#Sequential #Infection of #Aedes aegypti #Mosquitoes with #Chikungunya Virus and #Zika Virus Enhances Early Zika Virus Transmission (Insects, abstract)

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

Insects. 2018 Dec 1;9(4). pii: E177. doi: 10.3390/insects9040177.

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

Magalhaes T1, Robison A2, Young MC3, Black WC 4th4, Foy BD5, Ebel GD6, Rückert C7.

Author information: 1 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. Tereza.Magalhaes@colostate.edu. 2 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. lexir5394@gmail.com. 3 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. emceeyoung@gmail.com. 4 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. William.Black@colostate.edu. 5 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. Brian.Foy@colostate.edu. 6 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. Gregory.Ebel@colostate.edu. 7 Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA. Claudia.Rueckert@Colostate.edu.

 

Abstract

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.

KEYWORDS: Zika; arboviruses; chikungunya; coinfection; mosquitoes; sequential infection

PMID: 30513725 DOI: 10.3390/insects9040177

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

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Conserved motifs in the hypervariable domain of #chikungunya virus nsP3 required for #transmission by #Aedes aegypti #mosquitoes (PLoS Negl Trop Dis., abstract)

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

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Conserved motifs in the hypervariable domain of chikungunya virus nsP3 required for transmission by Aedes aegypti mosquitoes

Giel P. Göertz, Marit Lingemann, Corinne Geertsema, Marleen H. C. Abma-Henkens, Chantal B. F. Vogels, Constantianus J. M. Koenraadt, Monique M. van Oers, Gorben P. Pijlman

Published: November 9, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006958 / This is an uncorrected proof.

 

Abstract

Background

Chikungunya virus (CHIKV) is a re-emerging arthropod-borne (arbo)virus that causes chikungunya fever in humans and is predominantly transmitted by Aedes aegypti mosquitoes. The CHIKV replication machinery consists of four non-structural proteins (nsP1-4) that additionally require the presence of a number of host proteins for replication of the viral RNA. NsP3 is essential for CHIKV replication and has a conserved macro, central and C-terminal hypervariable domain (HVD). The HVD is intrinsically disordered and interacts with various host proteins via conserved short peptide motifs: A proline-rich (P-rich) motif that has affinity for SH3-domain containing proteins and duplicate FGDF motifs with affinity for G3BP and its mosquito homologue Rasputin. The importance of these motifs for infection of mammalian cells has previously been implicated. However, their role during CHIKV infection of mosquito cells and transmission by mosquitoes remains unclear.

Methodology / Principal findings

Here, we show that in-frame deletion of the P-rich motif is lethal for CHIKV replication in both mosquito and mammalian cells. However, while mutagenesis of the P-rich motif negatively affects replication both in mammalian and mosquito cells, it did not compromise the infection and transmission of CHIKV by Ae. aegypti mosquitoes. Mutagenesis of both FGDF motifs together completely inactivated CHIKV replication in both mammalian and mosquito cells. Importantly, mutation of a single FGDF motif attenuated CHIKV replication in mammalian cells, while replication in mosquito cells was similar to wild type. Surprisingly, CHIKV mutants containing only a single FGDF motif were efficiently transmitted by Ae. aegypti.

Conclusions / Significance

The P-rich motif in CHIKV nsP3 is dispensable for transmission by mosquitoes. A single FGDF motif is sufficient for infection and dissemination in mosquitoes, but duplicate FGDF motifs are required for the efficient infection from the mosquito saliva to a vertebrate host. These results contribute to understanding the dynamics of the alphavirus transmission cycle and may help the development of arboviral intervention strategies.

 

Author summary

Chikungunya virus (CHIKV) is a re-emerging arthropod-borne virus that is transmitted predominantly by Aedes aegypti mosquitoes. In 2016 alone CHIKV caused over 100.000 infections in South-America, exemplifying the impact of CHIKV disease. Previous research has suggested that the CHIKV non-structural protein 3 (nsP3) may determine the infection of mosquitoes. NsP3 is known to interact with several host proteins through a conserved proline (P)-rich and duplicate FGDF motifs that are present in its C-terminal domain. Here we investigated the importance of these conserved motifs for the infection and replication of CHIKV in both Aedes mosquito cells and mammalian cells. Furthermore, we assessed the role of these motifs for the transmission by Ae. aegypti mosquitoes via infectious bloodmeal experiments. We show that mutation of the P-rich motif negatively affects the replication of CHIKV in both mammalian and mosquito cells. In contrast, mutating the P-rich motif did not affect the transmission by Ae. aegypti. Mutation of both FGDF motifs together completely inactivated CHIKV in mammalian and mosquito cells, while mutation of a single FGDF motif negatively affected replication only in mammalian cells. Importantly, CHIKV containing only a single FGDF motif was still efficiently transmitted by Ae. aegypti mosquitoes. These results contribute to understanding the key interactions between alphaviruses and their mosquito vector.

