Kyoko Sawabe's research while affiliated with The National Institute of Infectious Diseases and other places
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Publications (229)
High pathogenicity avian influenza (HPAI) poses a significant threat to both domestic and wild birds globally. The avian influenza virus, known for environmental contamination and subsequent oral infection in birds, necessitates careful consideration of alternative introduction routes during HPAI outbreaks. This study focuses on blowflies (genus Ca...
During their blood-feeding process, ticks are known to transmit various viruses to vertebrates, including humans. Recent viral metagenomic analyses using next-generation sequencing (NGS) have revealed that blood-feeding arthropods like ticks harbor a large diversity of viruses. However, many of these viruses have not been isolated or cultured, and...
In Asia, Culex mosquitoes are of particular interest because of their role in maintaining endemic mosquito-borne viral diseases, including the Japanese encephalitis virus (JEV). Nonetheless, host-feeding preferences, along with naturally infecting RNA viruses in certain Culex species, remain understudied. In this study, selected blood-fed mosquitoe...
Bartonella quintana is a gram-negative bacterium causing trench fever, an illness historically acquired by soldiers during World War I. More recently, outbreaks of trench fever have been reported in those experiencing homelessness in the United States, France, Russia, and Tokyo, as well as in children in Nepal and persons in Ethiopia. Reports of B....
Genotype IV Japanese encephalitis (JE) virus (GIV JEV) is the least common and most neglected genotype in JEV. We evaluated the growth and pathogenic potential of the GIV strain 19CxBa-83-Cv, which was isolated from a mosquito pool in Bali, Indonesia, in 2019, and serological analyses were also conducted. The growth ability of 19CxBa-83-Cv in Vero...
[This corrects the article DOI: 10.1371/journal.pntd.0008986.].
Aedes aegypti (Linnaeus, 1762) is the main mosquito vector for dengue and other arboviral infectious diseases. Control of this important vector highly relies on the use of insecticides, especially pyrethroids. The high frequency (>78%) of the L982W substitution was detected at the target site of the pyrethroid insecticide, the voltage-gated sodium...
Eleven species and three genera of tabanid flies were collected through surveys conducted at the Noto Peninsula, Honshu, Japan. Of these, Silvius dorsalis, Tabanus coquilletti, and T. fulvimedioides were collected as newly recorded species from the peninsula. Combined with previous records, a total of 16 species belonging to four genera of tabanid...
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 h...
Japanese encephalitis virus (JEV), a mosquito-borne virus, causes severe clinical symptoms in humans in the Asian-Pacific region, where it circulates in a primary transmission cycle among Culex tritaeniorhynchus mosquitoes, domestic swine ( Sus scrofa domesticus ), and wading birds. We report here an anomalous result that mosquito-borne JEV was det...
To investigate the current mosquito fauna on Sado Island, we conducted surveillance in the Oosado mountainous area and the Kuninaka plain area from July 30 to August 3, 2019. In total, 20 species belonging to nine genera were collected. Among these, nine species in six genera were newly recorded on Sado Island. We also determined partial nucleotide...
Aedes aegypti (Linnaeus, 1762) is the main mosquito vector for dengue and other arboviral infectious diseases. Control of this important vector highly relies on the use of insecticides, especially pyrethroids. Nevertheless, the development of pyrethroid resistance is a major obstacle to mosquito/disease control worldwide. Here, we focused on the mu...
Oz virus is a novel thogotovirus isolated from ticks that causes lethal infection in mice. We conducted serosurveillance of Oz virus infection among humans and wild mammals in Japan using virus-neutralization tests and ELISAs. Results showed that Oz virus may be naturally infecting humans and other mammalian hosts.
Ticks are blood-sucking arthropods that transmit many pathogens, including arboviruses. Arboviruses transmitted by ticks are generally referred to as tick-borne viruses (TBVs). TBVs are known to cause diseases in humans, pets, and livestock. There is, however, very limited information on the occurrence and distribution of TBVs in sub-Saharan Africa...
