#Vector #competence of biting #midges and #mosquitoes for #Shuni virus (PLoS Negl Trop Dis., abstract)

[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Vector competence of biting midges and mosquitoes for Shuni virus

Tim W. R. Möhlmann , Judith Oymans, Paul J. Wichgers Schreur, Constantianus J. M. Koenraadt, Jeroen Kortekaas, Chantal B. F. Vogels

Published: February 12, 2019 / DOI: https://doi.org/10.1371/journal.pntd.0006609

 

Abstract

Background

Shuni virus (SHUV) is an orthobunyavirus that belongs to the Simbu serogroup. SHUV was isolated from diverse species of domesticated animals and wildlife, and is associated with neurological disease, abortions, and congenital malformations. Recently, SHUV caused outbreaks among ruminants in Israel, representing the first incursions outside the African continent. The isolation of SHUV from a febrile child in Nigeria and seroprevalence among veterinarians in South Africa suggests that the virus may have zoonotic potential as well. The high pathogenicity, extremely broad tropism, potential transmission via both biting midges and mosquitoes, and zoonotic features of SHUV require further investigation. This is important to accurately determine the risk for animal and human health, and to facilitate preparations for potential epidemics. To gain first insight into the potential involvement of biting midges and mosquitoes in SHUV transmission we have investigated the ability of SHUV to infect two species of laboratory-colonised biting midges and two species of mosquitoes.

Methodology/Principal findings

Culicoides nubeculosus, C. sonorensis, Culex pipiens pipiens, and Aedes aegypti were orally exposed to SHUV by providing an infectious blood meal. Biting midges showed high infection rates of approximately 40%-60%, whereas infection rates of mosquitoes were only 0–2%. Moreover, successful dissemination in both species of biting midges and no evidence for transmission by orally exposed mosquitoes was found.

Conclusions/Significance

The results of this study suggest that different species of Culicoides midges are efficient in SHUV transmission, while the involvement of mosquitoes has not been supported.

 

Author summary

Arthropod-borne (arbo)viruses are notorious for causing unpredictable and large-scale epidemics and epizootics. Apart from viruses such as West Nile virus and Rift Valley fever virus that are well-known to cause a significant impact on human and animal health, many arboviruses remain neglected. Shuni virus (SHUV) is a neglected virus with zoonotic characteristics that was recently associated with severe disease in livestock and wildlife. Isolations from field-collected biting midges and mosquitoes suggests that SHUV may be transmitted by these insects. In this study, four main vectors that transmit other arboviruses were selected to test their susceptibility to SHUV. Laboratory-reared biting midge species (Culicoides nubeculosus and C. sonorensis) and mosquito species (Culex pipiens pipiens and Aedes aegypti) were exposed to SHUV via an infectious blood meal. SHUV was able to successfully disseminate in both biting midge species, whereas no evidence of transmission by both mosquito species was found. Our results suggest that SHUV can be transmitted efficiently by diverse Culicoides species, and thereby that these insects could play a major role in the disease transmission cycle.

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Citation: Möhlmann TWR, Oymans J, Wichgers Schreur PJ, Koenraadt CJM, Kortekaas J, Vogels CBF (2019) Vector competence of biting midges and mosquitoes for Shuni virus. PLoS Negl Trop Dis 13(2): e0006609. https://doi.org/10.1371/journal.pntd.0006609

Editor: David Harley, University of Queensland, AUSTRALIA

Received: May 31, 2018; Accepted: June 13, 2018; Published: February 12, 2019

Copyright: © 2019 Möhlmann et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the paper

Funding: TWRM, CJMK, and CBFV received funding from the Global One Health strategic programme of Wageningen University and Research, and JO, PJWS, and JK received funding from the Dutch Ministry of Agriculture, Nature and Food Quality; project WOT-01-001-033. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Orthobunyavirus; Shuni virus; Arbovirus; Mosquitoes; Midges.

