Isolation and #Genome Phylogenetic Analysis of #Arboviruses, Including #Akabane Virus, from #Mosquitoes Collected in #Hunan Province, #China (Vector Borne Zoo Dis., abstract)

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

Isolation and Genome Phylogenetic Analysis of Arthropod-Borne Viruses, Including Akabane Virus, from Mosquitoes Collected in Hunan Province, China

Yuxi Cao, Shihong Fu, Song Song, Liang Cai, Hong Zhang, Lidong Gao, Lei Cao, Minghua Li, Xiaoyan Gao, Ying He, Huanyu Wang, and Guodong Liang

Published Online: 11 Dec 2018

 

Abstract

This study investigated the abundance of mosquitoes and circulation of mosquito-borne arboviruses from 16 villages in 8 cities of Hunan Province, China, in July–August of 2010 and in August of 2011. In total, 16,076 mosquitoes consisting of seven species from four genera were collected by ultraviolet-light trap. Culex quinquefasciatus was the most common species, accounting for 50.63% (8140/16,076) of the total. Anopheles sinensis (24.26%, 3900/16,076) made up the second most common species, followed by Culex tritaeniorhynchus (9.76%, 1569/16,076). The proportions of Culex pipiens pallens, Armigeres subalbatus, and Culex modestus were 6.7%, 5.2%, and 3.31%, respectively. Fourteen Aedes albopictus were detected. The mosquitoes were identified by morphologic characteristics and frozen in liquid nitrogen. The mosquitoes were pooled, triturated, and centrifuged. The clarified supernatant was used to inoculate monolayers of C6/36 and baby hamster kidney-21 cells. We obtained six virus isolates that caused cytopathic effects. Phylogenetic analysis revealed that two isolates were Akabane virus (AKAV, from A. sinensis and C. quinquefasciatus), two isolates were Japanese encephalitis virus (from C. pipiens pallens and C. quinquefasciatus), and two isolates were Tibet orbivirus (from C. quinquefasciatus and C. tritaeniorhynchus). This is the first report of AKAV isolated from A. sinensis and C. quinquefasciatus in nature in China. The detection of AKAV in these species confirms circulation of AKAV in Hunan province and suggests potential challenges to the prevention and control of arthropod-borne animal viruses in mainland China.

Keywords: Arbovirus; Mosquitoes; Culex spp.; Aedes spp.; Akabane Virus; Hunan; China.

—–

Advertisements

#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: December 7, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006993

 

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 warrants prioritization of SHUV for further research. Additional knowledge is essential to accurately determine the risk for animal and human health, and to assess the risk of future epizootics and epidemics. To gain first insights into the potential involvement of arthropod vectors in SHUV transmission, we have investigated the ability of SHUV to infect and disseminate in laboratory-reared biting midges and 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 lower than 2%. SHUV successfully disseminated in both species of biting midges, but no evidence of transmission in orally exposed mosquitoes was found.

Conclusions/Significance

The results of this study show that different species of Culicoides biting midges are susceptible to infection and dissemination of SHUV, whereas the two mosquito species tested were found not to be susceptible.

 

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 have a significant impact on human and animal health, many arboviruses remain neglected. Shuni virus (SHUV) is a neglected virus with zoonotic potential that was recently associated with severe disease in livestock and wildlife. Isolations of SHUV from field-collected biting midges and mosquitoes suggests that SHUV may be transmitted by these insects. Laboratory-reared biting midge species (Culicoides nubeculosus and C. sonorensis) and mosquito species (Culex pipiens pipiens and Aedes aegypti), that are known to transmit other arboviruses, were exposed to SHUV via an infectious blood meal. SHUV was able to successfully disseminate in both biting midge species, whereas no evidence of infection or transmission in both mosquito species was found. Our results show that SHUV infects and disseminates in two different Culicoides species, suggesting that these insects could play an important role in the disease transmission cycle.