Thirty years have passed since the last surveillance of the mosquito fauna on the entire Chichi-jima, Ogasawara Islands, Japan. Herein, we report the results of a mosquito study conducted on the Ogasawara Islands in 2015 and 2017. In this study, 2,371 individuals belonging to seven species in three genera were collected, including 262 mosquitoes be...
The emergence of pyrethroid resistance in Phlebotomus sandflies is an urgent issue for vector control using indoor residual spraying (IRS). Two amino acid substitutions at codon 1014 (L1014F and L1014S) in the voltage-gated sodium channel (VGSC) gene have been reported in Phlebotomus argentipes, a major vector of visceral leishmaniasis (VL). Known...
Jingmen tick virus (JMTV) and the related jingmenvirus-termed Alongshan virus are recognized as globally emerging human pathogenic tick-borne viruses. These viruses have been detected in various mammals and invertebrates, although their natural transmission cycles remain unknown. JMTV and a novel jingmenvirus, tentatively named Takachi virus (TAKV)...
Kabuto Mountain virus (KAMV), the new member of the genus Uukuvirus, was isolated from the tick Haemaphysalis flava in 2018 in Japan. To date, there is no information on KAMV infection in human and animals. Therefore, serological surveillance of the infection among humans and wild mammals was conducted by virus-neutralization (VN) test and indirect...
Ticks are important vector arthropods that transmit various pathogens to humans and other animals. Tick-borne viruses are of particular concern to public health as these are major agents of emerging and re-emerging infectious diseases. The Phenuiviridae family of tick-borne viruses is one of the most diverse groups and includes important human path...
Background
In Hokkaido, northern island of Japan, at least seven cases of falciparum malaria were reported by 1951. A survey conducted at that time was unsuccessful in implicating any mosquito species as the possible vector. Although active anopheline mosquito surveillance continued until the middle of the 1980s, there is very limited information o...
Viruses belonging to the genus Quaranjavirus in the family Orthomyxoviridae are known as argasid tick-borne viruses. Some viruses in this genus or an unassigned quaranjavirus-like virus have the ability to infect humans although little is known about their pathogenicity. During the surveillance of tick-borne viruses in ixodid ticks in Ehime Prefect...
From August 27 to October 15, 2014, a dengue fever outbreak with 158 autochthonous cases occurred after nearly 70 years of no reports of autochthonous cases in Japan. The most competent mosquito vector for dengue virus (DENV) transmission in Japan is Aedes albopictus. Since A. albopictus is widely distributed throughout Japan, we examined the susce...
Japanese encephalitis virus (JEV) is transmitted between swine, migratory birds, and Culex mosquitoes, and has circulated indigenously in Asia for almost a century. Despite being the country with the highest JEV diversity, surveillance targeting of Indonesia's vectors is scarce. This study collected mosquitoes from several locations in Tabanan Rege...
Background: After World War II in Hokkaido, northern island of Japan, at least seven cases of falciparum malaria were reported by 1951. A survey conducted at that time was unsuccessful in implicating any mosquito species as the possible vector. Although active anopheline mosquito surveillance continued until the middle of the 1980s, there is very l...
Background: In Hokkaido, northern island of Japan, at least seven cases of falciparum malaria were reported by 1951. A survey conducted at that time was unsuccessful in implicating any mosquito species as the possible vector. Although active anopheline mosquito surveillance continued until the middle of the 1980s, there is very limited information...
Background:
Dengue virus (DENV) is a mosquito-borne arbovirus transmitted by Aedes mosquitoes, but is not endemic in all areas where this vector is found. For example, the relatively sparse distribution of cases in West Africa is generally attributed to the refractory nature of West African Aedes aegypti (Ae. aegypti) to DENV infection, and partic...
