<;P>;PROBLEM TO BE SOLVED: To provide a low-cost Japanese encephalitis vaccine using neither mouse brain nor virus, alternative to inactivated Japanese encephalitis virus being in use in the current Japanese encephalitis vaccine. <;P>;SOLUTION: A Japanese encephalitis virus antigen including Japanese encephalitis virus-like particles is provided. In this antigen, the virus-like particles consist of protein aggregate which include the M-protein and E-protein of Japanese encephalitis virus but no RNA, and the virus-like particles are characterized by exhibiting erythrocyte coagulation activity. <;P>;COPYRIGHT: (C)2009,JPO&INPIT