부산대학교 도서관

The Culex vishnui subgroups, particularly Culex tritaeniorhynchus, are considered the primary vectors of the Japanese encephalitis virus (JEV) in Asia. Recent molecular phylogenetic analyses of JEV isolates from Asian countries have shown that JEVs with diverse genetic variants are present in Asia. Furthermore, some JEV strains have been found to have crossed the East China Sea and been introduced into Japan. In this study, the possibility of overseas migration of the JE vector mosquito, Cx. tritaeniorhynchus was examined from the genetic, physical, and meteorological perspectives. Molecular phylogenetic analysis was performed based on both whole coding sequences and on the barcoding region of the mitochondrial cytochrome c oxidase subunit I (COI) gene of Cx. vishnui subgroups collected from Asian countries. Culex tritaeniorhymchus was classified into two genetically independent taxa by COI sequences: the Japanese type (Ct-J), which inhabits Japan except for the Amami Islands of southern Japan, and the continental type (Ct-C), which inhabits the Asian region except for Japan. It was confirmed that approximately 10% of Cx. tritaeniorhynchus trapped during the summer in western Kyushu were Ct-C, and that they could fly for up to 38 h continuously. The meteorological analysis also confirmed that the atmospheric flow occurring over the continent coincided with the date of Ct-C capture. This is the first report showing the existence of two taxa in Cx. tritaeniorhynchus. Their physical and physiological characteristics suggest the possibility of long-distance migration from overseas regions to Japan across the East China Sea. Future efforts are expected to provide evidence to support the occurrence of long-distance migration of Cx. tritaeniorhynchus with JEV. Author summary: We have been conducting research and studies on the importance of understanding the biological characteristics of each vector species in order to eradicate vector-borne diseases. In recent years, most reported cases of mosquito-borne diseases in Japan, such as dengue fever, malaria, and chikungunya fever, are imported cases from overseas; however, Japanese encephalitis (JE) is the only mosquito-borne disease for which autochthonous cases have been confirmed. The primary vector of JE virus (JEV) in Asia, a species called Culex tritaeniorhynchus, has long been recognized as a single species, however, this study is the first to report the existence of a cryptic species that is genetically distinct from Culex tritaeniorhynchus. Although long-distance migration of this species has been suspected for a long time, it has never been experimentally verified, and its contribution to the spread of JEV has not been investigated. The present study is also the first to confirm the capability of long-distance migration of this species biologically and physically, and to support it with meteorological data. Our objectives are to contribute to the prediction and minimization of the JE epidemic in Asia based on the results of experiments using the latest molecular genetic techniques combined with detailed physiological investigations. [ABSTRACT FROM AUTHOR]