Wolbachia prevalence in the vector species Culex pipiens and Culex torrentium in a Sindbis virus-endemic region of Sweden

Abstract Background Wolbachia pipientis are endosymbiotic bacteria present in a large proportion of terrestrial arthropods. The species is known to sometimes affect the ability of its host to transmit vector-borne pathogens. Central Sweden is endemic for Sindbis virus (SINV), where it is mainly transmitted by the vector species Culex pipiens and Culex torrentium, with the latter established as the main vector. In this study we investigated the Wolbachia prevalence in these two vector species in a region highly endemic for SINV. Methods Culex mosquitoes were collected using CDC light traps baited with carbon dioxide over 9 years at 50 collection sites across the River Dalälven floodplains in central Sweden. Mosquito genus was determined morphologically, while a molecular method was used for reliable species determination. The presence of Wolbachia was determined through PCR using general primers targeting the wsp gene and sequencing of selected samples. Results In total, 676 Cx. pipiens and 293 Cx. torrentium were tested for Wolbachia. The prevalence of Wolbachia in Cx. pipiens was 97% (95% CI 94.8–97.6%), while only 0.7% (95% CI 0.19–2.45%) in Cx. torrentium. The two Cx. torrentium mosquitoes that were infected with Wolbachia carried different types of the bacteria. Conclusions The main vector of SINV in the investigated endemic region, Cx. torrentium, was seldom infected with Wolbachia, while it was highly prevalent in the secondary vector, Cx. pipiens. The presence of Wolbachia could potentially have an impact on the vector competence of these two species. Furthermore, the detection of Wolbachia in Cx. torrentium could indicate horizontal transmission of the endosymbiont between arthropods of different species. Graphical abstract

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Sindbis Virus Infection in Non-Blood-Fed Hibernating Culex pipiens Mosquitoes in Sweden

Viruses ◽

10.3390/v12121441 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1441

Author(s):

Alexander Bergman ◽

Emma Dahl ◽

Åke Lundkvist ◽

Jenny C. Hesson

Keyword(s):

Virus Infection ◽

Culex Pipiens ◽

Sindbis Virus ◽

Virus Transmission ◽

Blood Feeding ◽

Northern Europe ◽

Infection Status ◽

Endemic Region ◽

Viral Interactions ◽

Mosquito Ecology

A crucial, but unresolved question concerning mosquito-borne virus transmission is how these viruses can remain endemic in regions where the transmission is halted for long periods of time, due to mosquito inactivity in, e.g., winter. In northern Europe, Sindbis virus (SINV) (genus alphavirus, Togaviridae) is transmitted among birds by Culex mosquitoes during the summer, with occasional symptomatic infections occurring in humans. In winter 2018–19, we sampled hibernating Culex spp females in a SINV endemic region in Sweden and assessed them individually for SINV infection status, blood-feeding status, and species. The results showed that 35 out of the 767 collected mosquitoes were infected by SINV, i.e., an infection rate of 4.6%. The vast majority of the collected mosquitoes had not previously blood-fed (98.4%) and were of the species Cx. pipiens (99.5%). This is the first study of SINV overwintering, and it concludes that SINV can be commonly found in the hibernating Cx. pipiens population in an endemic region in Sweden, and that these mosquitoes become infected through other means besides blood-feeding. Further studies on mosquito ecology and viral interactions are needed to elucidate the mechanisms of the persistence of these viruses over winter.