___

Citation: Möhlmann TWR, Oymans J, Wichgers Schreur PJ, Koenraadt CJM, Kortekaas J, Vogels CBF (2018) Vector competence of biting midges and mosquitoes for Shuni virus. PLoS Negl Trop Dis 12(12): e0006993. https://doi.org/10.1371/journal.pntd.0006993

Editor: Hans-Peter Fuehrer, University of Veterinary Medicine, Vienna, AUSTRIA

Received: June 19, 2018; Accepted: November 12, 2018; Published: December 7, 2018

Copyright: © 2018 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; Arbovirus; Shuni Virus; Midges; Mosquitoes.

——

#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.

——

Integrated #Aedes #management for the control of Aedes-borne #diseases (PLoS Negl Trop Dis., abstract)

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

OPEN ACCESS / REVIEW

Integrated Aedes management for the control of Aedes-borne diseases

David Roiz , Anne L. Wilson, Thomas W. Scott, Dina M. Fonseca, Frédéric Jourdain, Pie Müller, Raman Velayudhan, Vincent Corbel

Published: December 6, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006845

 

Abstract

Background

Diseases caused by Aedes-borne viruses, such as dengue, Zika, chikungunya, and yellow fever, are emerging and reemerging globally. The causes are multifactorial and include global trade, international travel, urbanisation, water storage practices, lack of resources for intervention, and an inadequate evidence base for the public health impact of Aedes control tools. National authorities need comprehensive evidence-based guidance on how and when to implement Aedes control measures tailored to local entomological and epidemiological conditions.

Methods and findings

This review is one of a series being conducted by the Worldwide Insecticide resistance Network (WIN). It describes a framework for implementing Integrated Aedes Management (IAM) to improve control of diseases caused by Aedes-borne viruses based on available evidence. IAM consists of a portfolio of operational actions and priorities for the control of Aedes-borne viruses that are tailored to different epidemiological and entomological risk scenarios. The framework has 4 activity pillars: (i) integrated vector and disease surveillance, (ii) vector control, (iii) community mobilisation, and (iv) intra- and intersectoral collaboration as well as 4 supporting activities: (i) capacity building, (ii) research, (iii) advocacy, and (iv) policies and laws.

Conclusions

IAM supports implementation of the World Health Organisation Global Vector Control Response (WHO GVCR) and provides a comprehensive framework for health authorities to devise and deliver sustainable, effective, integrated, community-based, locally adapted vector control strategies in order to reduce the burden of Aedes-transmitted arboviruses. The success of IAM requires strong commitment and leadership from governments to maintain proactive disease prevention programs and preparedness for rapid responses to outbreaks.

 

Author summary

Aedes aegypti and A. albopictus are mosquito species that thrive in towns and cities and can transmit viruses to humans that cause diseases, such as dengue, Zika, chikungunya, and yellow fever. The geographic range of human infection with these viruses is rapidly expanding globally. Even when preventative or therapeutic treatments are available to fight these diseases, controlling the mosquito vector will remain an important control option. We therefore developed a framework called IAM that offers decision-making guidance based on available evidence of effective control of Aedes at different levels of infestation and virus transmission risk. Our work aims to strengthen the capacity of countries at risk of and/or affected by these diseases and vectors so they will be better prepared for existing and emerging Aedes-borne disease threats.

___

Citation: Roiz D, Wilson AL, Scott TW, Fonseca DM, Jourdain F, Müller P, et al. (2018) Integrated Aedes management for the control of Aedes-borne diseases. PLoS Negl Trop Dis 12(12): e0006845. https://doi.org/10.1371/journal.pntd.0006845

Editor: Olaf Horstick, University of Heidelberg, GERMANY

Published: December 6, 2018

Copyright: © 2018 Roiz 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: This review was funded by an award to VC and the WIN network from the World Health Organization’s Special Programme for Research and Training in Tropical Diseases (http://www.who.int/tdr/). DR was partially supported by the ANR grant INVACOST. The funders had no role in the study design, data collection and analysis, nor the writing of the manuscript, nor the decision to publish.

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

Keywords: Arbovirus; Mosquitoes; Aedes spp.

—–

#Antibody responses to #Zika virus proteins in #pregnant and non-pregnant #macaques (PLoS Negl Trop Dis., abstract)

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

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Antibody responses to Zika virus proteins in pregnant and non-pregnant macaques

Anna S. Heffron , Emma L. Mohr , David Baker, Amelia K. Haj, Connor R. Buechler, Adam Bailey, Dawn M. Dudley, Christina M. Newman, Mariel S. Mohns, Michelle Koenig, Meghan E. Breitbach, Mustafa Rasheed, Laurel M. Stewart,  [ … ], David H. O’Connor

Published: November 27, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006903 / This is an uncorrected proof.