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Engineered #resistance to #Zika virus in transgenic #Aedes aegypti expressing a polycistronic cluster of synthetic small RNAs (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Engineered resistance to Zika virus in transgenic Aedes aegypti expressing a polycistronic cluster of synthetic small RNAs

Anna Buchman, Stephanie Gamez, Ming Li, Igor Antoshechkin, Hsing-Han Li, Hsin-Wei Wang, Chun-Hong Chen, Melissa J. Klein, Jean-Bernard Duchemin, Prasad N. Paradkar, and Omar S. Akbari

PNAS published ahead of print February 5, 2019 / DOI: https://doi.org/10.1073/pnas.1810771116

Edited by Alexander S. Raikhel, University of California, Riverside, CA, and approved December 31, 2018 (received for review June 22, 2018)

 

Significance

Here, we describe the generation of Aedes aegypti mosquitoes that are engineered to be resistant to Zika virus (ZIKV) transmission. Our results demonstrate that engineered mosquitoes express a polycistronic cluster of synthetic small RNAs designed to target the ZIKV genome. As a result, homozygous mosquitoes were refractory to ZIKV infection, and therefore could not transmit the virus. Additionally, mosquitoes heterozygous for the transgene showed significantly lower levels of viral infection, dissemination, and transmission compared with wild-type mosquitoes; importantly, these levels were low enough to make such mosquitoes unlikely to transmit ZIKV to a susceptible host. Finally, we discuss how such an engineering approach can be used to combat the major health burden of ZIKV, and potentially other arboviruses, in the future.

 

Abstract

Recent Zika virus (ZIKV) outbreaks have highlighted the necessity for development of novel vector control strategies to combat arboviral transmission, including genetic versions of the sterile insect technique, artificial infection with Wolbachia to reduce population size and/or vectoring competency, and gene drive-based methods. Here, we describe the development of mosquitoes synthetically engineered to impede vector competence to ZIKV. We demonstrate that a polycistronic cluster of engineered synthetic small RNAs targeting ZIKV is expressed and fully processed in Aedes aegypti, ensuring the formation of mature synthetic small RNAs in the midgut where ZIKV resides in the early stages of infection. Critically, we demonstrate that engineered Ae. aegypti mosquitoes harboring the anti-ZIKV transgene have significantly reduced viral infection, dissemination, and transmission rates of ZIKV. Taken together, these compelling results provide a promising path forward for development of effective genetic-based ZIKV control strategies, which could potentially be extended to curtail other arboviruses.

ZIKA – resistance – Aedes aegypti – mosquito

Keywords: Zika Virus; Mosquitoes; Aedes aegypti; Genetics.

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#Arbovirus #coinfection and co-transmission: A neglected #publichealth concern? (PLoS Biol., abstract)

[Source: PLoS Biology, full page: (LINK). Abstract, edited.]

OPEN ACCESS / UNSOLVED MYSTERY

Arbovirus coinfection and co-transmission: A neglected public health concern?

Chantal B. F. Vogels , Claudia Rückert , Sean M. Cavany , T. Alex Perkins, Gregory D. Ebel, Nathan D. Grubaugh

Published: January 22, 2019 / DOI: https://doi.org/10.1371/journal.pbio.3000130 / This is an uncorrected proof.

 

Abstract

Epidemiological synergy between outbreaks of viruses transmitted by Aedes aegypti mosquitoes, such as chikungunya, dengue, and Zika viruses, has resulted in coinfection of humans with multiple viruses. Despite the potential impact on public health, we know only little about the occurrence and consequences of such coinfections. Here, we review the impact of coinfection on clinical disease in humans, discuss the possibility for co-transmission from mosquito to human, and describe a role for modeling transmission dynamics at various levels of co-transmission. Solving the mystery of virus coinfections will reveal whether they should be viewed as a serious concern for public health.

