Stages of Infection during the Tripartite Interaction between Xenorhabdus nematophila , Its Nematode Vector, and Insect Hosts
Open Access
- 1 November 2004
- journal article
- Published by American Society for Microbiology in Applied and Environmental Microbiology
- Vol. 70 (11), 6473-6480
- https://doi.org/10.1128/aem.70.11.6473-6480.2004
Abstract
Bacteria of the genus Xenorhabdus are mutually associated with entomopathogenic nematodes of the genus Steinernema and are pathogenic to a broad spectrum of insects. The nematodes act as vectors, transmitting the bacteria to insect larvae, which die within a few days of infection. We characterized the early stages of bacterial infection in the insects by constructing a constitutive green fluorescent protein (GFP)-labeled Xenorhabdus nematophila strain. We injected the GFP-labeled bacteria into insects and monitored infection. We found that the bacteria had an extracellular life cycle in the hemolymph and rapidly colonized the anterior midgut region in Spodoptera littoralis larvae. Electron microscopy showed that the bacteria occupied the extracellular matrix of connective tissues within the muscle layers of the Spodoptera midgut. We confirmed the existence of such a specific infection site in the natural route of infection by infesting Spodoptera littoralis larvae with nematodes harboring GFP-labeled Xenorhabdus . When the infective juvenile (IJ) nematodes reached the insect gut, the bacterial cells were rapidly released from the intestinal vesicle into the nematode intestine. Xenorhabdus began to escape from the anus of the nematodes when IJs were wedged in the insect intestinal wall toward the insect hemolymph. Following their release into the insect hemocoel, GFP-labeled bacteria were found only in the anterior midgut region and hemolymph of Spodoptera larvae. Comparative infection assays conducted with another insect, Locusta migratoria , also showed early bacterial colonization of connective tissues. This work shows that the extracellular matrix acts as a particular colonization site for X. nematophila within insects.Keywords
This publication has 25 references indexed in Scilit:
- Early Colonization Events in the Mutualistic Association between Steinernema carpocapsae Nematodes and Xenorhabdus nematophila BacteriaJournal of Bacteriology, 2003
- The bacterium Xenorhabdus nematophilus depresses nodulation reactions to infection by inhibiting eicosanoid biosynthesis in tobacco hornworms, Manduca sextaArchives of Insect Biochemistry and Physiology, 2003
- Xenorhabdus nematophila (Enterobacteriacea) Secretes a Cation-selective Calcium-independent Porin Which Causes Vacuolation of the Rough Endoplasmic Reticulum and Cell LysisPublished by Elsevier BV ,2003
- Virulence mechanisms.Published by CABI Publishing ,2002
- Xenorhabdus nematophilus as a Model for Host-Bacterium Interactions: rpoS Is Necessary for Mutualism with NematodesJournal of Bacteriology, 2001
- Two Distinct Hemolytic Activities in Xenorhabdus nematophila Are Active against Immunocompetent Insect CellsApplied and Environmental Microbiology, 2001
- The nature of the intestinal vesicle in nematodes of the family steinernematidaeInternational Journal for Parasitology, 1983
- A Neoaplectanid nematode in the larch sawfly Cephalcia lariciphila (Hymenoptera: Pamphiliidae)Annals of Applied Biology, 1981
- Xenorhabdus gen. nov., a Genus of Entomopathogenic, Nematophilic Bacteria of the Family EnterobacteriaceaeInternational Journal of Systematic and Evolutionary Microbiology, 1979
- Mechanism of Buffer Action In SoilsScience, 1927