Abstract: Eastern Equine Encephalitis (EEE) (Togaviridae, Alphavirus) is a highly pathogenic mosquito-borne arbovirus that circulates in an enzootic cycle involving Culiseta melanura mosquitoes and wild Passeriformes birds in freshwater swamp habitats. Recently, the northeastern United States has experienced an intensification of virus activity with increased human involvement and northward expansion into new regions. In addition to its principal role in enzootic transmission of EEE virus among avian hosts, recent studies on the blood-feeding behavior of Cs. melanura throughout its geographic range suggest that this mosquito may also be involved in epizootic / epidemic transmission to equines and humans in certain locales. Variations in blood feeding behavior may be a function of host availability, environmental factors, and/or underlying genetic differences among regional populations. Despite the importance of Cs. melanura in transmission and maintenance of EEE virus, the genetics of this species remains largely unexplored. To investigate the occurrence of genetic variation in Cs. melanura, the genome of this mosquito vector was sequenced resulting in a draft genome assembly of 1.28 gigabases with a contig N50 of 93.36 kilobases. Populations of Cs. melanura from 10 EEE virus foci in the eastern North America were genotyped with double-digest RAD-seq. Following alignment of reads to the reference genome, variant calling, and filtering, 40,384 SNPs were retained for downstream analyses. Subsequent analyses revealed genetic differentiation between northern and southern populations of this mosquito species. Moreover, limited fine-scale population structure was detected throughout northeastern North America, suggesting local differentiation of populations but also a history of ancestral polymorphism or contemporary gene flow. Additionally, a genetically distinct cluster was identified predominantly at two northern sites. This study elucidates the first evidence of fine-scale population structure in Cs. melanura throughout its eastern range and detects evidence of gene flow between populations in northeastern North America. This investigation provides the groundwork for examining the consequences of genetic variations in the populations of this mosquito species that could influence vector-host interactions and the risk of human and equine infection with EEE virus.
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research focuses on the genomic differentiation of the Culiseta melanura mosquito, the main carrier of Eastern Equine Encephalitis virus (EEE) in the United States, which reveals potential genetic variations that could influence how the species interacts with hosts and the associated virus transmission risks to humans and horses.
Research Overview
The research aims to understand the population genomics of Culiseta melanura mosquitoes, the principal vector of Eastern Equine Encephalitis virus.
Recent activity increases of the EEE virus in the northeastern United States and its expanding reach into new regions drew the attention of researchers.
The study further highlights the mosquito’s potential role in epidemic transmissions to horses and humans based on observed variations in blood-feeding behavior, which can be influenced by host availability, environmental factors, or possibly genetic variations within regional populations.
Methods and Results
To gain insights on genetic variations in the species, the team sequenced the genome of the mosquito, resulting in a 1.28-gigabase draft genome assembly with a contig N50 of 93.36 kilobases.
Double-digest RAD-seq was used to genotype populations of Cs. melanura from 10 different EEE virus focal points in eastern North America.
After aligning the reads to the reference genome and going through variant calling and filtering, 40,384 single-nucleotide polymorphisms (SNPs) were retained for further analysis.
These analyses revealed genetic differentiation between northern and southern populations. A unique genetic cluster was also discovered primarily at two northern sites.
Interestingly, there was evidence of limited fine-scale population structure within northeastern North America, suggesting both local differentiation of populations and a history of ancestral polymorphism or ongoing gene flow.
Concluding Remarks
Notably, the study provides the first evidence of fine-scale population structure in Cs. melanura in its eastern range along with indications of gene flow between northeastern North American populations.
Overall, this research sets the stage for exploring the implications of these genetic variations on vector-host interactions in this mosquito species and the associated risk to humans and horses of EEE virus infection.
Cite This Article
APA
Soghigian J, Andreadis TG, Molaei G.
(2018).
Population genomics of Culiseta melanura, the principal vector of Eastern equine encephalitis virus in the United States.
PLoS Negl Trop Dis, 12(8), e0006698.
https://doi.org/10.1371/journal.pntd.0006698
Department of Environmental Sciences, Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, Connecticut, United States of America.
Andreadis, Theodore G
Department of Environmental Sciences, Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, Connecticut, United States of America.
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.
Molaei, Goudarz
Department of Environmental Sciences, Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, Connecticut, United States of America.
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.