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Citation: Göertz GP, Lingemann M, Geertsema C, Abma-Henkens MHC, Vogels CBF, Koenraadt CJM, et al. (2018) Conserved motifs in the hypervariable domain of chikungunya virus nsP3 required for transmission by Aedes aegypti mosquitoes. PLoS Negl Trop Dis 12(11): e0006958. https://doi.org/10.1371/journal.pntd.0006958

Editor: Lyric C. Bartholomay, University of Wisconsin Madison, UNITED STATES

Received: August 3, 2018; Accepted: October 29, 2018; Published: November 9, 2018

Copyright: © 2018 Göertz 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 and its Supporting Information files.

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

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

Keywords: Chikungunya Fever; Mosquitoes; Aedes aegypti.

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Study of #Aedes aegypti #population with emphasis on the #gonotrophic cycle length and identification of #arboviruses: implications for vector #management in #cemeteries (Rev Inst Med Trop Sao Paulo, abstract)

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

Rev Inst Med Trop Sao Paulo. 2018 Aug 20;60:e44. doi: 10.1590/S1678-9946201860044.

Study of Aedes aegypti population with emphasis on the gonotrophic cycle length and identification of arboviruses: implications for vector management in cemeteries.

Garcia-Rejon JE1, Ulloa-Garcia A2, Cigarroa-Toledo N1, Pech-May A3, Machain-Williams C1, Cetina-Trejo RC1, Talavera-Aguilar LG1, Torres-Chable OM4, Navarro JC5, Baak-Baak CM1.

Author information: 1 Universidad Autonoma de Yucatan, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Laboratorio de Arbovirologia, Merida, Yucatan, Mexico. 2 Instituto Nacional de Salud Publica, Centro Regional de Investigación en Salud Publica, Tapachula, Chiapas, Mexico. 3 Instituto Nacional de Medicina Tropical, Puerto Iguazú, Misiones, Argentina. 4 Universidad Juarez Autonoma de Tabasco, Laboratorio de Enfermedades Tropicales y Transmitidas por Vector, Tabasco, Mexico. 5 Universidad Internacional SEK, Facultad de Ciencias Naturales y Ambientales, Laboratorio de Biodiversidad y Salud Ambiental, Quito, Ecuador.

 

Abstract

Aedes aegypti is the vector of the arboviruses causing dengue, chikungunya and zika infections in Mexico. However, its presence in public places has not been fully evaluated. In a cemetery from Merida, Yucatan, Mexico, the productivity of Ae. aegypti, the gonotrophic cycle, and the presence of Ae. aegypti females infected with arboviruses were evaluated. Immature and adult mosquitoes were inspected every two months between April 2016 to June 2017. For the gonotrophic cycle length, the daily pattern of total and parous female ratio was registered and was analyzed using time series analysis. Ae. aegypti females were sorted into pools and assayed for flavivirus RNA by RT-PCR and Sanger sequencing. Aedes aegypti immatures represented 82.86% (8,627/10,411) of the collection. In total, 1,648 Ae. aegypti females were sorted into 166 pools. Two pools were positive; one for dengue virus (DENV-1) and the other for zika virus (ZIKV). The phylogenetic analysis revealed that the DENV-1 is more closely related to isolates from Brazil. While ZIKV is more closely related to the Asian lineage, which were isolates from Guatemala and Mexico. We report some evidence of vertical transmission of DENV-1 in nulliparous females of Ae. aegypti. The gonotrophic cycle was four and three days in the rainy and dry season, respectively. The cemetery of Merida is an important focus of Ae. aegypti proliferation, and these environments may play a role in arboviruses transmission; probably limiting the efficacy of attempts to suppress the presence of mosquitoes in domestic environments.

PMID: 30133604 DOI: 10.1590/S1678-9946201860044

Keywords: Arbovirus; Aedes aegypti; Mosquitoes; Zika Virus; Dengue Fever; Brazil.

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Estimating the effects of #variation in #viremia on #mosquito susceptibility, infectiousness, and #R0 of #Zika in #Aedes aegypti (PLoS Negl Trop Dis., abstract)

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

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Estimating the effects of variation in viremia on mosquito susceptibility, infectiousness, and R0 of Zika in Aedes aegypti

Blanka Tesla , Leah R. Demakovsky, Hannah S. Packiam, Erin A. Mordecai, Américo D. Rodríguez, Matthew H. Bonds, Melinda A. Brindley, Courtney C. Murdock

Published: August 22, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006733 / This is an uncorrected proof.