BACKGROUND
Aedes aegypti is a remarkably effective mosquito vector of epidemiologically important arboviral diseases including dengue fever, yellow fever and Zika. The present spread of resistance against pyrethroids, the primary insecticides used for mosquito control, in global populations of this species is of great concern. The voltage‐gated sod...
Several outbreaks of trench fever caused by Bartonella quintana, occurred in soldiers during World Wars I and II. Although the number of trench fever cases has been decreasing worldwide, the disease has been reported among the homeless population in both developing and developed countries. The current prevalence of B. quintana infection in Japan is...
Viruses are highly diverse and are the sole agents that can infect organisms in all domains of life. Viruses are defined as capsid-encoding organisms as opposed to ribosome-encoding cellular organisms. However, recent advances in virology indicate the existence of unique viruses that do not meet this basic definition, such as capsidless viruses. Du...
Japanese encephalitis virus (JEV) is maintained in an enzootic cycle between swine, water birds, and mosquitoes. JEV has circulated indigenously in Asia, with Culex tritaeniorhynchus as the primary vector. In some areas where the primary vector is scarce or absent, sporadic cases of Japanese encephalitis have been reported, with Aedes japonicus jap...
Nagano Prefecture, an inland mountain area of Japan, extends widely north and south, with elevation that varies greatly by location. Mosquitoes transmitting infectious disease have a diversity of habitats in Nagano, and many species can be expected there. However, there have been few reports about mosquito fauna in this region; in particular, littl...
Trypanosoma are known to be a diverse group of parasites that infect animals belonging to all classes in the subphylum Vertebrata and are important pathogens that affect human and animal health. Although many trypanosomatids have been found in mammals and birds in Japan, information regarding their invertebrate host is currently lacking. During our...
Tabanid flies (Tabanidae: Diptera) are common hematophagous insects known to transmit some pathogens mechanically or biologically to animals; they are widely distributed throughout the world. However, no tabanid-borne viruses, except mechanically transmitted viruses, have been reported to date. In this study, we conducted RNA virome analysis of sev...
The development of sequencing technologies, in recent years, gives novel insights into the diversity of viruses in arthropods. Human pathogenic or possible pathogenic arthropod-borne viruses (arboviruses) including novel viruses from mosquitoes and ticks have been found by RNA virome analysis using a high-throughput sequencer. However, virome studi...
Mosquitoes are generally considered one of the most important vectors of arboviruses, with Aedes aegypti regarded as the most important in transmission of yellow fever and dengue viruses. To investigate why there are differences in the incidence of dengue fever and Zika in different geographical areas and an absence of outbreaks in Ghana in spite o...
From 2013 to 2014, ixodid ticks (Acari: Ixodidae) were collected by flagging at seven sites of two areas, Noto and Kaga, in Ishikawa Prefecture, Honshu, Japan. As a result of the survey, the following four ixodid species were collected: Haemaphysalis flava, Haemaphysalis longicornis, Ixodes ovatus, and Ixodes turdus. This is the first record of I....
In preparation for the 2020 Olympic and Paralympic Games in Tokyo, a training drill for controlling dengue mosquito vector was held at Shinjuku Gyoen National Garden in September 2019. The training drill aimed to confirm the network and cooperation among related organizations when pathogenic arboviruses are detected in mosquito vectors. This traini...
Mosquitoes transmit many kinds of arboviruses (arthropod-borne viruses), and numerous arboviral diseases have become serious problems in Indonesia. In this study, we conducted surveillance of mosquito-borne viruses at several sites in Indonesia during 2016–2018 for risk assessment of arbovirus infection and analysis of virus biodiversity in mosquit...
Non-enveloped icosahedral double-stranded RNA (dsRNA) viruses possess multifunctional capsids required for their proliferation. Whereas protozoan/fungal dsRNA viruses have a relatively simple capsid structure, which suffices for the intracellular phase in their life cycle, metazoan dsRNA viruses have acquired additional structural features as an ad...