MeSH Terms
Animal Distribution
Animals
Cluster Analysis
Culicidae / genetics
Culicidae / virology
DNA / genetics
Encephalitis Virus, Eastern Equine / physiology
Female
Genetic Variation
Genome
Genotype
Mosquito Vectors / genetics
Mosquito Vectors / virology
Multivariate Analysis
Polymerase Chain Reaction
United States
Grant Funding
U01 CK000509 / NCEZID CDC HHS
Conflict of Interest Statement
The authors have declared that no competing interests exist.
References
This article includes 83 references
Deresiewicz RL, Thaler SJ, Hsu L, Zamani AA. Clinical and neuroradiographic manifestations of eastern equine encephalitis.. N Engl J Med 1997 Jun 26;336(26):1867-74.
Morris CD. Eastern equine encephalomyelitis In: Monath TP, editor. The arboviruses: epidemiology and ecology. Boca Raton: CRC Press; 1988. pp. 1–20.
Howard JJ, Morris CD, Emord DE, Grayson MA. Epizootiology of eastern equine encephalitis virus in upstate New York, USA. VII. Virus surveillance 1978-85, description of 1983 outbreak, and series conclusions.. J Med Entomol 1988 Nov;25(6):501-14.
Saxton-Shaw KD, Ledermann JP, Kenney JL, Berl E, Graham AC, Russo JM, Powers AM, Mutebi JP. The first outbreak of eastern equine encephalitis in Vermont: outbreak description and phylogenetic relationships of the virus isolate.. PLoS One 2015;10(6):e0128712.
Morris CD, Zimmerman RH, Edman JD. Epizootiology of eastern equine encephalomyelitis virus in upstate New York, USA. II. Population dynamics and vector potential of adult Culiseta melanura (Diptera: Culicidae) in relation to distance from breeding site.. J Med Entomol 1980 Sep 30;17(5):453-65.
Darsie RF, Ward RA. Identification and geographical distribution of the mosquitos of North America, north of Mexico: University Press of Florida; 2005.
Molaei G, Armstrong PM, Graham AC, Kramer LD, Andreadis TG. Insights into the recent emergence and expansion of eastern equine encephalitis virus in a new focus in the Northern New England USA.. Parasit Vectors 2015 Oct 9;8:516.
Molaei G, Andreadis TG, Armstrong PM, Thomas MC, Deschamps T, Cuebas-Incle E, Montgomery W, Osborne M, Smole S, Matton P, Andrews W, Best C, Cornine F 3rd, Bidlack E, Texeira T. Vector-host interactions and epizootiology of eastern equine encephalitis virus in Massachusetts.. Vector Borne Zoonotic Dis 2013 May;13(5):312-23.
Molaei G, Oliver J, Andreadis TG, Armstrong PM, Howard JJ. Molecular identification of blood-meal sources in Culiseta melanura and Culiseta morsitans from an endemic focus of eastern equine encephalitis virus in New York.. Am J Trop Med Hyg 2006 Dec;75(6):1140-7.
Armstrong PM, Andreadis TG. Eastern equine encephalitis virus in mosquitoes and their role as bridge vectors.. Emerg Infect Dis 2010 Dec;16(12):1869-74.
Mahmood F, Crans WJ. Laboratory colonization of Culiseta melanura from southern New Jersey. Proceedings of the New Jersey Mosquito Control Association 1994 pp. 93–95.
Koren S, Walenz BP, Berlin K, Miller JR, Bergman NH, Phillippy AM. Canu: scalable and accurate long-read assembly via adaptive k-mer weighting and repeat separation.. Genome Res 2017 May;27(5):722-736.
Giraldo-Calderón GI, Emrich SJ, MacCallum RM, Maslen G, Dialynas E, Topalis P, Ho N, Gesing S, Madey G, Collins FH, Lawson D. VectorBase: an updated bioinformatics resource for invertebrate vectors and other organisms related with human diseases.. Nucleic Acids Res 2015 Jan;43(Database issue):D707-13.
Wickham H. Ggplot2: elegant graphics for data analysis. Springer; 2009.
O’Malley C. Guidelines for larval surveillance. Proceedings of the Seventy-Sixth Annual Meeting of the New Jersey Mosquito Control Association 1989 pp. 44–55.
Peterson BK, Weber JN, Kay EH, Fisher HS, Hoekstra HE. Double digest RADseq: an inexpensive method for de novo SNP discovery and genotyping in model and non-model species.. PLoS One 2012;7(5):e37135.
