Evaluation of two artificial infection methods of live ticks as tools for studying interactions between tick-borne viruses and their tick vectors

AbstractUp to 170 tick-borne viruses (TBVs) have been identified to date. However, there is a paucity of information regarding TBVs and their interaction with respective vectors, limiting the development of new effective and urgently needed control methods. To overcome this gap of knowledge, it is essential to reproduce transmission cycles under controlled laboratory conditions. In this study we assessed an artificial feeding system (AFS) and an immersion technique (IT) to infect Ixodes ricinus ticks with tick-borne encephalitis (TBE) and Kemerovo (KEM) virus, both known to be transmitted predominantly by ixodid ticks. Both methods permitted TBEV acquisition by ticks and we further confirmed virus trans-stadial transmission and onward transmission to a vertebrate host. However, only artificial feeding system allowed to demonstrate both acquisition by ticks and trans-stadial transmission for KEMV. Yet we did not observe transmission of KEMV to mice (IFNAR−/− or BALB/c). Artificial infection methods of ticks are important tools to study tick-virus interactions. When optimally used under laboratory settings, they provide important insights into tick-borne virus transmission cycles.

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Sequential Infection of Aedes aegypti Mosquitoes with Chikungunya Virus and Zika Virus Enhances Early Zika Virus Transmission

Insects ◽

10.3390/insects9040177 ◽

2018 ◽

Vol 9 (4) ◽

pp. 177 ◽

Cited By ~ 12

Author(s):

Tereza Magalhaes ◽

Alexis Robison ◽

Michael Young ◽

William Black ◽

Brian Foy ◽

...

Keyword(s):

Aedes Aegypti ◽

Blood Meal ◽

Zika Virus ◽

Chikungunya Virus ◽

Vector Competence ◽

Virus Transmission ◽

Mosquito Vector ◽

Molecular Aspects ◽

Virus Interactions ◽

Sequential Infection

In urban settings, chikungunya, Zika, and dengue viruses are transmitted by Aedes aegypti mosquitoes. Since these viruses co-circulate in several regions, coinfection in humans and vectors may occur, and human coinfections have been frequently reported. Yet, little is known about the molecular aspects of virus interactions within hosts and how they contribute to arbovirus transmission dynamics. We have previously shown that Aedes aegypti exposed to chikungunya and Zika viruses in the same blood meal can become coinfected and transmit both viruses simultaneously. However, mosquitoes may also become coinfected by multiple, sequential feeds on single infected hosts. Therefore, we tested whether sequential infection with chikungunya and Zika viruses impacts mosquito vector competence. We exposed Ae. aegypti mosquitoes first to one virus and 7 days later to the other virus and compared infection, dissemination, and transmission rates between sequentially and single infected groups. We found that coinfection rates were high after sequential exposure and that mosquitoes were able to co-transmit both viruses. Surprisingly, chikungunya virus coinfection enhanced Zika virus transmission 7 days after the second blood meal. Our data demonstrate heterologous arbovirus synergism within mosquitoes, by unknown mechanisms, leading to enhancement of transmission under certain conditions.

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Operational TBE incidence forecasts for Austria, Germany, and Switzerland 2019-2021

10.1101/2020.07.09.20149492 ◽

2020 ◽

Author(s):

Franz Rubel ◽

Katharina Brugger

Keyword(s):

Negative Binomial ◽

High Reliability ◽

Virus Transmission ◽

Negative Binomial Regression ◽

European Beech ◽

Transmission Cycle ◽

Tick Borne Encephalitis ◽

Tbe Virus ◽

Binomial Regression ◽

First Time

In spring 2019, forecasts of the incidence of tick-borne encephalitis (TBE) for the next two years, i.e. 2019 and 2020, were made for the first time. For this purpose, negative binomial regression models with 4-5 predictors were fitted to the time series of annual human TBE incidences from Austria, Germany and Switzerland. The most important predictor for TBE incidences is the fructification index of the European beech (Fagus sylvatica) 2 years prior as a proxi for the intensity of the TBE virus transmission cycle. These forecasts were repeated in spring 2020 after the updated predictors and the confirmed TBE cases for 2019 became available. Forecasting TBE incidences for 2020 and 2021 results in 156±19 and 131±23 TBE cases for Austria, 663±95 and 543±112 TBE cases for Germany as well as 472±56 and 350±62 TBE cases for Switzerland. The newly implemented operational TBE forecasts will be verified every year with confirmed TBE cases. An initial verification for 2019 demonstrates the high reliability of the forecasts.

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A brief history of the development of the tick-artificial feeding system

Medical Entomology and Zoology ◽

10.7601/mez.71.15 ◽

2020 ◽

Vol 71 (1) ◽

pp. 15-23

Author(s):

Takeshi Hatta

Keyword(s):

Artificial Feeding ◽

Feeding System ◽

History Of

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Host Range, Host–Virus Interactions, and Virus Transmission

Viruses ◽

10.1016/b978-0-12-811257-1.00005-x ◽

2018 ◽

pp. 101-134

Author(s):

Gustavo Fermin

Keyword(s):

Host Range ◽

Virus Transmission ◽

Host Virus Interactions ◽

Virus Interactions

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A comprehensive survey of the prevalence and spatial distribution of ticks infesting cattle in different agro-ecological zones of Cameroon

Parasites & Vectors ◽

10.1186/s13071-019-3738-7 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 8

Author(s):

Barberine A. Silatsa ◽

Gustave Simo ◽

Naftaly Githaka ◽

Stephen Mwaura ◽

Rolin M. Kamga ◽

...

Keyword(s):

Spatial Distribution ◽

Ixodid Ticks ◽

Babesia Bovis ◽

African Region ◽

Morphological Examination ◽

Additional Species ◽

Cross Sectional ◽

Morphological Criteria ◽

Cattle Ticks ◽

Tick Vectors

Abstract Background Ticks and tick-borne diseases are a major impediment to livestock production worldwide. Cattle trade and transnational transhumance create risks for the spread of ticks and tick-borne diseases and threaten cattle production in the absence of an effective tick control program. Few studies have been undertaken on cattle ticks in the Central African region; therefore, the need to assess the occurrence and the spatial distribution of tick vectors with the aim of establishing a baseline for monitoring future spread of tick borne-diseases in the region is urgent. Results A total of 7091 ixodid ticks were collected during a countrywide cross-sectional field survey and identified using morphological criteria. Of these, 4210 (59.4%) ticks were Amblyomma variegatum, 1112 (15.6%) Rhipicephalus (Boophilus) microplus, 708 (10.0%) Rhipicephalus (Boophilus) decoloratus, 28 (0.4%) Rhipicephalus (Boophilus) annulatus, 210 (3.0%) Hyalomma rufipes, 768 (10.8%) Hyalomma truncatum, and 19 (0.3%) Rhipicephalus sanguineus. Three ticks of the genus Hyalomma spp. and 33 of the genus Rhipicephalus spp. were not identified to the species level. Cytochrome c oxidase subunit 1 (cox1) gene sequencing supported the data from morphological examination and led to identification of three additional species, namely Hyalomma dromedarii, Rhipicephalus sulcatus and Rhipicephalus pusillus. The finding of the invasive tick species R. microplus in such large numbers and the apparent displacement of the indigenous R. decoloratus is highly significant since R. microplus is a highly efficient vector of Babesia bovis. Conclusions This study reports the occurrence and current geographical distribution of important tick vectors associated with cattle in Cameroon. It appears that R. microplus is now well established and may be displacing native Rhipicephalus (Boophilus) species, such as R. decoloratus. This calls for an urgent response to safeguard the livestock sector in western central Africa.

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