Elissa Hallem*

Our research focuses on sensory circuit function in parasitic and free-living animals, and lies at the interface of neurobiology and parasitology. Nearly all organisms respond to sensory stimuli, but how sensory circuits specify behavior is poorly understood. We are investigating the neural basis of sensory behaviors in the context of human parasitism. We use parasitic nematodes and the free-living nematode C. elegans as models. The goals of our research are to understand how parasitic worms use sensory cues to locate and infect hosts, how sensory circuits of parasitic animals differ from those of free-living animals to enable parasitic behaviors, and how sensory microcircuits generate flexible outputs. Our research addresses fundamental questions of sensory circuit function and evolution. In addition, human-parasitic worms are a major cause of morbidity worldwide, and a better understanding of their behaviors may enable the development of novel strategies for preventing infections.


Hallem Lab Website

Research Interests:

sensory plasticity, parasitology, parasites, parasite, host-seeking behavior, sensory neurobiology, skin-penetrating nematodes, sensory neural circuits, Strongyloides stercoralis, parasitic nematodes, neuroscience, nematodes, chemosensation, chemosensory valence, host-pathogen interactions,


Castelletto ML, Akimori D, Patel R, Schroeder NE, Hallem EA. Introduction to Strongyloides stercoralis Anatomy. J Nematol. 2024 Mar; 56(1):20240019. view on PubMed

Patel R, Bryant AS, Castelletto ML, Walsh B, Akimori D, Hallem EA. The generation of stable transgenic lines in the human-infective nematode Strongyloides stercoralis. G3 (Bethesda). 2024 Jun 05. view on PubMed

Banerjee, N., Rojas Palato, E.J., Shih, P.Y., Sternberg, P.W., and Hallem, E.A. Distinct neurogenetic mechanisms establish the same chemosensory valence state at different life stages in Caenorhabditis elegans. G3. 2024; 14:jkad271. view on PubMed

Bryant AS, Akimori D, Stoltzfus JDC, Hallem EA. A standard workflow for community-driven manual curation of Strongyloides genome annotations. Phil Trans R Soc B. 2023; 379:20220443. view on PubMed

McClure CR, Patel R, Hallem EA . Invade or die: behaviors and biochemical mechanisms that drive skin penetration in Strongyloides and other skin-penetrating nematodes. Phil Trans R Soc B. 2023; 379:20220434. view on PubMed

Al-Jawabreh R, Anderson R, Atkinson LE, Bickford-Smith J, Bradbury RS, Breloer M, Bryant AS, Buonfrate D, Cadd LC, Crooks B, Deiana M, Grant W, Hallem E, Hedtke SM, Hunt V, Khieu V, Kikuchi T, Kounosu A, Lastik D, van Lieshout L, Liu Y, McSorley HJ, McVeigh P, Mousley A, Murcott B, Nevin WD, Nosková E, Pomari E, Reynolds K, Ross K, Streit A, Suleiman M, Tiberti N, Viney M. Strongyloides questions-a research agenda for the future. Phil Trans R Soc B. 2023; 379:20230004. view on PubMed

Castelletto ML, Akimori D, Patel R, Schroeder NE, Hallem EA. Introduction to Strongyloides stercoralis Anatomy. WormAtlas. 2023. view on PubMed

Banerjee N, Shih PY, Rojas Palato EJ, Sternberg PW, Hallem EA. Differential processing of a chemosensory cue across life stages sharing the same valence state in Caenorhabditis elegans. Proc Natl Acad Sci USA. 2023; 120:e2218023120. view on PubMed

Atkinson LE, Hallem EA. Editorial - Strongyloides research in the post-genomics era. Mol Biochem Parasitol. 2022; 252:111522. view on PubMed

Wheeler NJ, Hallem EA, Zamanian M. Making sense of sensory behaviors in vector-borne helminths. Trends Parasitol. 2022; 38:841-853. view on PubMed

Mendez P, Walsh B, Hallem EA. Using newly optimized genetic tools to probe Strongyloides sensory behaviors. Mol Biochem Parasitol. 2022; 250:111491. view on PubMed

Bryant AS, Ruiz F, Lee JH, Hallem EA. The neural basis of heat seeking in a human-infective parasitic worm. Curr Biol. 2022; 32:2206-2221. view on PubMed

Patel R, Hallem EA. Olfaction: One receptor drives opposite behaviors. Curr Biol. 2022; 32:R93-R96. view on PubMed

Castelletto ML, Hallem EA. Generating Transgenics and Knockouts in Strongyloides Species by Microinjection. J Vis Exp. 2021; 176:10.3791/63023. view on PubMed

Chavez IN, Brown TM, Assié A, Bryant AS, Samuel BS, Hallem EA. Skin-penetrating nematodes exhibit life-stage-specific interactions with host-associated and environmental bacteria. BMC Biol. 2021; 19:221. view on PubMed

Bryant AS, Hallem EA. The Wild Worm Codon Adapter: a web tool for automated codon adaptation of transgenes for expression in non-Caenorhabditis nematodes. G3. 2021; 11:jkab146. view on PubMed

Carstensen HR, Villalon RM, Banerjee N, Hallem EA, Hong RL. Steroid hormone pathways coordinate developmental diapause and olfactory remodeling in Pristionchus pacificus. Genetics. 2021; 218:iyab071. view on PubMed