Andrews KR, Good JM, Miller MR, Luikart G, Hohenlohe PA. Harnessing the power of RADseq for ecological and evolutionary genomics.. Nat Rev Genet 2016 Feb;17(2):81-92.
Langmead B, Trapnell C, Pop M, Salzberg SL. Ultrafast and memory-efficient alignment of short DNA sequences to the human genome.. Genome Biol 2009;10(3):R25.
Chang CC, Chow CC, Tellier LC, Vattikuti S, Purcell SM, Lee JJ. Second-generation PLINK: rising to the challenge of larger and richer datasets.. Gigascience 2015;4:7.
Lischer HE, Excoffier L. PGDSpider: an automated data conversion tool for connecting population genetics and genomics programs.. Bioinformatics 2012 Jan 15;28(2):298-9.
Excoffier L, Smouse PE, Quattro JM. Analysis of molecular variance inferred from metric distances among DNA haplotypes: application to human mitochondrial DNA restriction data.. Genetics 1992 Jun;131(2):479-91.
Pembleton LW, Cogan NO, Forster JW. StAMPP: an R package for calculation of genetic differentiation and structure of mixed-ploidy level populations.. Mol Ecol Resour 2013 Sep;13(5):946-52.
Malinsky M, Trucchi E, Lawson DJ, Falush D. RADpainter and fineRADstructure: Population Inference from RADseq Data.. Mol Biol Evol 2018 May 1;35(5):1284-1290.
Oksanen J, Blanchet FG, Friendly M, Kindt R, Legendre P, McGlinn D. vegan: Community Ecology Package. 2017.
Hervé M. RVAideMemoire: Testing and Plotting Procedures for Biostatistics. 2018.
Kamvar ZN, Tabima JF, Grünwald NJ. Poppr: an R package for genetic analysis of populations with clonal, partially clonal, and/or sexual reproduction.. PeerJ 2014;2:e281.
Kamvar ZN, Brooks JC, Grünwald NJ. Novel R tools for analysis of genome-wide population genetic data with emphasis on clonality.. Front Genet 2015;6:208.
Excoffier L, Lischer HE. Arlequin suite ver 3.5: a new series of programs to perform population genetics analyses under Linux and Windows.. Mol Ecol Resour 2010 May;10(3):564-7.
Batovska J, Cogan NO, Lynch SE, Blacket MJ. Using Next-Generation Sequencing for DNA Barcoding: Capturing Allelic Variation in ITS2.. G3 (Bethesda) 2017 Jan 5;7(1):19-29.
Kearse M, Moir R, Wilson A, Stones-Havas S, Cheung M, Sturrock S, Buxton S, Cooper A, Markowitz S, Duran C, Thierer T, Ashton B, Meintjes P, Drummond A. Geneious Basic: an integrated and extendable desktop software platform for the organization and analysis of sequence data.. Bioinformatics 2012 Jun 15;28(12):1647-9.
Gerritsen H. mapplots: Data Visualisation on Maps. 2014.
Chen XG, Jiang X, Gu J, Xu M, Wu Y, Deng Y, Zhang C, Bonizzoni M, Dermauw W, Vontas J, Armbruster P, Huang X, Yang Y, Zhang H, He W, Peng H, Liu Y, Wu K, Chen J, Lirakis M, Topalis P, Van Leeuwen T, Hall AB, Jiang X, Thorpe C, Mueller RL, Sun C, Waterhouse RM, Yan G, Tu ZJ, Fang X, James AA. Genome sequence of the Asian Tiger mosquito, Aedes albopictus, reveals insights into its biology, genetics, and evolution.. Proc Natl Acad Sci U S A 2015 Nov 3;112(44):E5907-15.
McBride CS, Baier F, Omondi AB, Spitzer SA, Lutomiah J, Sang R, Ignell R, Vosshall LB. Evolution of mosquito preference for humans linked to an odorant receptor.. Nature 2014 Nov 13;515(7526):222-7.
Zhou X, Rinker DC, Pitts RJ, Rokas A, Zwiebel LJ. Divergent and conserved elements comprise the chemoreceptive repertoire of the nonblood-feeding mosquito Toxorhynchites amboinensis.. Genome Biol Evol 2014 Oct 16;6(10):2883-96.
Mitchell SN, Kakani EG, South A, Howell PI, Waterhouse RM, Catteruccia F. Mosquito biology. Evolution of sexual traits influencing vectorial capacity in anopheline mosquitoes.. Science 2015 Feb 27;347(6225):985-8.