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Leishmaniasis in Eurasia and Africa: geographical distribution of vector species and pathogens

Royal Society Open Science ◽

10.1098/rsos.190334 ◽

2019 ◽

Vol 6 (5) ◽

pp. 190334 ◽

Cited By ~ 2

Author(s):

Sarah Cunze ◽

Judith Kochmann ◽

Lisa K. Koch ◽

Korbinian J. Q. Hasselmann ◽

Sven Klimpel

Keyword(s):

Vector Competence ◽

Risk Assessments ◽

Neglected Diseases ◽

Vector Species ◽

Niche Modelling ◽

Northern Latitudes ◽

Suitability Maps ◽

Vector Borne ◽

Pathogen Vector ◽

Modelling Approach

Leishmaniasis is a vector-borne disease with a broad global occurrence and an increasing number of recorded cases; however, it is still one of the world's most neglected diseases. We here provide climatic suitability maps generated by means of an ecological niche modelling approach for 32 Phlebotomus vector species with proven or suspected vector competence for five Leishmania pathogens occurring in Eurasia and Africa. A GIS-based spatial overlay analysis was then used to compare the distributional patterns of vectors and pathogens to help evaluate the vector species–pathogen relationship currently found in the literature. Based on this single factor of vector incrimination, that is, co-occurrence of both vector and pathogen, most of the pathogens occurred with at least one of the associated vector species. In the case of L. donovani , only a not yet confirmed vector species, P. rodhaini, could explain the occurrence of the pathogen in regions of Africa. Phlebotomus alexandri and P. longiductus on the other hand, proven vector species of L. donovani, do not seem to qualify as vectors for the pathogen. Their distribution is restricted to northern latitudes and does not match the pathogen's distribution, which lies in southern latitudes. Other more locally confined mismatches were discussed for each pathogen species. The comparative geographical GIS-overlay of vector species and pathogens functions as a first indication that testing and re-evaluation of some pathogen–vector relationships might be worthwhile to improve risk assessments of leishmaniasis.

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The Scientific Basis for the Prevention of Zooanthroponoze Vector-Borne Diseases Spread by Parasitic Arthropods of the Center of the East European Plain

Russian Journal of Parasitology ◽

10.31016/1998-8435-2020-14-1-81-88 ◽

2020 ◽

Vol 14 (1) ◽

pp. 81-88

Author(s):

Fedor I. Vasilevich ◽

Anna M. Nikanorova

Keyword(s):

Mathematical Models ◽

Culex Pipiens ◽

Preventive Measures ◽

Mosquito Species ◽

Natural Habitat ◽

Piperonyl Butoxide ◽

East European Plain ◽

Vector Borne Diseases ◽

Vector Borne ◽

Kaluga Region

The purpose of the research is development of preventive measures against zooanthroponoze vector-borne diseases spread by parasitic arthropods in the Kaluga Region. Materials and methods. The subject of the research was Ixodidae, mosquitoes, and small mammals inhabiting the Kaluga Region. The census of parasitic arthropods was carried out on the territory of all districts of the Kaluga Region and the city of Kaluga. Open natural habitat and human settlements were investigated. Weather conditions from 2013 to 2018 were also taken into account. For the purposes of the study, we used standard methods for capturing and counting arthropods and mouse-like rodents. In order to obtain mathematical models of small mammal populations, a full factorial experiment was conducted using the collected statistical data. In-process testing of the drug based on s-fenvalerate and piperonyl butoxide were carried out under the conditions of the agricultural collective farm “Niva” of the Kozelsky District, the Kaluga Region, and LLC “Angus Center of Genetics” of the Babyninsky District, the Kaluga Region. Results and discussion. In the Kaluga Region, two species of ixodic ticks are found, namely, Ixodes ricinus and Dermacentor reticulatus, which have two activity peaks. Mosquito may have 3-4 generations in a year in the Kaluga region. The most common mosquito species in the Kaluga Region are Aedes communis, Ae. (Och.) togoi and Ae. (Och.) diantaeus, Culex pipiens Culex Linnaeus, 1758 (Diptera, Culicidae) (Culex pipiens): Cx. pipiens f. pipiens L. (non-autogenic form) and Cx. p. f. molestus Fors. (autogenic form), which interbreed, and reproductively isolated in the Region. The developed mathematical models make it possible to quantify the risks of outbreaks of zooanthroponoze vector-borne diseases without the cost of field research, and allow for rational, timely and effective preventive measures. Medications based on s-fenvalerate and piperonyl butoxide and based on cyfluthrin showed high insecto-acaricidal efficacy and safety.

