system for cell entry of human norovirus-like particles based on the complementation of NanoLuc luciferase.

Human norovirus (HuNoV) is the common cause of acute gastroenteritis worldwide. Norovirus-like particles (VLPs) have been applied to analyze virus-host cell interactions. This study established a highly quantitative detection system for HuNoV VLP entry into live cells based on the NanoLuc luciferase complementation. First, we generated a HiBiT-tagged VLP and examined VLP-HiBiT entry into Vero cells expressing LgBiT. The entry was saturable and competed by a non-labeled VLP, indicating the VLP-specific entry into the host cells. Upon comparison of the VLP-HiBiT entry among some cell lines, Caco-2 cells were found to be the most susceptible. The VLP-HiBiT entry was unaffected by treatment at an acidic pH value above 3.0 and was significantly reduced by heat treatment at 75°C for more than 2 min. These results reflected those of previous studies, indicating the stability of VLPs and binding to histo-blood group antigens at various pH ranges and temperatures and cellular tropism.