Bryant AS, DeMarco SF, Hallem EA. Strongyloides RNA-seq Browser: a web-based software platform for on-demand bioinformatics analyses of Strongyloides species. G3. 2021; 11:jkab104. view on PubMed

Gang SS, Castelletto ML, Yang E, Ruiz F, Brown TM, Bryant AS, Grant WN, Hallem EA. Chemosensory mechanisms of host seeking and infectivity in skin-penetrating nematodes. Proc Natl Acad Sci USA. 2020; 117:17913-17923. view on PubMed

Banerjee N, Hallem EA. The role of carbon dioxide in nematode behavior and physiology. Parasitol. 2020; 147:841-854. view on PubMed

Castelletto ML, Gang SS, Hallem EA. Recent advances in functional genomics for parasitic nematodes of mammals. J Exp Biol. 2020; 223:jeb206482. view on PubMed

Banerjee N, Hallem EA. Decoding Inter-individual Variability in Experience-Dependent Behavioral Plasticity. Neuron. 2020; 105:7-9. view on PubMed

Rengarajan S, Yankura KA, Guillermin ML, Fung W, Hallem EA. Feeding state sculpts a circuit for sensory valence in Caenorhabditis elegans. Proc Natl Acad Sci USA. 2019; 116:1776-1781. view on PubMed

Bryant AS, Hallem EA. Terror in the dirt: Sensory determinants of host seeking in soil-transmitted mammalian-parasitic nematodes. Int J Parasitol Drugs Drug Resist. 2018; 8:496-510. view on PubMed

Bryant AS, Hallem EA. Temperature-dependent behaviors of parasitic helminths. Neurosci Lett. 2018; 687:290-303. view on PubMed

Bryant AS, Ruiz F, Gang SS, Castelletto ML, Lopez JB, Hallem EA. A Critical Role for Thermosensation in Host Seeking by Skin-Penetrating Nematodes. Curr Biol. 2018; 28:2338-2347. view on PubMed

Banerjee N, Hallem E. Sexual Dimorphisms: How Sex-Shared Neurons Generate Sex-Specific Behaviors. Curr Biol. 2018; 28:R254-R256. view on PubMed

Ruiz F, Castelletto ML, Gang SS, Hallem EA. Experience-dependent olfactory behaviors of the parasitic nematode Heligmosomoides polygyrus. PLoS Pathog. 2017; 13:e1006709. view on PubMed

Gang SS, Castelletto ML, Bryant AS, Yang E, Mancuso N, Lopez JB, Pellegrini M, Hallem EA. Targeted mutagenesis in a human-parasitic nematode. PLoS Pathog. 2017; 13:e1006675. view on PubMed

Guillermin ML, Carrillo MA, Hallem EA. A Single Set of Interneurons Drives Opposite Behaviors in C. elegans. Curr Biol. 2017; 27:2630-2639. view on PubMed

Park HB, Sampathkumar P, Perez CE, Lee JH, Tran J, Bonanno JB, Hallem EA, Almo SC, Crawford JM. Stilbene epoxidation and detoxification in a Photorhabdus luminescens-nematode symbiosis. J Biol Chem. 2017; 292:6680-6694. view on PubMed

Cevallos JA, Okubo RP, Perlman SJ, Hallem EA. Olfactory Preferences of the Parasitic Nematode Howardula aoronymphium and its Insect Host Drosophila falleni. J Chem Ecol. 2017; 43:362-373. view on PubMed

Rengarajan S, Hallem EA. Olfactory circuits and behaviors of nematodes. Curr Opin Neurobiol. 2016; 41:136-148. view on PubMed

Gang SS, Hallem EA. Mechanisms of host seeking by parasitic nematodes. Mol Biochem Parasitol. 2016; 208:23-32. view on PubMed

Lee JH, Dillman AR, Hallem EA. Temperature-dependent changes in the host-seeking behaviors of parasitic nematodes. BMC Biol. 2016; 14:36. view on PubMed

Peña JM, Carrillo MA, Hallem EA. Variation in the susceptibility of Drosophila to different entomopathogenic nematodes. Infect Immun. 2015; 83:1130-1138. view on PubMed

Castelletto ML, Gang SS, Okubo RP, Tselikova AA, Nolan TJ, Platzer EG, Lok JB, Hallem EA. Diverse host-seeking behaviors of skin-penetrating nematodes. PLoS Pathog. 2014; 10:e1004305. view on PubMed

Carrillo MA, Guillermin ML, Rengarajan S, Okubo RP, Hallem EA. O2-sensing neurons control CO2 response in C. elegans. J Neurosci. 2013; 33:9675-983. view on PubMed

Chaisson KE, Hallem EA. Chemosensory behaviors of parasites. Trends Parasitol. 2012; 28:427-436. view on PubMed

Dillman AR, Guillermin ML, Lee JH, Kim B, Sternberg PW, Hallem EA. Olfaction shapes host-parasite interactions in parasitic nematodes. Proc Natl Acad Sci USA. 2012; 109:E2324-E2333. view on PubMed

Guillermin ML, Castelletto ML, Hallem EA. Differentiation of carbon dioxide-sensing neurons in Caenorhabditis elegans requires the ETS-5 transcription factor. Genetics. 2011; 189:1327-1339. view on PubMed