The introduction of exotic disease vectors into a new habitat can drastically change the local epidemiological situation. During 2012–2015, larvae and an adult of the yellow-fever mosquito, Aedes aegypti, were captured alive at two international airports serving the Greater Tokyo Area, Japan. Because this species does not naturally distribute in th...
We have faced a number of outbreaks of arthropod-borne infectious diseases in Japan and aimed to address each case appropriately. Here, I introduce two arthropod-borne infectious diseases caused by flies and mosquitoes, respectively. In 2004, the highly pathogenic avian influenza occurred in Kyoto. The H5N1 influenza A virus was isolated from the b...
Nagano and Yamanashi prefectures of Japan comprise an inland mountain area that extends widely north and south, with elevation varying greatly by location. Mosquitoes transmitting infectious disease have a diversity of habitats in Nagano and Yamanashi, and many species can be expected there. However, there have been few reports on mosquito fauna; i...
Japanese encephalitis (JE) remains a public health concern in several countries, and the Culex mosquito plays a central role in its transmission cycle. Culex mosquitoes harbor a wide range of viruses, including insect-specific viruses (ISVs), and can transmit a variety of arthropod-borne viruses (arboviruses) that cause human and animal diseases. T...
Entomological surveillance is one of the tools used in monitoring and controlling vector-borne diseases. However, the use of entomological surveillance for arboviral infection vector control is often dependent on finding infected individuals. Although this method may suffice in highly endemic areas, it is not as effective in controlling the spread...
Tick-borne viruses have emerged recently in many parts of the world, and the discoveries of novel tick-borne viruses have been accelerated by the development of high-throughput sequencing technology. In this study, a cost-efficient small benchtop next-generation sequencer, the Illumina MiniSeq, was used for the RNA virome analysis of questing ticks...
In insects, the voltage-gated sodium channel (VGSC) is the primary target site of pyrethroid insecticides. Various amino acid substitutions in the VGSC protein, which are selected under insecticide pressure, are known to confer insecticide resistance. In the genome, the VGSC gene consists of more than 30 exons sparsely distributed across a large ge...
During 2012-2015, live larvae and an adult of the yellow-fever mosquito, Aedes aegypti , were captured in two international airports serving the Greater Tokyo area of Japan. Because this species does not naturally distribute in this country, those mosquitoes were considered to be introduced from some foreign countries via air-transportation. To inf...
Cemeteries are suitable habitats for Aedes albopictus. The dispersal of adults emerging at a cemetery was studied by a mark-release-recapture experiment during the period July 11–15, 2016 in Okayama, Japan. Larvae and pupae of Ae. albopictus were collected from artificial containers found in the cemetery, reared to the adult stage, and used for the...
We investigated the occurrence of mosquitoes in both disaster areas of the 2011 Great East Japan earthquake and tsunami and the 2016 Kumamoto earthquake in the summers after the disasters respectively. In the former area, Culex pipiens group was the most common taxa in adult stage (157.01 individuals per trap per day; 82.55%). In larval stage, Cx....
Insects' voltage-gated sodium channel (VGSC) is the primary target site of pyrethroid insecticides. Various amino acid substitutions in the VGSC protein are known to confer insecticide resistance and are selected under insecticide pressure. In the genome, the VGSC gene consists of more than 30 exons sparsely distributed across a large genomic regio...
IntroductionAedes albopictus (Skuse) is an important vector of arboviral diseases, including dengue, chikungunya and Zika virus disease. Monitoring insecticide resistance and mechanisms by which the mosquito develops resistance is crucial to minimise disease transmission.AimTo determine insecticide resistance status and mechanisms in Ae. albopictus...
In the growth kinetics analysis of flaviviruses in Aedes albopictus C6/36 cell lines obtained from the Japanese Collection of Research Bioresources (JCRB) Cell Bank and the European Collection of Authenticated Cell Culture (ECACC), these two cells line showed different viral susceptibility for Zika virus (ZIKV), Dengue virus (DENV), and Japanese en...
