Hallem, Elissa


Professor, Brain Research Institute

Microbiology, Immunology & Molecular Genetics

Member, Immunity, Microbes & Molecular Pathogenesis GPB Home Area

Molecular, Cellular & Integrative Physiology GPB Home Area

Neuroscience GPB Home Area

Contact Information

Office Phone Number: (310) 825-1778

Office Address:

Los Angeles, CA 90095

Research Interests

The neural basis of parasitic behaviors

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 hosts to infect, 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.


A selected list of publications:

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.
Banerjee N, Hallem E   Sexual Dimorphisms: How sex-shared neurons generate sex-specific behaviors Curr Biol, 2018; 28: R254-R256.
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.
Guillermin ML, Carrillo MA, Hallem EA   A single set of interneurons drives opposite behaviors in C. elegans Curr Biol, 2017; 27: 2630-2639.
Ruiz F, Castelletto ML, Gang SS, Hallem EA   Experience-dependent olfactory behaviors of the parasitic nematode Heligmosomoides polygyrus PLoS Pathog, 2017; 13: e1006709.
Cevallos JA, Okubo RP, Perlman SJ, and Hallem EA   Olfactory preferences of the parasitic nematode Howardula aoronymphium and its insect host Drosophila falleni J Chem Ecol, 2017; 43: 362-373.
Gang SS and Hallem EA   Mechanisms of host seeking by parasitic nematodes Mol Biochem Parasitol, 2016; 208: 23-32.
Rengarajan S and Hallem EA   Olfactory circuits and behaviors of nematodes Curr Opin Neurobiol, 2016; 41: 136-148.
Lee J, Dillman AR, Hallem EA   Temperature-dependent changes in the host-seeking behaviors of parasitic nematodes BMC Biol, 2016; 14: 36.
Carrillo MA and Hallem EA   Gas sensing in nematodes Mol Neurobiol, 2015; 51: 919-931.
Pena JM, Carrillo MA, and Hallem EA   Variation in the susceptibility of Drosophila to different entomopathogenic nematodes Infect Immun, 2015; 83: 1130-8.
Castelletto ML, Gang SS, Okubo RP, Tselikova AA, Nolan TJ, Platzer EG, Lok JB, and Hallem EA   Diverse host-seeking behaviors of skin-penetrating nematodes PLoS Pathog, 2014; 10: e1004305.
Carrillo MA, Guillermin ML, Rengarajan S, Okubo RP, and Hallem EA   O2-sensing neurons control CO2 response in C. elegans J Neurosci, 2013; 33: 9675-83.
Dillman AR, Guillermin ML, Lee J, Kim B, Sternberg PW, and Hallem EA   Olfaction shapes host-parasite interactions in parasitic nematodes Proc Natl Acad Sci USA, 2012; 109: E2324-E2333.
Chaisson KE and Hallem EA   Chemosensory behaviors of parasites Trends Parasitol, 2012; 28: 427-436.
Guillermin ML, Castelletto ML, and Hallem EA   Differentiation of carbon dioxide-sensing neurons in Caenorhabditis elegans requires the ETS-5 transcription factor Genetics, 2011; 189: 1327-39.
Banerjee Navonil, Hallem Elissa A   Decoding Inter-individual Variability in Experience-Dependent Behavioral Plasticity Neuron, 2020; 105(1): 7-9.
Rengarajan Sophie, Yankura Kristen A, Guillermin Manon L, Fung Wendy, Hallem Elissa A   Feeding state sculpts a circuit for sensory valence in Caenorhabditis elegans Proc Natl Acad Sci USA, 2019; 116(5): 1776-1781.
Gang Spencer S, Castelletto Michelle L, Yang Emily, Ruiz Felicitas, Brown Taylor M, Bryant Astra S, Grant Warwick N, Hallem Elissa A   Chemosensory mechanisms of host seeking and infectivity in skin-penetrating nematodes Proc Natl Acad Sci USA, 2020; .
Bryant Astra S, Hallem Elissa A   Terror in the dirt: Sensory determinants of host seeking in soil-transmitted mammalian-parasitic nematodes Int J Parasitol Drugs Drug Resist, 2018; 8(3): 496-510.
Banerjee Navonil, Hallem Elissa A   The role of carbon dioxide in nematode behaviour and physiology Parasitology, 2020; 147(8): 841-854.
Bryant Astra S, Hallem Elissa A   Temperature-dependent behaviors of parasitic helminths Neurosci Lett, 2018; 687(3): 290-303.
Castelletto Michelle L, Gang Spencer S, Hallem Elissa A   Recent advances in functional genomics for parasitic nematodes of mammals J Exp Biol, 2020; 223(Pt Suppl 1): 841-854.