 

Abstract

Zika virus (ZIKV) is an arbovirus primarily transmitted by Aedes mosquitoes. Like most viral infections, ZIKV viremia varies over several orders of magnitude, with unknown consequences for transmission. To determine the effect of viral concentration on ZIKV transmission risk, we exposed field-derived Ae. aegypti mosquitoes to four doses (103, 104, 105, 106 PFU/mL) representative of potential variation in the field. We demonstrate that increasing ZIKV dose in the blood-meal significantly increases the probability of mosquitoes becoming infected, and consequently disseminating virus and becoming infectious. Additionally, we observed significant interactions between dose and days post-infection on dissemination and overall transmission efficiency, suggesting that variation in ZIKV dose affects the rates of midgut escape and salivary gland invasion. We did not find significant effects of dose on mosquito mortality. We also demonstrate that detecting virus using RT-qPCR approaches rather than plaque assays potentially over-estimates key transmission parameters, including the time at which mosquitoes become infectious and viral burden. Finally, using these data to parameterize an R0 model, we showed that increasing viremia from 104 to 106 PFU/mL increased relative R0 3.8-fold, demonstrating that variation in viremia substantially affects transmission risk.

 

Author summary

The number of people at risk for contracting Zika virus (ZIKV) is difficult to estimate accurately because most infected hosts are asymptomatic and the relationship between variation in host viremia and transmission to local mosquitoes is unclear. Controlling ZIKV transmission remains a major challenge due to lack of basic information on transmission mechanisms and gaps in mechanistic models. Therefore, our study highlights the importance of variation in viral concentration that current modeling efforts ignore, which will enhance our ability to predict the number of people at risk for arbovirus infection, overall disease transmission, and the efficacy of current and future intervention strategies. We demonstrated that increased concentration of ZIKV in the blood significantly increases the probability and the rate at which mosquitoes become infectious, which increases the risk of ZIKV transmission.

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Citation: Tesla B, Demakovsky LR, Packiam HS, Mordecai EA, Rodríguez AD, Bonds MH, et al. (2018) Estimating the effects of variation in viremia on mosquito susceptibility, infectiousness, and R0 of Zika in Aedes aegypti. PLoS Negl Trop Dis 12(8): e0006733. https://doi.org/10.1371/journal.pntd.0006733

Editor: Robert C. Reiner, University of Washington, UNITED STATES

Received: November 22, 2017; Accepted: August 6, 2018; Published: August 22, 2018

Copyright: © 2018 Tesla 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: Data are available at https://doi.org/10.6084/m9.figshare.6953291.v1.

Funding: This study was supported by the National Science Foundation, Grants for Rapid Response Research (NSF-RAPID), award #1640780 (https://www.nsf.gov/awardsearch/showAward?AWD_ID=1640780) (CCM, MHB, EAM, MAB). EAM was supported by National Science Foundation, Division of Environmental Biology, award #1518681 (https://www.nsf.gov/awardsearch/showAward?AWD_ID=1518681&HistoricalAwards=false) and the Stanford University Woods Institute for the Environment Environmental Ventures Program. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. 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: Zika Virus; Mosquitoes; Aedes aegypti.

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#Travel-Associated #Zika Cases and #Threat of Local #Transmission during Global #Outbreak, #California, #USA (Emerg Infect Dis., abstract)

[Source: US Centers for Disease Control and Prevention (CDC), full page: (LINK). Abstract, edited.]

Volume 24, Number 9—September 2018 / Synopsis

Travel-Associated Zika Cases and Threat of Local Transmission during Global Outbreak, California, USA

Charsey Cole Porse  , Sharon Messenger, Duc J. Vugia, Wendy Jilek, Maria Salas, James Watt, and Vicki Kramer

Author affiliations: California Department of Public Health, Sacramento, California, USA (C.C. Porse, W. Jilek, V. Kramer); California Department of Public Health, Richmond, California, USA (S. Messenger, D.J. Vugia, M. Salas, J. Watt)

 

Abstract

Zika and associated microcephaly among newborns were reported in Brazil during 2015. Zika has since spread across the Americas, and travel-associated cases were reported throughout the United States. We reviewed travel-associated Zika cases in California to assess the potential threat of local Zika virus transmission, given the regional spread of Aedes aegypti and Ae. albopictus mosquitoes. During November 2015–September 2017, a total of 588 travel-associated Zika cases were reported in California, including 139 infections in pregnant women, 10 congenital infections, and 8 sexually transmitted infections. Most case-patients reported travel to Mexico and Central America, and many returned during a period when they could have been viremic. By September 2017, Ae. aegypti mosquitoes had spread to 124 locations in California, and Ae. albopictus mosquitoes had spread to 53 locations. Continued human and mosquito surveillance and public health education are valuable tools in preventing and detecting Zika virus infections and local transmission in California.

