Natural Infection of C. elegans by an Oomycete Reveals a New Pathogen-Specific Immune Response

• Published in: Current biology Vol. 28; no. 4; pp. 640 - 648.e5
• Main Authors: Osman, Guled A., Fasseas, Michael K., Koneru, Sneha L., Essmann, Clara L., Kyrou, Kyros, Srinivasan, Mandayam A., Zhang, Gaotian, Sarkies, Peter, Félix, Marie-Anne, Barkoulas, Michalis
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 19-02-2018; Elsevier
• Subjects: Animal biology; Animals; C. elegans; Caenorhabditis elegans - genetics; Caenorhabditis elegans - immunology; Caenorhabditis elegans - microbiology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - immunology; chitinase-like; chitolectins; cuticle; Gene Expression Regulation - immunology; Genetics; Host-Pathogen Interactions - genetics; Host-Pathogen Interactions - immunology; hypodermis; Immunity, Innate - genetics; Immunology; Innate immunity; Life Sciences; Microbiology and Parasitology; Multigene Family - immunology; Myzocytiopsis humicola; oomycete; Oomycetes - physiology; Parasitology; Protistology; pseudoenzymes; oomycete; innate immunity; Myzocytiopsis humicola; chitolectins; cuticle; pseudoenzymes; C. elegans; hypodermis; chitinase-like
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2018.01.029

In its natural habitat, the nematode Caenorhabditis elegans encounters a plethora of other organisms, including many that are pathogenic [1, 2]. The study of interactions between C. elegans and various pathogens has contributed to characterizing key mechanisms of innate immunity [2–4]. However, how C. elegans recognizes different pathogens to mount pathogen-specific immune responses remains still largely unknown [3, 5–8]. Expanding the range of known C. elegans-infecting pathogens and characterizing novel pathogen-specific immune responses are key steps toward answering this question. We report here that the oomycete Myzocytiopsis humicola is a natural pathogen of C. elegans, and we describe its infection strategy. We identify a new host immune response to pathogen exposure that involves induction of members of a previously uncharacterized gene family encoding chitinase-like (CHIL) proteins. We demonstrate that this response is highly specific against M. humicola and antagonizes the infection. We propose that CHIL proteins may diminish the ability of the oomycete to infect by hindering pathogen attachment to the host cuticle. This work expands our knowledge of natural eukaryotic pathogens of C. elegans and introduces a new pathosystem to address how animal hosts recognize and respond to oomycete infections.
•Myzocytiopsis humicola is a natural oomycete pathogen of C. elegans•We set up a system to study animal infecting oomycetes using C. elegans as a host•Chitinase-like genes are specifically induced in response to M. humicola exposure•CHIL proteins protect the host by hindering pathogen attachment to the cuticle
Osman et al. expand the list of known eukaryotic pathogens of C. elegans by describing its natural infection by an oomycete. They find that the immune response mounted by the nematode against the pathogen includes the specific induction of some previously uncharacterised chitinase-like proteins.