Identification of vacuoles containing extraintestinal differentiated forms of Legionella pneumophila in colonized Caenorhabditis elegans soil nematodes. Issue 4 (1st July 2015)

• Record Type: Journal Article
• Authors: Hellinga, Jacqueline R.; Garduño, Rafael A.; Kormish, Jay D.; Tanner, Jennifer R.; Khan, Deirdre; Buchko, Kristyn; Jimenez, Celine; Pinette, Mathieu M.; Brassinga, Ann Karen C.
• Is Part Of: MicrobiologyOpen. Volume 4:Issue 4(2015:Aug.)
• Page Start: 660
• Page End: 681
• Publication Date: 2015-07-01
• Subjects: Microbiology -- Periodicals; 579
• DOI: 10.1002/mbo3.271
• Languages: English
• ISSNs: 2045-8827

Abstract

<abstract abstract-type="main" id="mbo3271-abs-0001"> <title>Abstract</title> <p> <italic>Legionella pneumophila</italic>, a causative agent of Legionnaires' disease, is a facultative intracellular parasite of freshwater protozoa. <italic>Legionella pneumophila</italic> features a unique developmental network that involves several developmental forms including the infectious cyst forms. Reservoirs of <italic>L. pneumophila</italic> include natural and man‐made freshwater systems; however, recent studies have shown that isolates of <italic>L. pneumophila</italic> can also be obtained directly from garden potting soil suggesting the presence of an additional reservoir. A previous study employing the metazoan <italic>Caenorhabditis elegans</italic>, a member of the <italic>Rhabditidae</italic> family of free‐living soil nematodes, demonstrated that the intestinal lumen can be colonized with <italic>L. pneumophila</italic>. While both replicative forms and differentiated forms were observed in <italic>C. elegans</italic>, these morphologically distinct forms were initially observed to be restricted to the intestinal lumen. Using live DIC imaging coupled with focused transmission electron microscopy analyses, we report here that <italic>L. pneumophila</italic> is able to invade and establish <italic>Legionella</italic>‐containing vacuoles (LCVs) in the intestinal cells. In addition, LCVs containing replicative and differentiated cyst forms were observed in the pseudocoelomic cavity and gonadal tissue of nematodes colonized with <italic>L. pneumophila</italic>. Furthermore, establishment of LCVs in the gonadal tissue was Dot/Icm dependent and required the presence of the endocytic factor RME‐1 to gain access to maturing oocytes. Our findings are novel as this is the first report, to our knowledge, of extraintestinal LCVs containing <italic>L. pneumophila</italic> cyst forms in <italic>C. elegans</italic> tissues, highlighting the potential of soil‐dwelling nematodes as an alternate environmental reservoir for <italic>L. pneumophila</italic>.</p> </abstract>