Keywords: Zika Virus; Zika Congenital Infection; California; USA; Mosquitoes; Aedes aegypti; Aedes albopictus.

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#Temperature drives #Zika virus #transmission: #evidence from empirical and mathematical models (Proc Roy Soc B., abstract)

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

Temperature drives Zika virus transmission: evidence from empirical and mathematical models

Blanka Tesla, Leah R. Demakovsky, Erin A. Mordecai, Sadie J. Ryan, Matthew H. Bonds, Calistus N. Ngonghala, Melinda A. Brindley, Courtney C. Murdock

Published 15 August 2018. DOI: 10.1098/rspb.2018.0795

 

Abstract

Temperature is a strong driver of vector-borne disease transmission. Yet, for emerging arboviruses we lack fundamental knowledge on the relationship between transmission and temperature. Current models rely on the untested assumption that Zika virus responds similarly to dengue virus, potentially limiting our ability to accurately predict the spread of Zika. We conducted experiments to estimate the thermal performance of Zika virus (ZIKV) in field-derived Aedes aegypti across eight constant temperatures. We observed strong, unimodal effects of temperature on vector competence, extrinsic incubation period and mosquito survival. We used thermal responses of these traits to update an existing temperature-dependent model to infer temperature effects on ZIKV transmission. ZIKV transmission was optimized at 29°C, and had a thermal range of 22.7°C–34.7°C. Thus, as temperatures move towards the predicted thermal optimum (29°C) owing to climate change, urbanization or seasonality, Zika could expand north and into longer seasons. By contrast, areas that are near the thermal optimum were predicted to experience a decrease in overall environmental suitability. We also demonstrate that the predicted thermal minimum for Zika transmission is 5°C warmer than that of dengue, and current global estimates on the environmental suitability for Zika are greatly over-predicting its possible range.

Keywords: Zika Virus; Mosquitoes; Aedes aegypti.

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Managing #Aedes aegypti #populations in the first #Zika #transmission zones in the continental #US (Acta Trop., abstract)

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

Acta Trop. 2018 Jul 31. pii: S0001-706X(18)30810-6. doi: 10.1016/j.actatropica.2018.07.031. [Epub ahead of print]

Managing Aedes aegypti populations in the first Zika transmission zones in the continental United States.

Stoddard PK1.

Author information: 1 Department of Biological Sciences, Florida International University, 11200 SW 8th St., Miami, FL 33199, USA. Electronic address: stoddard@fiu.edu.

 

Abstract

The African Zika virus swept across the Pacific, reaching the New World in 2014. In July, 2016, Miami-Dade County, Florida became the locus of the first mosquito-borne Zika transmission zones in the continental United States. Control efforts were guided by the Centers for Disease Control and Prevention, including aerial and truck sprays of adulticides and larvicides. To improve our understanding of how best to fight Zika transmission in an urban environment in the developed world, trap counts of adult Aedes (Stegomyia) aegypti (L.) mosquitoes from the treatment zones were analyzed to determine efficacy of the different insecticide treatments. Analysis revealed that application of four different ester pyrethroid and one non-ester pyrethroid had no statistically significant effect on mosquito counts. Aerial application of naled, a potent organophosphate adulticide, produced significant but short-lived drops in Ae. aegypti counts in the first two applications in the first active transmission zone (Wynwood), then lost some efficacy with subsequent application. In the other active transmission zone (Miami Beach), naled produced no measurable effect in the first three applications, and only a small, transient, and marginally significant reduction in the fourth application. Repeated application of the larvicidal bacterium Bti was accompanied by steady declines of Ae. aegypti populations in both sites. Zika transmission ceased in the first transmission zone, but expanded in the second transmission zone during this period. Specific recommendations are proposed for future treatments of urban mosquitoes.

KEYWORDS: Bti; Miami; Miami Beach; naled; vector control

PMID: 30075097 DOI: 10.1016/j.actatropica.2018.07.031

Keywords: Zika Virus; USA; Florida; Mosquitoes; Aedes aegypti; Insecticides.

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