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Citation: Vogels CBF, Rückert C, Cavany SM, Perkins TA, Ebel GD, Grubaugh ND (2019) Arbovirus coinfection and co-transmission: A neglected public health concern? PLoS Biol 17(1): e3000130. https://doi.org/10.1371/journal.pbio.3000130

Published: January 22, 2019

Copyright: © 2019 Vogels et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: CBFV is supported by NWO Rubicon 019.181EN.004, CR and GDE are supported by NIH NIAID AI067380, SMC and TAP are supported by NIH NIAID 1P01AI098670, and TAP is supported by DARPA D16AP00114. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Abbreviations: CHIKV, chikungunya virus; DENV, dengue virus; NS1, nonstructural protein 1; STAT1, signal transducer and activator of transcription 1; STAT2, signal transducer and activator of transcription 2; XRN1, 5′-3′ exoribonuclease 1; ZIKV, Zika virus

Keywords: Arbovirus; Zika Virus; Chikungunya fever; Mosquitoes; Aedes aegypti.

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#Insecticide #resistance genes affect #Culex quinquefasciatus #vector competence for #WNV (Proc Roy Soc B., abstract)

[Source: Proceedings of the Royal Society Biological Sciences, full page: (LINK). Abstract, edited.]

Insecticide resistance genes affect Culex quinquefasciatus vector competence for West Nile virus

Célestine M. Atyame, Haoues Alout, Laurence Mousson, Marie Vazeille, Mawlouth Diallo, Mylène Weill and Anna-Bella Failloux

Published: 16 January 2019 / DOI: https://doi.org/10.1098/rspb.2018.2273

 

Abstract

Insecticide resistance has been reported to impact the interactions between mosquitoes and the pathogens they transmit. However, the effect on vector competence for arboviruses still remained to be investigated. We examined the influence of two insecticide resistance mechanisms on vector competence of the mosquito Culex quinquefasciatus for two arboviruses, Rift Valley Fever virus (RVFV) and West Nile virus (WNV). Three Cx. quinquefasciatus lines sharing a common genetic background were used: two insecticide-resistant lines, one homozygous for amplification of the Ester2locus (SA2), the other homozygous for the acetylcholinesterase ace-1 G119S mutation (SR) and the insecticide-susceptible reference line Slab. Statistical analyses revealed no significant effect of insecticide-resistant mechanisms on vector competence for RVFV. However, both insecticide resistance mechanisms significantly influenced the outcome of WNV infections by increasing the dissemination of WNV in the mosquito body, therefore leading to an increase in transmission efficiency by resistant mosquitoes. These results showed that insecticide resistance mechanisms enhanced vector competence for WNV and may have a significant impact on transmission dynamics of arboviruses. Our findings highlight the importance of understanding the impacts of insecticide resistance on the vectorial capacity parameters to assess the overall consequence on transmission.

Keywords: Arbovirus; Rift Valley Fever virus; West Nile Virus; Mosquitoes; Insecticides; Culex quinquefasciatus.

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New #strains of Japanese #encephalitis virus circulating in #Shanghai, #China after a ten-year hiatus in local #mosquito #surveillance (Parasit Vectors, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Parasit Vectors. 2019 Jan 9;12(1):22. doi: 10.1186/s13071-018-3267-9.

New strains of Japanese encephalitis virus circulating in Shanghai, China after a ten-year hiatus in local mosquito surveillance.

Fang Y1, Zhang Y2, Zhou ZB1, Xia S1, Shi WQ1, Xue JB1, Li YY1, Wu JT1.

Author information: 1 National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, 20025, People’s Republic of China. 2 National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, 20025, People’s Republic of China. zhang1972003@163.com.

 

Abstract

BACKGROUND:

Continuous vector pathogen surveillance is essential for preventing outbreaks of mosquito-borne diseases. Several mosquito species acting as vectors of Japanese encephalitis virus (JEV), dengue virus, Zika virus, malaria parasites and other pathogens are primary mosquito species in Shanghai, China. However, few surveys of human pathogenic arboviruses in mosquitoes in Shanghai have been reported in the last ten years. Therefore, in this study, we evaluated mosquito activity in Shanghai, China during 2016 and tested for the presence of alphaviruses, flaviviruses, orthobunyaviruses and several parasitic pathogens.

