A vaccine composition for humans and animals against Japanese encephalitis virus infection is a composition which comprises a chimeric synthetic peptide selected from envelope glycoprotein consisting of amino acids Egp 149-SENHGNYSAQVGASQ-163 (SEQ ID NO:1) AND Egp 429-SIGGVFNSIGKAVHQVFG-446 (SEQ ID NO:2) of Japanese encephalitis virus envelope glycoprotein, present in an amount sufficient to induce protective immunity against Japanese encephalitis virus infection.