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B19 Vector competence of mosquitoes against arboviruses (5) : Susceptibility of West Nile virus-infected Culex pipiens pallens, Culex pipiens molestus and Aedes albopictus exposed to different temperatures

Medical Entomology and Zoology ◽

10.7601/mez.54.42_1 ◽

2003 ◽

Vol 54 (supplement) ◽

pp. 42

Author(s):

Y. Eshita ◽

S. Anzai ◽

T. Takasaki ◽

K. Yamada ◽

Y. Uchida ◽

...

Keyword(s):

West Nile Virus ◽

Aedes Albopictus ◽

Culex Pipiens ◽

Vector Competence ◽

Culex Pipiens Pallens ◽

West Nile ◽

Different Temperatures ◽

Culex Pipiens Molestus ◽

Pipiens Pallens

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Environmental and Biological Factors Influencing Culex pipiens quinquefasciatus (Diptera: Culicidae) Vector Competence for West Nile Virus

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.2010.09-0776 ◽

2010 ◽

Vol 83 (1) ◽

pp. 126-134 ◽

Cited By ~ 28

Author(s):

Stephanie L. Richards ◽

Cynthia C. Lord ◽

Kendra N. Pesko ◽

Walter J. Tabachnick

Keyword(s):

West Nile Virus ◽

Culex Pipiens ◽

Vector Competence ◽

Biological Factors ◽

West Nile ◽

Culex Pipiens Quinquefasciatus ◽

Factors Influencing

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Understanding the effect of temperature on Bluetongue disease risk in livestock

10.1101/759860 ◽

2019 ◽

Cited By ~ 1

Author(s):

Fadoua El Moustaid ◽

Zorian Thronton ◽

Hani Slamani ◽

Sadie J. Ryan ◽

Leah R. Johnson

Keyword(s):

Disease Risk ◽

Vector Competence ◽

Basic Reproductive Number ◽

Effect Of Temperature ◽

Reproductive Number ◽

Temperature Sensitive ◽

Modeling Tools ◽

Vector Borne Diseases ◽

Thermal Range ◽

Vector Borne

AbstractThe transmission of vector-borne diseases is governed by complex factors including pathogen characteristics, vector-host interactions, and environmental conditions. Temperature is a major driver for many vector-borne diseases including Bluetongue viral (BTV) disease, a midge-borne febrile disease of ruminants, notably livestock, whose etiology ranges from mild or asymptomatic to rapidly fatal, thus threatening animal agriculture and the economy of affected countries. Using modeling tools, we seek to predict where transmission can occur based on suitable temperatures for BTV. We fit thermal performance curves to temperature sensitive midge life history traits, using a Bayesian approach. Then, we incorporated these into a new formula for the disease basic reproductive number, R0, to include trait responses, for two species of key midge vectors, Culicoides sonorensis and Culicoides variipennis. Our results show that outbreaks of BTV are more likely between 15°C and 33°C with predicted peak transmission at 26°C. The greatest uncertainty in R0 is associated with the uncertainty in: mortality and fecundity of midges near optimal temperature for transmission; midges’ probability of becoming infectious post infection at the lower edge of the thermal range; and the biting rate together with vector competence at the higher edge of the thermal range. We compare our R0 to two other R0 formulations and show that incorporating thermal curves into all three leads to similar BTV risk predictions. To demonstrate the utility of this model approach, we created global suitability maps indicating the areas at high and long-term risk of BTV transmission, to assess risk, and anticipate potential locations of establishment.

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Vector competence is strongly affected by a small deletion or point mutations in bluetongue virus

Parasites & Vectors ◽

10.1186/s13071-019-3722-2 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 6

Author(s):

René G. P. van Gennip ◽

Barbara S. Drolet ◽

Paula Rozo Lopez ◽

Ashley J. C. Roost ◽

Jan Boonstra ◽

...