 

Abstract

The specificity of the antibody response against Zika virus (ZIKV) is not well-characterized. This is due, in part, to the antigenic similarity between ZIKV and closely related dengue virus (DENV) serotypes. Since these and other similar viruses co-circulate, are spread by the same mosquito species, and can cause similar acute clinical syndromes, it is difficult to disentangle ZIKV-specific antibody responses from responses to closely-related arboviruses in humans. Here we use high-density peptide microarrays to profile anti-ZIKV antibody reactivity in pregnant and non-pregnant macaque monkeys with known exposure histories and compare these results to reactivity following DENV infection. We also compare cross-reactive binding of ZIKV-immune sera to the full proteomes of 28 arboviruses. We independently confirm a purported ZIKV-specific IgG antibody response targeting ZIKV nonstructural protein 2B (NS2B) that was recently reported in ZIKV-infected people and we show that antibody reactivity in pregnant animals can be detected as late as 127 days post-infection (dpi). However, we also show that these responses wane over time, sometimes rapidly, and in one case the response was elicited following DENV infection in a previously ZIKV-exposed animal. These results suggest epidemiologic studies assessing seroprevalence of ZIKV immunity using linear epitope-based strategies will remain challenging to interpret due to susceptibility to false positive results. However, the method used here demonstrates the potential for rapid profiling of proteome-wide antibody responses to a myriad of neglected diseases simultaneously and may be especially useful for distinguishing antibody reactivity among closely related pathogens.

 

Author summary

ZIKV has emerged as a vector-borne pathogen capable of causing serious illness in infected adults and congenital birth defects. The vulnerability of communities to future ZIKV outbreaks will depend, in part, on the prevalence and longevity of protective immunity, thought to be mediated principally by antibodies. We currently lack diagnostic assays able to differentiate ZIKV-specific antibodies from antibodies produced following infection with closely related DENV, and we do not know how long anti-ZIKV responses are detectable. Here we profile antibodies recognizing linear epitopes throughout the entire ZIKV polyprotein, and we profile cross-reactivity with the proteomes of other co-endemic arboviruses. We show that while ZIKV-specific antibody binding can be detected, these responses are generally weak and ephemeral, and false positives may arise through DENV infection. This may complicate efforts to discern ZIKV infection and to determine ZIKV seroprevalence using linear epitope-based assays. The method used in this study, however, has promise as a tool for profiling antibody responses for a broad array of neglected tropical diseases and other pathogens and in distinguishing serology of closely-related viruses.

___

Citation: Heffron AS, Mohr EL, Baker D, Haj AK, Buechler CR, Bailey A, et al. (2018) Antibody responses to Zika virus proteins in pregnant and non-pregnant macaques. PLoS Negl Trop Dis 12(11): e0006903. https://doi.org/10.1371/journal.pntd.0006903

Editor: Pedro F. C. Vasconcelos, Instituto Evandro Chagas, BRAZIL

Received: August 10, 2018; Accepted: October 4, 2018; Published: November 27, 2018

Copyright: © 2018 Heffron 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 data files and code used for analysis are available from https://go.wisc.edu/b726s1.

Funding: This study was supported by the National Institutes of Health grants R01AI116382 and R24OD017850 (ASH, AKH, CRB, AB, DMD, CMN, MK, MEB, MR, LMS, DHO): https://www.nih.gov/. This study was also supported by the Pediatric Infectious Diseases Society Fellowship Award funded by Stanley A. Plotkin and Sanofi Pasteur (ELM). Finally, this study was also supported by the National Institutes of Health National Research Service Award T32 AI078985 (ASH). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests. This manuscript describes the use of a platform provided on an early-access basis by Roche Sequencing Solutions. While scientists from Roche were involved in the experimental design and data analysis, the manuscript was prepared independently from Roche and did not require pre-approval from Roche prior to submission. RSP, EB, HL, JP, and JCT are employed by Roche Sequencing Solutions.