In 2014 in Japan, 162 autochthonous dengue cases were reported for the first time in nearly 70 years. Here, we report the results of the detection and isolation of dengue virus (DENV) from mosquitoes collected in Tokyo Metropolis in 2014 and 2015. The phylogenetic relationship among DENV isolates from mosquitoes and from patients based on both the...
The genus Thogotovirus, as represented by Thogoto virus and Dhori virus, comprises a group of arthropod-borne viruses, most members of which are transmitted by ticks. Here we report the genetic and biological characterization of a new thogotovirus, designated Oz virus (OZV), isolated from the hard tick Amblyomma testudinarium in Ehime, Japan. OZV e...
In September 1995 it was reported that the redback spider (Latrodectus hasseltii Thorell) had invaded Japan. To date 84 redback spider bite cases have been reported, and of these, seven employed the antivenom. In the past, antivenom have been imported from Australia, but because of restrictions on exportation thereof it was evident that nearly all...
In Japan, indigenous tick-borne phleboviruses (TBPVs) and their associated diseases first became evident in 2013 by reported human cases of severe fever with thrombocytopenia syndrome (SFTS). In this study, we report a novel member of the genus Phlebovirus designated as Kabuto Mountain virus (KAMV), which was isolated from the ixodid tick Haemaphys...
Rhabdophis lateralis, a colubrid snake distributed throughout the continent of Asia, has recently undergone taxonomic revisions. Previously, Rhabdophis lateralis was classified as a subspecies of R. tigrinus (Yamakagashi) until 2012, when several genetic differences were discovered which classified this snake as its own species. To elucidate the to...
This is the first report of the large-scale experimentally production of an equine antivenom against redback spider (Latrodectus hasseltii) lived in Japan. We captured 10,000 redback spiders in Japan and prepared the toxoids of crude venom extract, mixed the toxoids with mineral oil adjuvant, and immunized repeatedly it to healthy horses over a per...
During an entomological surveillance for arthropod-borne viruses in the Philippines, we isolated a previously unrecognized virus from female Armigeres spp. mosquitoes. Whole-genome sequencing, genetic characterization and phylogenetic analysis revealed that the isolated virus, designated Armigeres iflavirus (ArIFV), is a novel member of the iflavir...
The suppressive effect of acaricides, including propetamphos MC (P-MC), fenthion/tetramethrin EC (FT-EC), fenitrothion FL (F-FL), and fenitrothion dust (F-D), on ticks in recreational areas was investigated in Hyogo Prefecture, Japan. The predominant species in the experimental area was Haemaphysalis longicornis. Following a single application in t...
Aedes albopictus (Skuse) (Diptera: Culicidae) is distributed widely and is common in much of Japan. In Japan, female adults begin to bite in between April and June, except in the southern subtropics where the mosquito has no dormant period. It is difficult to estimate the first Ae. albopictus biting day because it varies annually depending on the l...
During the course of tick-borne virus surveillance in Japan, three independent isolates of probably the same virus were obtained from three geographically distant populations of the hard tick Haemaphysalis flava. Genome analyses of the three isolates demonstrated that they were closely related but distinct strains of a novel virus, designated Tarum...
Blood serum from immunized humans or animals (e.g., horses) contains relevant antibodies and has been used as serum therapy to treat many diseases or envenomation events. The effectiveness of blood serum was initially discovered in 1890 when Kitasato and von Behring observed the effectiveness of this type of therapy against diphtheria and tetanus....
Ticks are ectoparasites that transmit various types of human and animal pathogens. In particular, emerging and re-emerging diseases caused by tick-borne viruses are public health concerns around the world. However, in many countries of the sub-Saharan African region, epidemiological information on tick-borne viral infections is limited, and their p...