Keyword(s):

Virus Replication ◽

Bluetongue Virus ◽

Vector Competence ◽

Outer Shell ◽

Virus Propagation ◽

Virus Growth ◽

Shell Protein ◽

Vector Borne

Abstract Background Transmission of vector-borne virus by insects is a complex mechanism consisting of many different processes; viremia in the host, uptake, infection and dissemination in the vector, and delivery of virus during blood-feeding leading to infection of the susceptible host. Bluetongue virus (BTV) is the prototype vector-borne orbivirus (family Reoviridae). BTV serotypes 1–24 (typical BTVs) are transmitted by competent biting Culicoides midges and replicate in mammalian (BSR) and midge (KC) cells. Previously, we showed that genome segment 10 (S10) encoding NS3/NS3a protein is required for virus propagation in midges. BTV serotypes 25–27 (atypical BTVs) do not replicate in KC cells. Several distinct BTV26 genome segments cause this so-called ‘differential virus replication’ in vitro. Methods Virus strains were generated using reverse genetics and their growth was examined in vitro. The midge feeding model has been developed to study infection, replication and disseminations of virus in vivo. A laboratory colony of C. sonorensis, a known competent BTV vector, was fed or injected with BTV variants and propagation in the midge was examined using PCR testing. Crossing of the midgut infection barrier was examined by separate testing of midge heads and bodies. Results A 100 nl blood meal containing ±105.3 TCID50/ml of BTV11 which corresponds to ±20 TCID50 infected 50% of fully engorged midges, and is named one Midge Alimentary Infective Dose (MAID50). BTV11 with a small in-frame deletion in S10 infected blood-fed midge midguts but virus release from the midgut into the haemolymph was blocked. BTV11 with S1[VP1] of BTV26 could be adapted to virus growth in KC cells, and contained mutations subdivided into ‘corrections’ of the chimeric genome constellation and mutations associated with adaptation to KC cells. In particular one amino acid mutation in outer shell protein VP2 overcomes differential virus replication in vitro and in vivo. Conclusion Small changes in NS3/NS3a or in the outer shell protein VP2 strongly affect virus propagation in midges and thus vector competence. Therefore, spread of disease by competent Culicoides midges can strongly differ for very closely related viruses.

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Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks

Viruses ◽

10.3390/v11100941 ◽

2019 ◽

Vol 11 (10) ◽

pp. 941 ◽

Cited By ~ 7

Author(s):

Valentina Federici ◽

Maria Goffredo ◽

Giuseppe Mancini ◽

Michela Quaglia ◽

Adriana Santilli ◽

...

Keyword(s):

Bluetongue Virus ◽

Vector Competence ◽

Oral Infection ◽

Balearic Islands ◽

Rt Pcr ◽

Vector Species ◽

Vaccination Programs ◽

Culicoides Obsoletus ◽

Culicoides Imicola ◽

Virus Strains

The distribution of Bluetongue virus (BTV) in Europe can be represented by two distinct and interconnected epidemiological systems (episystems), each characterized by different ecological characteristics and vector species. This study investigated the vector competence of Italian populations of Culicoides imicola and Culicoides obsoletus/scoticus to some representative BTV strains after artificial oral infection. The BTV strains were selected according to their ability to spread to one or both episystems and included BTV-4 ITA, responsible of the recent Italian and French BTV-4 outbreaks; the BTV-2 strain which caused the first BTV incursion in Italy, Corsica, and Balearic Islands; BTV-4 MOR, responsible for the epidemic in Morocco; and BTV-8, the strain which spread through Europe between 2006 and 2008. Blood-soaked cotton pledgets and Hemotek membrane feeder using Parafilm® membrane were used to artificially feed midges. For each population/strain, recovery rates (positive/tested heads) were evaluated using serogroup- and serotype-specific RT-PCR. The trial demonstrated that, except for the Abruzzo population of C. obsoletus/C. scoticus, which was refractory to BTV-4 MOR infection, all the investigated Culicoides populations are susceptible to the selected BTV strains and that, if prompt vaccination programs and restriction measures had not been implemented, BTV-2 and BTV-4 MOR could have spread all over Europe.

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