McFarlane M, Arias-Goeta C, Martin E, O'Hara Z, Lulla A, Mousson L, Rainey SM, Misbah S, Schnettler E, Donald CL, Merits A, Kohl A, Failloux AB. Characterization of Aedes aegypti innate-immune pathways that limit Chikungunya virus replication.. PLoS Negl Trop Dis 2014 Jul;8(7):e2994.
Jiang X, Peery A, Hall AB, Sharma A, Chen XG, Waterhouse RM, Komissarov A, Riehle MM, Shouche Y, Sharakhova MV, Lawson D, Pakpour N, Arensburger P, Davidson VL, Eiglmeier K, Emrich S, George P, Kennedy RC, Mane SP, Maslen G, Oringanje C, Qi Y, Settlage R, Tojo M, Tubio JM, Unger MF, Wang B, Vernick KD, Ribeiro JM, James AA, Michel K, Riehle MA, Luckhart S, Sharakhov IV, Tu Z. Genome analysis of a major urban malaria vector mosquito, Anopheles stephensi.. Genome Biol 2014 Sep 23;15(9):459.
Carvalho DO, McKemey AR, Garziera L, Lacroix R, Donnelly CA, Alphey L, Malavasi A, Capurro ML. Suppression of a Field Population of Aedes aegypti in Brazil by Sustained Release of Transgenic Male Mosquitoes.. PLoS Negl Trop Dis 2015;9(7):e0003864.
Jones PL, Pask GM, Rinker DC, Zwiebel LJ. Functional agonism of insect odorant receptor ion channels.. Proc Natl Acad Sci U S A 2011 May 24;108(21):8821-5.
Raphemot R, Rouhier MF, Hopkins CR, Gogliotti RD, Lovell KM, Hine RM, Ghosalkar D, Longo A, Beyenbach KW, Denton JS, Piermarini PM. Eliciting renal failure in mosquitoes with a small-molecule inhibitor of inward-rectifying potassium channels.. PLoS One 2013;8(5):e64905.
Nazareno AG, Bemmels JB, Dick CW, Lohmann LG. Minimum sample sizes for population genomics: an empirical study from an Amazonian plant species.. Mol Ecol Resour 2017 Nov;17(6):1136-1147.
Willing EM, Dreyer C, van Oosterhout C. Estimates of genetic differentiation measured by F(ST) do not necessarily require large sample sizes when using many SNP markers.. PLoS One 2012;7(8):e42649.
Apperson CS, Hassan HK, Harrison BA, Savage HM, Aspen SE, Farajollahi A, Crans W, Daniels TJ, Falco RC, Benedict M, Anderson M, McMillen L, Unnasch TR. Host feeding patterns of established and potential mosquito vectors of West Nile virus in the eastern United States.. Vector Borne Zoonotic Dis 2004 Spring;4(1):71-82.
French HM, Demitroff M, Forman SL, Newell WL. A chronology of Late-Pleistocene permafrost events in southern New Jersey, Eastern USA. Permafr Periglac Process 2007;18: 49–59.
Drummond AJ, Rambaut A, Shapiro B, Pybus OG. Bayesian coalescent inference of past population dynamics from molecular sequences.. Mol Biol Evol 2005 May;22(5):1185-92.
Howard JJ, White DJ, Muller SL. Mark-recapture studies on the Culiseta (Diptera: Culicidae) vectors of eastern equine encephalitis virus.. J Med Entomol 1989 May;26(3):190-9.
Brown SC, Cormier J, Tuan J, Lier AJ, McGuone D, Armstrong PM, Kaddouh F, Parikh S, Landry ML, Gobeske KT. Four Human Cases of Eastern Equine Encephalitis in Connecticut, USA, during a Larger Regional Outbreak, 2019. Emerg Infect Dis 2021 Aug;27(8):2042-51.
Howard JJ, Oliver J, Dupuis Ii AP, Ngo KA, Stout J, Zink SD, Banker E, Maffei JG, Kramer LD, Sherwood JA, Ciota AT. Eastern equine encephalitis virus and identification of host bloodmeal sources from individual Culiseta melanura (Diptera: Culicidae) at an enzootic focus in central New York State. J Med Entomol 2026 Jan 20;63(1).
Wang S, Mahalingam S, Merits A. Alphavirus nsP2: A Multifunctional Regulator of Viral Replication and Promising Target for Anti-Alphavirus Therapies. Rev Med Virol 2025 Mar;35(2):e70030.