Keywords: Zika Virus; Arbovirus; Animal Models.

——

Beyond members of the #Flaviviridae family, #sofosbuvir also inhibits #chikungunya virus #replication (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Beyond members of the Flaviviridae family, sofosbuvir also inhibits chikungunya virus replication

André C. Ferreira, Patrícia A. Reis, Caroline S. de Freitas, Carolina Q. Sacramento, Lucas Villas Bôas Hoelz, Mônica M. Bastos, Mayara Mattos, Natasha Rocha,Isaclaudia Gomes de Azevedo Quintanilha, Carolina da Silva Gouveia Pedrosa, Leticia Rocha Quintino Souza, Erick Correia Loiola, Pablo Trindade, Yasmine Rangel Vieira,Giselle Barbosa-Lima, Hugo C. de Castro Faria Neto, Nubia Boechat, Stevens K. Rehen, Karin Brüning, Fernando A. Bozza, Patrícia T. Bozza, Thiago Moreno L. Souza

DOI: 10.1128/AAC.01389-18

 

ABSTRACT

Chikungunya virus (CHIKV) causes a febrile disease associated with chronic arthralgia, which may progress to neurological impairment. Chikungunya fever (CF) is an ongoing public health problem in tropical and subtropical regions of the world, where control of the CHIKV vector, Aedes mosquitos, has failed. As there is no vaccine or specific treatment for CHIKV, patients receive only palliative care to alleviate pain and arthralgia. Thus, drug repurposing is necessary to identify antivirals against CHIKV. CHIKV RNA polymerase is similar to the orthologue enzyme of other positive-sense RNA viruses, such as members of the Flaviviridae family. Among the Flaviviridae, not only is hepatitis C virus RNA polymerase susceptible to sofosbuvir, a clinically approved nucleotide analogue, but so is dengue, Zika, and yellow fever virus replication. Here, we found that sofosbuvir was three times more selective in inhibiting CHIKV production in human hepatoma cells than ribavirin, a pan-antiviral drug. Although CHIKV replication in human induced pluripotent stem cell–derived astrocytes was less susceptible to sofosbuvir compared to the hepatoma cells, sofosbuvir nevertheless impaired virus production and cell death in a multiplicity of infection–dependent manner. Sofosbuvir also exhibited antiviral activity in vivo by preventing CHIKV-induced paw edema in adult mice at a dose of 20 mg/kg/day, and prevented mortality in a neonate mouse model at 40 and 80 mg/kg/day doses. Our data demonstrate that a prototypic alphavirus, CHIKV, is also susceptible to sofosbuvir. As sofosbuvir is a clinically approved drug, our findings could pave the way to it becoming a therapeutic option against CF.

Copyright © 2018 American Society for Microbiology. All Rights Reserved.

Keywords: Arbovirus; Alphavirus; Flavivirus; Antivirals; Sofosbuvir.

—–

Vertical #transmission of naturally occurring #Bunyamwera and insect-specific #flavivirus #infections in #mosquitoes from islands and mainland shores of Lakes Victoria and Baringo in #Kenya (PLoS Negl Trop Dis., abstract)

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

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Vertical transmission of naturally occurring Bunyamwera and insect-specific flavivirus infections in mosquitoes from islands and mainland shores of Lakes Victoria and Baringo in Kenya

Yvonne Ukamaka Ajamma, Thomas Ogao Onchuru , Daniel O. Ouso , David Omondi, Daniel K. Masiga, Jandouwe Villinger

Published: November 19, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006949 / This is an uncorrected proof.

 

Abstract

Background

Many arboviruses transmitted by mosquitoes have been implicated as causative agents of both human and animal illnesses in East Africa. Although epidemics of arboviral emerging infectious diseases have risen in frequency in recent years, the extent to which mosquitoes maintain pathogens in circulation during inter-epidemic periods is still poorly understood. This study aimed to investigate whether arboviruses may be maintained by vertical transmission via immature life stages of different mosquito vector species.