We isolated two distinct viruses from mosquitoes collected in Bustos, Bulacan province, Philippines, in 2009. These viruses show rapid replication and strong cytopathic effects in mosquito C6/36 cells. Whole-genome analysis of these viruses demonstrated that both viruses belong to the negevirus group. One of the viruses, from Culex vishunui mosquit...
On 11 March 2011, a massive earthquake and resulting tsunamis caused widespread destruction across north-eastern Japan. To monitor potential population outbreaks resulting from the damage, occurrence of vector mosquitoes was continuously monitored until August 2015 in three cities: Rikuzentakata in Iwate Prefecture and Kesennuma, and Ishinomaki in...
In Japan, fourteen bites by the red back spider, Latrodectus hasselti, were reported in four hospitals between 2011 and 2013 in a survey of sentinel hospitals. The distribution of the spider and the areas in which patients were bitten by the spider both expanded geographically each year. Although fatalities or severely ill patients are yet to be re...
Getah virus (GETV; genus Alphavirus, family Togaviridae) is a mosquito-borne virus known to cause disease in horses and pigs. In 2014, for the first time in ∼30 years, a sudden GETV outbreak occurred among racehorses in Ibaraki, Japan. Two years before this outbreak, we obtained multiple GETV isolates from Culex tritaeniorhynchus mosquitoes collect...
Dengue virus (DENV) isolation from mosquitoes is necessary for providing definitive evidence of virus circulation, and is critical for further virological characterization and determination of epidemiological characteristics. By using Aedes albopictus mosquitoes captured during an outbreak in Tokyo in 2014, we compared the DENV isolation rates of a...
A total of 512 mosquito specimens, collected in 2013 and 2014 from 18 study sites from Hokkaido to Kagoshima, Japan, were analyzed for DNA barcoding based on the nucleotide sequence of cytochrome c oxidase subunit I (COI) region, following which the gene sequences of 240 mosquitoes from 45 species in 11 genera were registered in GenBank. Aedes mosq...
Omono River virus (OmRV) is a double-stranded RNA virus isolated from Culex mosquitos, and it belongs to a group of unassigned insect viruses that appear to be related to Totiviridae. This paper describes electron cryo-microscopy (cryoEM) structures for the intact OmRV virion to 8.9 Å resolution and the structure of the empty virus-like-particle, t...
We surveyed the fly emergence at 2 places of processing yards for disaster debris in Iwate Prefectrue in 2012 using sticky traps. After the tsunami of 2011 the Great East Japan Earthquake, a lot of flies were emerged and caused problem, but mass occurrence of flies were not observed there in 2012.
There are mainly three innate immunity mechanisms against viruses in mosquitoes. Infection by the flavivirus dengue virus is controlled by RNAi, the JAK–STAT, and Toll signaling pathways. Our studies of another flavivirus, Japanese encephalitis virus (JEV), showed that the virus was not highly infectious for the salivary glands of Aedes aegypti and...
Annual changes in the distribution and abundance of mosquitoes were studied in rice field areas of southern Miyagi and Minamisouma in Fukushima, Japan, where urban and rural environments were destroyed by the Tsunami caused by the Great East Japan Earthquake in 2011. A total of 16 species and species groups of mosquitoes were collected by dry-ice t...
The first confirmed dengue outbreak in nearly 70 years in Japan was reported in 2014 with 162 autochthonous dengue cases. The largest number of confirmed cases were reported in August and continued to be reported through October. Majority were associated with Yoyogi Park, a forested park popular with international and local visitors and an ideal si...
A nationwide survey of mosquito distribution in Japan was carried out in 2013 and 2014, in order to determine the current distribution of vector mosquitoes. Forty-two study sites located either in coastal or inland areas were selected from Hokkaido to Kyushu, and mosquitos were collected using CDC-like traps with 1 kg of dry ice (dry ice traps), a...
