Molecular detection and identification of Culex flavivirus in mosquito species from Jeju, Republic of Korea

Background Mosquito-borne flaviviruses are prime pathogens and have been a major hazard to humans and animals. They comprise several arthropod-borne viruses, including dengue virus, yellow fever virus, Japanese encephalitis virus, and West Nile virus. Culex flavivirus (CxFV) is a member of the insect-specific flavivirus (ISF) group belonging to the genus Flavivirus, which is widely distributed in a variety of mosquito populations. Methods Viral nucleic acid was extracted from adult mosquito pools and subjected to reverse transcriptase nested polymerase chain reaction (PCR) using target-specific primers for detecting CxFV nonstructural protein 5 (NS5). The PCR-positive samples were then sequenced, and a phylogenetic tree was constructed, including reference sequences obtained from GenBank. Results 21 pools, belonging to Culex pipiens pallens (Cx. p. pallens) were found to be positive for the CxFV RNA sequence, with a minimum infection rate of 14.5/1000 mosquitoes. The phylogenetic analysis of the NS5 protein sequences indicated that the detected sequences were closely related to strains identified in China, with 95-98% sequence similarities. Conclusion Our findings highlight the presence of CxFV in Cx. p. pallens mosquito species in Jeju province, Republic of Korea. This is the first study reporting the prevalence of CxFV in Culex Pipiens (Cx. pipiens) host in the Jeju province, which can create possible interaction with other flaviviruses causing human and animal diseases. Although, mosquito-borne disease causing viruses were not identified properly, more detailed surveillance and investigation of both the host and viruses are essential to understand the prevalence, evolutionary relationship and genetic characteristic with other species.