Recent developments in vaccines and biological therapies against Japanese encephalitis virus.

INTRODUCTION: Japanese encephalitis is the most common vaccine-preventable encephalitis in the Asia-Pacific region. AREAS COVERED: We provide an overview on Japanese encephalitis virus and associated disease, review the results of studies on the immunogenicity and efficacy of the licensed vaccines, and describe the new vaccines that are under development. We also discuss data on candidate anti-Japanese encephalitis drugs that have shown promising results in experimental models. EXPERT OPINION: The global burden of the Japanese encephalitis and associated mortality is still high, thus emphasizing the need to achieve the highest vaccination coverage in endemic areas. Clinical trials exhaustively demonstrated the safety and efficacy of current Japanese encephalitis vaccines. In addition, several new vaccine candidates, characterized by high immunogenicity and broad cross-protection, have been developed and evaluated in experimental models, warranting further clinical testing. No licensed anti-Japanese encephalitis drugs are available, notwithstanding intense research efforts. Some candidate antiviral agents that inhibit viral entry and replication have been identified, including compounds with broad-spectrum antiviral activity. Further research is needed to refine candidate compounds into drugs suitable for clinical evaluation, characterized by low toxicity, ability to penetrate the blood-brain barrier, activity during the late phase of infection, and high genetic barrier to resistance.