RESULTS:

Five pooled samples were JEV-positive [4/255 pools of Culex tritaeniorhynchus and 1/256 pools of Cx. pipiens (s.l.)] based on analysis of the NS5 gene. Alphaviruses, orthobunyaviruses, Plasmodium and filariasis were not found in this study. Phylogenetic and molecular analyses revealed that the JEV strains belonged to genotype I. Moreover, newly detected Shanghai JEV strains were genetically close to previously isolated Shandong strains responsible for transmission during the 2013 Japanese encephalitis (JE) outbreak in Shandong Province, China but were more distantly related to other Shanghai strains detected in the early 2000s. The E proteins of the newly detected Shanghai JEV strains differed from that in the live attenuated vaccine SA14-14-2-derived strain at six amino residues: E130 (Ile→Val), E222 (Ala→Ser), E327 (Ser→Thr), E366 (Arg→Ser/Pro), E393 (Asn→Ser) and E433 (Val→Ile). However, no differences were observed in key amino acid sites related to antigenicity. Minimum JEV infection rates were 1.01 and 0.65 per 1000 Cx. tritaeniorhynchus and Cx. pipiens (s.l.), respectively.

CONCLUSIONS:

Five new Shanghai JEV genotype I strains, detected after a ten-year hiatus in local mosquito surveillance, were genetically close to strains involved in the 2013 Shandong JE outbreak. Because JEV is still circulating, vaccination in children should be extensively and continuously promoted. Moreover, JEV mosquito surveillance programmes should document the genotype variation, intensity and distribution of circulating viruses for use in the development and implementation of disease prevention and control strategies.

KEYWORDS: Culex pipiens; Culex tritaeniorhynchus; Japanese encephalitis; Mosquito-borne diseases; SA14-14-2

PMID: 30626442 DOI: 10.1186/s13071-018-3267-9

Keywords: Japanese Encephalitis; Arbovirus; Mosquitoes; China; Shanghai; Culex spp.

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Influence of #Demography, #Land Use, and #Urban Form on #WNV #Risk and #Human West Nile Virus Incidence in #Ottawa, #Canada (Vector Borne Zoo Dis., abstract)

[Source: Vector Borne and Zoonotic Diseases, full page: (LINK). Abstract, edited.]

Influence of Demography, Land Use, and Urban Form on West Nile Virus Risk and Human West Nile Virus Incidence in Ottawa, Canada

Benoit Talbot, Mark Ardis, and Manisha A. Kulkarni

Published Online: 7 Jan 2019 / DOI: https://doi.org/10.1089/vbz.2018.2366

 

Abstract

Human infection by West Nile virus (WNV; family Flaviviridae), in some cases, develops into a deadly neuroinvasive disease. WNV risk is thought to be influenced by factors affecting the density of species that promote replication and transmission of the virus, namely peridomestic bird and mosquito species. Factors influencing contact between peridomestic bird and mosquito species and contact between infected mosquitoes and vulnerable human populations may also be important in determining WNV risk in an area. Several urban form and demographic factors, such as population density and the proportion of aged housing units, have been linked with increased WNV risk. Other factors, such as proportion of old-growth forest and wetlands, have been linked to decreased WNV risk. In this study, we aimed to test the effect of several demographic, land use, and urban form variables on WNV risk within neighborhoods of the city of Ottawa, Canada, based on the spatiotemporal clustering of infected mosquitoes and human WNV cases. We found a large positive effect of population density and proportion of aged housing units on WNV risk, using both entomological and epidemiological data. Interestingly, we found a large negative effect of proportion of natural areas in our epidemiological analysis, but not in our entomological analysis. Although our epidemiological data set was relatively small, these results suggest entomological surveillance results should be interpreted alongside other factors when investigating risk to humans. Our study is also one of the few to suggest an effect of demography, land use, and urban form on WNV risk in a Canadian urban center, using both entomological and epidemiological data.

Keywords: WNV; Canada; Society; Mosquitoes.