A field evaluation of the acaricidal effect on ticks was conducted in Chiba Prefecture in 2014. Eleven formulations of organophosphates and pyrethroids, including emulsifiable concentrate (EC), flowable (FL), dust and CO2 gas formulation, were evaluated simultaneously. These formulations were respectively applied to zones 2 m wide by 17–60 m long w...
Among the tick-borne orbiviruses (genus Orbivirus, family Reoviridae), 36 serotypes are currently classified within a single virus species, Great Island virus. In this study, we report the first characterization of a tick-borne orbivirus isolated from the tick Ixodes turdus in Japan, which we identified as a new member of the species Great Island v...
The objective of this study was to clarify the efficacy of a currently-available DEET repellent against tick species in Japan. We performed two different field trials: "human trap," and "flag-dragging." In total, 482 ticks were collected from white flannel cloths in field studies. The species of collected ticks consisted of Ixodes persulcatus and I...
An autochthonous dengue patient was confirmed on 8 September 2014 in Chiba City, Japan and emergency vector control of dengue fever against Aedes albopictus was implemented in the residential area where the case was found. We examined the distribution of human dwellings and areas with trees and bushes in the residential area by using an aerial phot...
Dengue fever is an acute, mosquito-borne, febrile illness caused by Flavivirus spp., which 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 158 autochthous cases occurred in Japan from August to October 15, 2014. The most competent mo...
A total of 160 autochthonous dengue cases transmitted by Aedes albopictus were reported from August to October 2014 in Tokyo Metropolis, Japan. Ae. albopictus is a medically important vector of dengue virus which has been expanding its geographic distribution in temperate regions. The understanding of the distribution and density of biting Ae. albo...
Armigeres subalbatus (Coquillett) is a medically important mosquito and a model species for immunology research. We successfully established two cell lines from the neonate larvae of A. subalbatus using two different media. To our knowledge, this is the first report of an established Armigeres mosquito cell line. The cell lines, designated as Ar-3...
Superinfection exclusion is generally defined as a phenomenon in which a pre-existing viral infection prevents a secondary viral infection; this has also been observed in infections with mosquito-borne viruses. In this study, we examined the superinfection exclusion of the vertebrate-infecting flaviviruses, Japanese encephalitis virus (JEV) and den...
A total of 162 autochthonous dengue cases were reported in Japan in 2014, after the absence of any such cases for approximately 70 years. During this period of dengue outbreak, vector control using an insecticide was performed for Aedes albopictus at almost all areas where dengue virus transmission was suspected.On March 28, 2015, an urgent symposi...
Redback spiders (Latrodectus hasselti) (RBSs) are venomous spiders that have recently spread to Asia from Australia. Since the first case report in 1997 (Osaka), RBS bites have been a clinical and administrative issue in Japan; however, the clinical characteristics and effective treatment of RBS bites, particularly outside Australia remains unclear...
A German traveler developed dengue fever in late August 2013, following a direct flight from Germany. Autochthonous dengue virus (DENV) infection has not been reported in Japan. To evaluate the risk of autochthonous DENV transmission in Japan, the authors performed a retrospective search of the five areas visited by the German patient to determine...
An orbivirus was isolated from a sample from the ornithophilic mosquito Culex sasai in Japan. The virus, designated Koyama Hill virus (KHV), replicated to high titer in a mosquito cell line and to a low titer in an avian cell line, but the release of progeny viruses was not observed in mammalian cell lines inoculated with KHV. Electron microscopic...
Citations
... Ae. albopictus is an opportunistic feeder that mainly prefers mammals but sometimes also feeds on reptiles and birds as a blood source (Richards et al., 2006;Sawabe et al., 2010); all of these can act as the natural JEV reservoirs (Doi et al., 1983;Faizah et al., 2023;Shortridge et al., 1974). Additionally, their short EIP, a critical parameter that greatly influences vectorial capacity, may increase vector-borne illness outbreaks. ...
