David W. Severson Professor Emeritus

Research Interests:

The Severson lab has broad interest in mosquito genetics and genomics, with a primary goal of understanding the molecular genetics of disease transmission by mosquitoes. Mosquito-borne diseases have emerged or re-emerged as significant human health problems due to a number of factors including lack of progress in vaccine development, emergence of drug resistance in pathogens and insecticide resistance in mosquitoes, and the decline in socioeconomic conditions in many disease endemic countries that limits disease monitoring and mosquito control efforts.

Vector competence and many other phenotypes of interest are quantitative traits that involve the combined effects of multiple genes. The Severson lab has performed quantitative trait locus (QTL) mapping of several traits including several pathogens and important traits like autogeny, diapause, and body size. These studies defined genome regions containing primary genes driving these phenotypes, and in some cases, showed strong correlations between some genome regions and multiple phenotypes.

Availability and annotation of whole genome sequence information has facilitated whole transcriptome studies the Severson Las has conducted on response to dengue virus (DENV) infection in susceptible and refractory A. aegypti genetic backgrounds. Our results showed coordinated expression of genes associated with a susceptible or refractory response as well as genes that showed coordinated expression to DENV infection irrespective of genetic background. More recent studies with Culex pipiens revealed transcriptome responses to diapause inducing conditions, including some key pathways that drive a response.

Research in the Severson lab has also included considerable effort to examine the population genetics and basic biology of A. aegypti in dengue endemic field sites, primarily in Trinidad and Tobago. Results have revealed evidence for population substructure that likely reflected the results of intensive vector control programs on population variability. Studies on the impact of environmental conditions on larval development showed that daily temperature cycles impact potential breeding container output and resulted in wide phenotypic plasticity in body size among the adult mosquitoes. Other studies employed DNA markers to examine oviposition behavior by individual females, characterize a meiotic drive system, and demonstrated the impact of anthropogenic features like major highways on mosquito migration.

Biography:

• Honorary Professor, Department of Life Sciences, University of the West Indies, St. Augustine, Trinidad 2017-2020
• Adjunct Professor of Medical and Molecular Genetics, Indiana University School of Medicine - South Bend, Indiana 2008-Present
• Professor 2001-Present
• Associate Professor 1997-2001
• Senior Scientist, University of Wisconsin 1994-1997
• Associate Scientist, University of Wisconsin 1992-1994
• Assistant Scientist, University of Wisconsin 1986-1992
• Research Associate, University of Wisconsin 1983-1986
• Ph.D., University of Wisconsin 1983
• M.Sc., University of Wisconsin, LaCrosse 1978
• B.A., Winona State University 1975

Selected Papers:

• Eng, M.W., A. Clemons, C. Hill, R. Engel, D.W. Severson and S.K. Behura. 2018. Multifaceted functional implications of an endogenously expressed tRNA fragment in the vector mosquito Aedes aegypti. PLoS Neglected Tropical Diseases 12:e0006186.
• Hapairai, L.K., K. Mysore, Y. Chen, E.I. Harper, M.P. Scheel, A.M. Lesnik, D.W. Severson, N. Wei and M Duman-Scheel. 2017. Lure-and-kill interfering RNA larvicides targeting neural genes in the human disease vector mosquito Aedes aegypti. Scientific Reports 7:13223.
• Kang, D.S., J. Alcalay, D.D. Lovin, J.M. Cunningham, M.W. Eng, D.D. Chadee and D.W. Severson. 2017. Larval stress alters dengue virus susceptibility in Aedes aegypti (L.) adult females. Acta Tropica 174:97-101.
• Eng, M.W., M.N. van Zuylen and D.W. Severson. 2016. Apoptosis-related genes control autophagy and influence DENV-2 infection in the mosquito vector, Aedes aegypti. Insect Biochemistry and Molecular Biology 76:70-83.
• Lima, A., D.D. Lovin, P.V. Hickner and D.W. Severson. 2016. Evidence for an overwintering population of Aedes aegypti in Capitol Hill neighborhood of Washington DC. American Journal of Tropical Medicine and Hygiene 94:231-235.
• Behura, S.K., C. Gomez-Machorro, B.W. Harker, B. deBruyn, D.D. Lovin, R.R. Hemme, A. Mori, J. Romero-Severson and D.W. Severson. 2011. Global cross-talk of genes of the mosquito Aedes aegypti in response to dengue virus infection. PLoS Neglected Tropical Diseases 5:e1385.
• Schneider, J.R., D.D. Chadee, A. Mori, J. Romero-Severson and D.W. Severson. 2011. Heritability and adaptive phenotypic plasticity of adult body size in the mosquito Aedes aegypti with implications for dengue vector competence. Infection, Genetics and Evolution 11:11-16.
• Nene, V, Wortman, J.R., Lawson, D., Haas, B., (+89 co-authors) and D.W. Severson. 2007. Genome sequence of Aedes aegypti, a major arbovirus vector. Science 316:1718-1722.
• Hickner, P.V., A. Mori, E. Zeng, J.C. Tan and D.W. Severson. 2015. Whole transcriptome responses among females of the filariasis and arbovirus vector mosquito Culex pipiens implicate TGF-B signaling and chromatin modification as key drivers of diapause induction. Functional & Integrative Genomics Epub Jan 30, PMID: 25634120.