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#Mapping the #global potential #distributions of two #arboviral vectors #Aedes aegypti and Ae. albopictus under changing #climate (PLoS One, abstract)

[Source: PLoS One, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Mapping the global potential distributions of two arboviral vectors Aedes aegypti and Ae. albopictus under changing climate

Mahmoud Kamal , Mohamed A. Kenawy, Magda Hassan Rady, Amany Soliman Khaled, Abdallah M. Samy

Published: December 31, 2018 / DOI: https://doi.org/10.1371/journal.pone.0210122

 

Abstract

Background

Aedes aegypti and Ae. albopictus are the primary vectors that transmit several arboviral diseases, including dengue, chikungunya, and Zika. The world is presently experiencing a series of outbreaks of these diseases, so, we still require to better understand the current distributions and possible future shifts of their vectors for successful surveillance and control programs. Few studies assessed the influences of climate change on the spatial distributional patterns and abundance of these important vectors, particularly using the most recent climatic scenarios. Here, we updated the current potential distributions of both vectors and assessed their distributional changes under future climate conditions.

Methods

We used ecological niche modeling approach to estimate the potential distributions of Ae. aegypti and Ae. albopictus under present-day and future climate conditions. This approach fits ecological niche model from occurrence records of each species and environmental variables. For each species, future projections were based on climatic data from 9 general circulation models (GCMs) for each representative concentration pathway (RCP) in each time period, with a total of 72 combinations in four RCPs in 2050 and 2070. All ENMs were tested using the partial receiver operating characteristic (pROC) and a set of 2,048 and 2,003 additional independent records for Ae. aegypti and Ae. albopictus, respectively. Finally, we used background similarity test to assess the similarity between the ENMs of Ae. aegypti and Ae. albopictus.

Results

The predicted potential distribution of Ae. aegypti and Ae. albopictus coincided with the current and historical known distributions of both species. Aedes aegypti showed a markedly broader distributional potential across tropical and subtropical regions than Ae. albopictus. Interestingly, Ae. albopictus was markedly broader in distributional potential across temperate Europe and the United States. All ecological niche models (ENMs) were statistically robust (P < 0.001). ENMs successfully anticipated 98% (1,999/2,048) and 99% (1,985/2,003) of additional independent records for both Ae. aegypti and Ae. albopictus, respectively (P < 0.001). ENMs based on future conditions showed similarity between the overall distributional patterns of future-day and present-day conditions; however, there was a northern range expansion in the continental USA to include parts of Southern Canada in case of Ae. albopictus in both 2050 and 2070. Future models also anticipated further expansion of Ae. albopictus to the East to include most of Europe in both time periods. Aedes aegypti was anticipated to expand to the South in East Australia in 2050 and 2070. The predictions showed differences in distributional potential of both species between diverse RCPs in 2050 and 2070. Finally, the background similarity test comparing the ENMs of Ae. aegypti and Ae. albopictus was unable to reject the null hypothesis of niche similarity between both species (P > 0.05).

Conclusion

These updated maps provided details to better guide surveillance and control programs of Ae. aegypti and Ae. albopictus. They have also significant public health importance as a baseline for predicting the emergence of arboviral diseases transmitted by both vectors in new areas across the world.

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Citation: Kamal M, Kenawy MA, Rady MH, Khaled AS, Samy AM (2018) Mapping the global potential distributions of two arboviral vectors Aedes aegypti and Ae. albopictusunder changing climate. PLoS ONE 13(12): e0210122. https://doi.org/10.1371/journal.pone.0210122

Editor: Nagila Francinete Costa Secundino, Instituto de Pesquisas de Rene Rachou, BRAZIL

Received: September 21, 2018; Accepted: December 17, 2018; Published: December 31, 2018

Copyright: © 2018 Kamal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files. GeoTIFF dataset for different general circulation models are openly available via Figshare repository, https://figshare.com/s/6b18c6ce273a3ecaaddc.

Funding: The authors received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Arbovirus; Mosquitoes; Worldwide; Clima change; Aedes aegypti; Aedes albopictus.

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