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... Efforts to develop treatments for JEV neuropathology are hindered by the difficulties in diagnosing early infection 13 before the virus has infected central nervous system (CNS) neurons; and once the virus has infected CNS neurons, treatments must also be able to effectively enter the brain. While a range of JEV mouse models have been reported (Supplementary Table 1) 19 , there are no studies of genotype 4 peripheral inoculation in adult mice, with the only studies on genotype 4 JEV using 3-week-old mice 20 or intracranial inoculation 21 . Well-characterized, adult mouse models of recent genotype 4 isolates would represent useful tools to study mechanisms of infection and disease and evaluate potential new interventions. ...
... However, disease prevention for humans and livestock can be achieved through health measures and vaccination. In addition, as a natural focus disease transmitted by mosquitoes, the incidence of JE will be affected by climate factors such as temperature and rainfall [2,[23][24][25]. ...
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... We did not observe any other pyrethroid resistance associated substitutions such as L982W, detected previously in Vietnam and Cambodia, and D1763Y reported in Taiwan. However, the D1763G mutation was present in a single USA sample 11,[16][17][18] . The most frequent mutations were F1534C (39%), S723T (23%), V410L (22%) and V1016I (22%) (Fig. 2). ...
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... Analysis of the RNA viromes of 10 Culicoides species in Thrace, southeastern Europe, led to the identification of novel RNA viruses with genomic signatures and revealed that each Culicoides species carried a specific virus set (32). The viromes of Culicoides impunctatus populations in Scotland (33), Culicoides imicola in Senegal (34), Culicoides arakawae in Japan (35), and mixed Culicoides populations (6,36) have been examined. ...
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... We did not have vaccination records for all individuals, and our evaluation of vaccine effectiveness relied solely on the risk of the birth cohort. Furthermore, the scope of investigation by local health authorities regarding exposure to pigs, pigeons, and rice paddy fields might not have been extensive enough given the long-distance migration ability of C. tritaeniorhynchus [38]. To address this, we assessed the occupational risk of agriculture, forestry, fishing, and animal husbandry workers to evaluate the exposure risk. ...
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... Unnatural viruses of vertebrates or arthropods are sometime found in ticks or mosquitoes as a result of sucking blood of infected hosts, even though these viruses do not replicate in each group of respective vectors. The examples in ticks include rabies virus [166], corona virus [167], Tacaribe virus (an arenavirus) [168], murine herpes virus [169], and JEV [170]. Conversely, possible mechanical transmission of lymphocytic choriomeningitis virus [171], Burkitt's lymphoma [172], Hepatitis B virus [173], and HIV [174] by mosquitoes was once topics of controversy. ...
... Four amino-acid substitutions (V977L, K1577T, N1595T, P1612H) were found in vgsc gene. Of interest is the substitution V977L as it is next to a known mutation, L978W, (homologous to position L982W in Drosophila melanogaster), which is reported to confer resistance to pyrethroids [48,49]. ...
... They transmit diseases through blood-sucking bites or contact with the host's body fluids, blood, or animal products (Huang et al. 2020). The pathogens they carry can cause symptoms such as nausea, headache, fever, cytopenias (Wang et al. 2019), and diseases such as meningitis and hemorrhagic fever (Bonnet et al. 2022), and even death (Tran et al. 2022). The small genome, stable genetic composition, and maternal inheritance are remarkable characteristics found within the mitochondria of insects (Yang et al. 2022). ...
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... To date, the COI gene sequences of 74 of 122 Japanese mosquito species have been registered in GenBank (Taira et al., 2012;Maekawa et al., 2016bMaekawa et al., , 2021. For further understanding of the genetic and geographic variations of Japanese mosquitoes, it is necessary to accumulate more information on COI gene sequences of Japanese mosquitoes including 48 species that have not yet been subjected to DNA studies. ...
