Susceptibility of Indigenous and Transplanted Mosquito Spp. to Dengue Virus in Japan

Abstract

SUMMARY: Dengue fever, an acute, mosquito-borne, febrile illness caused by Flavivirus spp., is a problem in Africa, South and Southeast Asia, Latin America, and the Caribbean. A dengue outbreak occurred after nearly 70 years of absence or no detection, and then 158 autochthonous cases occurred in Japan from August to October 15, 2014. The most competent mosquito vectors for dengue virus transmission were Aedes aegypti and A. albopictus. Since A. albopictus is widely distributed across Japan and A. aegypti recently invaded Japan by airplane, we examined the susceptibility of these species to infection by dengue virus.Dengue virus (DENV), which is transmitted by Aedes mosquitoes, is a global public health concern associated with an average of 390 million infections annually, 96 million of which are severe (1). In Japan, 249 cases of imported dengue fever were reported in 2013 (2). A. albopictus is present in Japan, and in August 2012, invasion of the yellow fever mosquito, A. aegypti, was reported at Narita International Airport (3) and then at Haneda International Airport in early to mid-2013 (personal communication). Moreover, in late August 2013, a single DENV infection was confirmed in a German individual travelling to Japan (4,5). In this study, we demonstrated the susceptibility of foreign (imported) and Japanese (indigenous) Aedes mosquito spp. to DENV infection. Although, A. aegypti has been compared with A. albopictus in DENV-infection experiments by Vazeille et al., a quantitative analysis of the salivary glands (SG), which are known to facilitate DENV transmission, was not performed (6). Furthermore, there are no reports of DENV1-transmission experiments in the literature (6). Furthermore, we must be careful while interpreting the results of our studies when using A. albopictus colonies with greater than F40 generations for DENV2-transmission experiments, as described by Vazeille et al. (6).Although, DENV2 antigen has been detected in the SG of A. aegypti, a quantitative analysis failed to confirm these findings (7). In addition, a quantitative realtime reverse transcription-polymerase chain reaction (qRT-PCR) analysis failed to show DENV1 transmission (8).For the DENV-transmission experiments, we used DENV1, D1 (11-120), isolated from the serum of a returnee from Bangkok, Thailand, and DENV2, D2 (11-122/1), isolated from the serum of a returnee from Bali, Indonesia (both provided by the Department of Virology I, National Institute of Infectious Diseases). The experimental mosquitoes were A. aegypti, LBN strain, collected in Los Banos, Philippines (2011); A. albopictus IKT strain, collected in Kawasaki, Kanagawa Prefecture, Japan (2008); A. albopictus EBN strain, collected in Ebina, Kanagawa Prefecture, Japan (2012); and A. albopictus HCM strain, collected in Ho Chi Minh, Vietnam (2013). Four-to five-day-old adult mosquitoes were orally infected with DENV by exposure to blood mixed with 10 5 copies/mL of DENV in artificial membrane feeders. After 1 h of feeding, the mosquitoes were maintained at 289 C f...

Dengue Virus Infection in Aedes albopictus during the 2014 Autochthonous Dengue Outbreak in Tokyo Metropolis, Japan

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Differential Small RNA Responses against Co-Infecting Insect-Specific Viruses in Aedes albopictus Mosquitoes

“…Laboratory colonies of Ae. albopictus were established using field-collected mosquitoes from Binh Duong Province, Vietnam (2011) [46] and Kawasaki, Kanagawa Prefecture Japan (2008) [47]. All the experiments were performed within 16-20 and 45-50 generations of laboratory colonization for the Vietnamese and Japanese mosquito colonies, respectively.…”

Vertebrate Reservoirs of Arboviruses: Myth, Synonym of Amplifier, or Reality?

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