Methodology

We collected immature mosquitoes (egg, larva, pupa) on the shores and islands of Lake Baringo and Lake Victoria in western Kenya and reared them to adults. Mosquito pools (≤25 specimens/pool) of each species were screened for mosquito-borne viruses by high-resolution melting analysis and sequencing of multiplex PCR products of genus-specific primers (alphaviruses, flaviviruses, phleboviruses and Bunyamwera-group orthobunyaviruses). We further confirmed positive samples by culturing in baby hamster kidney and Aedes mosquito cell lines and re-sequencing.

Principal findings

Culex univittatus (2/31pools) and Anopheles gambiae (1/77 pools) from the Lake Victoria region were positive for Bunyamwera virus, a pathogenic virus that is of public health concern. In addition, Aedes aegypti (3/50), Aedes luteocephalus (3/13), Aedes spp. (2/15), and Culex pipiens (1/140) pools were positive for Aedes flaviviruses at Lake Victoria, whereas at Lake Baringo, three pools of An. gambiae mosquitoes were positive for Anopheles flavivirus. These insect-specific flaviviruses (ISFVs), which are presumably non-pathogenic to vertebrates, were found in known medically important arbovirus and malaria vectors.

Conclusions

Our results suggest that not only ISFVs, but also a pathogenic arbovirus, are naturally maintained within mosquito populations by vertical transmission, even in the absence of vertebrate hosts. Therefore, virus and vector surveillance, even during inter-epidemics, and the study of vector-arbovirus-ISFV interactions, may aid in identifying arbovirus transmission risks, with the potential to inform control strategies that lead to disease prevention.

 

Author summary

The East African region is endemic to diverse mosquito-transmitted arboviruses, though little is known about the role of vertical transmission in maintaining these viruses within mosquito vector populations during inter-epidemic periods. We sampled mosquito larvae from the Lake Baringo and Lake Victoria regions of Kenya and reared them to adults in the laboratory before screening them for mosquito-associated viruses by multiplex RT-PCR-HRM, cell culture, and sequencing. From the Lake Victoria region, we detected the arbovirus, Bunyamwera, which can cause febrile illness in humans, in Culex univittatus and vector competent Anopheles gambiaemosquitoes. We also identified diverse insect-specific flaviviruses in Aedes aegypti, Aedes luteocephalus, Aedes spp. and Culex pipiens mosquitoes. From the Lake Baringo region, we detected Anopheles flavivirus in An. gambiae mosquitoes. These findings demonstrate that naturally occurring vertical transmission potentially maintains viruses in circulation within the sampled vector species populations. Therefore, mosquitoes may potentially transmit a pathogenic arbovirus during their first bite after emergence. Because various insect-specific flaviviruses have recently been found to either inhibit or enhance replication of specific arboviruses in mosquitoes, their vertical transmission, as observed in this study, has implications as to their potential impact on both horizontal and vertical transmission of medically important arboviruses.

___

Citation: Ajamma YU, Onchuru TO, Ouso DO, Omondi D, Masiga DK, Villinger J (2018) Vertical transmission of naturally occurring Bunyamwera and insect-specific flavivirus infections in mosquitoes from islands and mainland shores of Lakes Victoria and Baringo in Kenya. PLoS Negl Trop Dis 12(11): e0006949. https://doi.org/10.1371/journal.pntd.0006949

Editor: Michael J. Turell, INDEPENDENT RESEARCHER, UNITED STATES

Received: May 3, 2018; Accepted: October 26, 2018; Published: November 19, 2018

Copyright: © 2018 Ajamma 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 ISFV sequences are available from the GenBank nucleotide database (accession MG372051-MG372060, MK015647- MK015648).

Funding: This work was supported by the Swedish International Development Cooperation Agency (Sida) (www.sida.se), grant number 75000529 to YUA as an African Regional Postgraduate Programme in Insect Science (ARPPIS) scholar; and institutional financial support from UK Aid (www.ukaiddirect.org) from the UK Government; Sida; the Swiss Agency for Development and Cooperation (SDC) (www.eda.admin.ch/sdc); and the Kenyan Government (www.mygov.go.ke). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The views expressed herein do not necessarily reflect the official opinion of the donors.

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

Keywords: Arbovirus; Flavivirus; Orthobunyavirus; Bunyamwera Virus; Mosquitoes; Culex spp.; Anopheles spp.; Kenya.

——