Studies on Japanese encephalitis virus infection of reptiles. II. Role of lizards on hibernation of Japanese encephalitis virus.

A series of experiments on the role of lizards as overwintering hosts of Japanese encephalitis virus (JEV) was carried out. Two species of lizards, T. tachydromoides and E. latiscutatus, 2 species of mosquitoes, Cx. p. fatigans and Cx. p. pallens, and 2 strains of JEV, JaGAr#01 and JaGAr 19461, were used in this study. Firstly transmission of JEV from infected mosquitoes to uninfected lizards and from infected lizards to normal mice by the bite of mosquitoes was demonstrated successfully. Cx. pipiens group mosquitoes were found to feed readily on lizards as compared to Cx. tritaeniorhynchus, the primary vector of JEV in Japan. Secondly simulated hibernation of JEV in lizards was carried out under indoor and outdoor conditions. In the outdoor hibernation, lizards were injected with JEV on October 14, 1968, entered in hibernation on October 19 and were recovered from hibernation on April 10, 1969. Viremias were demonstrated in the lizards for a few weeks in late April. Thirdly JEV isolation and HI antibody detection were attempted from blood samples of field-caught reptiles, 7 species of snakes and 3 species of lizards and among amphibians, 2 species of frogs. HI antibody against JEV was found at a rate of 14.3% from E. latiscutatus and 4.0% from T. tachydromoides, though JEV was not isolated from all the blood samples of these cold-blooded animals. The roles of lizards as overwintering hosts of JEV were discussed.