The Role of Mammalian Reservoir Hosts in Tick-Borne Flavivirus Biology

Mlera, Luwanika; Bloom, Marshall E.

doi:10.3389/fcimb.2018.00298

Cited by 25 publications

(17 citation statements)

References 103 publications

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“…We therefore conclude that the different viruses we studied are not (or very rarely) transmitted to humans and cattle (<0.017% and <0.047%, respectively). Therefore, the six selected viruses may possibly either infect other vertebrates exposed to tick bites [and especially the role of rodents and migratory birds has to be evaluated, as regards to the trophic preference of ticks (Mlera and Bloom, 2018; Tomassone et al, 2018)], or be restricted to their tick hosts.…”

Section: Discussionmentioning

confidence: 99%

Monitoring Silent Spillovers Before Emergence: A Pilot Study at the Tick/Human Interface in Thailand

et al. 2019

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Emerging zoonoses caused by previously unknown agents are one of the most important challenges for human health because of their inherent inability to be predictable, conversely to emergences caused by previously known agents that could be targeted by routine surveillance programs. Emerging zoonotic infections either originate from increasing contacts between wildlife and human populations, or from the geographical expansion of hematophagous arthropods that act as vectors, this latter being more capable to impact large-scale human populations. While characterizing the viral communities from candidate vectors in high-risk geographical areas is a necessary initial step, the need to identify which viruses are able to spill over and those restricted to their hosts has recently emerged. We hypothesized that currently unknown tick-borne arboviruses could silently circulate in specific biotopes where mammals are highly exposed to tick bites, and implemented a strategy that combined high-throughput sequencing with broad-range serological techniques to both identify novel arboviruses and tick-specific viruses in a ticks/mammals interface in Thailand. The virome of Thai ticks belonging to the Rhipicephalus, Amblyomma, Dermacentor, Hyalomma, and Haemaphysalis genera identified numerous viruses, among which several viruses could be candidates for future emergence as regards to their phylogenetic relatedness with known tick-borne arboviruses. Luciferase immunoprecipitation system targeting external viral proteins of viruses identified among the Orthomyxoviridae, Phenuiviridae, Flaviviridae, Rhabdoviridae, and Chuviridae families was used to screen human and cattle Thai populations highly exposed to tick bites. Although no positive serum was detected for any of the six viruses selected, suggesting that these viruses are not infecting these vertebrates, or at very low prevalence (upper estimate 0.017% and 0.047% in humans and cattle, respectively), the virome of Thai ticks presents an extremely rich viral diversity, among which novel tick-borne arboviruses are probably hidden and could pose a public health concern if they emerge. The strategy developed in this pilot study, starting from the inventory of viral communities of hematophagous arthropods to end by the identification of viruses able (or likely unable) to infect vertebrates, is the first step in the prediction of putative new emergences and could easily be transposed to other reservoirs/vectors/susceptible hosts interfaces.

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Section: Discussionmentioning

confidence: 99%

Monitoring Silent Spillovers Before Emergence: A Pilot Study at the Tick/Human Interface in Thailand

et al. 2019

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“…The virus is endemic in forest and grassland areas, where it is transmitted to a multitude of animal species. Among them, small mammalians are suspected to be of importance for TBEV circulation, enabling the virus to be spread among the tick population [57]. To better understand the interaction between TBEV and its putative natural hosts, the virus–host interaction was studied under experimental conditions using European strains of TBEV in Central and Carpathian European voles.…”

Section: Discussionmentioning

confidence: 99%

In Vivo Characterization of Tick-Borne Encephalitis Virus in Bank Voles (Myodes glareolus)

Michelitsch

Tews

Klaus

et al. 2019

Viruses

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Tick-borne encephalitis is the most important tick-transmitted zoonotic virus infection in Eurasia, causing severe neurological symptoms in humans. The causative agent, the tick-borne encephalitis virus (TBEV), circulates between ticks and a variety of mammalian hosts. To study the interaction between TBEV and one of its suspected reservoir hosts, bank voles of the Western evolutionary lineage were inoculated subcutaneously with either one of eight TBEV strains or the related attenuated Langat virus, and were euthanized after 28 days. In addition, a subset of four strains was characterized in bank voles of the Carpathian linage. Six bank voles were inoculated per strain, and were housed together in groups of three with one uninfected in-contact animal each. Generally, most bank voles did not show any clinical signs over the course of infection. However, one infected bank vole died and three had to be euthanized prematurely, all of which had been inoculated with the identical TBEV strain (Battaune 17-H9, isolated in 2017 in Germany from a bank vole). All inoculated animals seroconverted, while none of the in-contact animals did. Viral RNA was detected via real-time RT-PCR in the whole blood samples of 31 out of 74 inoculated and surviving bank voles. The corresponding serum sample remained PCR-negative in nearly all cases (29/31). In addition, brain and/or spine samples tested positive in 11 cases, mostly correlating with a positive whole blood sample. Our findings suggest a good adaption of TBEV to bank voles, combining in most cases a low virulence phenotype with detectable virus replication and hinting at a reservoir host function of bank voles for TBEV.

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“…Within the Flaviviridae family, several tick-borne flaviviruses (TBFV) utilize rodents and other small mammals in their maintenance cycle. Tick-borne encephalitis virus, Omsk hemorrhagic fever virus, Kyasanur Forest virus, Apoi virus, and Powassan encephalitis virus are well-studied examples [ 18 , 19 , 20 , 21 , 22 ]. However, there have been isolations of flaviviruses that suggest the existence of transmission cycles involving rodents outside of the TBFV clade; one example being the isolation of Koutango virus from Tatera kempi (Kemp’s gerbil) in 1968 [ 23 ].…”

Section: Introductionmentioning

confidence: 99%

Usutu Virus Isolated from Rodents in Senegal

Diagne

Ndione

Paola

et al. 2019

Viruses

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Usutu virus (USUV) is a Culex-associated mosquito-borne flavivirus of the Flaviviridae family. Since its discovery in 1959, the virus has been isolated from birds, arthropods and humans in Europe and Africa. An increasing number of Usutu virus infections in humans with neurological presentations have been reported. Recently, the virus has been detected in bats and horses, which deviates from the currently proposed enzootic cycle of USUV involving several different avian and mosquito species. Despite this increasing number of viral detections in different mammalian hosts, the existence of a non-avian reservoir remains unresolved. In Kedougou, a tropical region in the southeast corner of Senegal, Usutu virus was detected, isolated and sequenced from five asymptomatic small mammals: Two different rodent species and a single species of shrew. Additional molecular characterization and in vivo growth dynamics showed that these rodents/shrew-derived viruses are closely related to the reference strain (accession number: AF013412) and are as pathogenic as other characterized strains associated with neurological invasions in human. This is the first evidence of Usutu virus isolation from rodents or shrews. Our findings emphasize the need to consider a closer monitoring of terrestrial small mammals in future active surveillance, public health, and epidemiological efforts in response to USUV in both Africa and Europe.

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The Role of Mammalian Reservoir Hosts in Tick-Borne Flavivirus Biology

Cited by 25 publications

References 103 publications

Monitoring Silent Spillovers Before Emergence: A Pilot Study at the Tick/Human Interface in Thailand

Monitoring Silent Spillovers Before Emergence: A Pilot Study at the Tick/Human Interface in Thailand

In Vivo Characterization of Tick-Borne Encephalitis Virus in Bank Voles (Myodes glareolus)

Usutu Virus Isolated from Rodents in Senegal

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