Conservation of Salmonella Infection Mechanisms in Plants and Animals

Adam Schikora,Pierrette Menanteau,Philippe Velge,Theodora Nilau,Heribert Hirt,Isabelle Virlogeux-Payant,Amélie Charrier,Ana V Garcia,Sandra Pelletier,Eduardo Bueso,Manuela Baccarini

doi:10.1371/journal.pone.0024112

Adam Schikora, Pierrette Menanteau + Show 9 more

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https://doi.org/10.1371/journal.pone.0024112

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Abstract

Salmonella virulence in animals depends on effectors injected by Type III Secretion Systems (T3SSs). In this report we demonstrate that Salmonella mutants that are unable to deliver effectors are also compromised in infection of Arabidopsis thaliana plants. Transcriptome analysis revealed that in contrast to wild type bacteria, T3SS mutants of Salmonella are compromised in suppressing highly conserved Arabidopsis genes that play a prominent role during Salmonella infection of animals. We also found that Salmonella originating from infected plants are equally virulent for human cells and mice. These results indicate a high degree of conservation in the defense and infection mechanism of animal and plant hosts during Salmonella infection.

Highlights

Different serotypes of Salmonella, together with Escherichia coli O157:H7 and Campylobacter spp. are the most prominent causes of food poisoning worldwide [1]
Statistical analysis of variance in the recovered populations using F-test suggests that the rates at which plant- and LB-originated bacteria proliferate in epithelial cells are comparable (p$0.05) (Fig. 1A, Supplementary Fig. S1B)
Salmonella from plants retain virulence toward animals Using epithelial cells and in vivo mice assays, we demonstrate in this report, that Salmonella originating from Arabidopsis leaves are as virulent as Salmonella grown in standard media (Fig. 1)

Summary

Introduction

Different serotypes of Salmonella, together with Escherichia coli O157:H7 and Campylobacter spp. are the most prominent causes of food poisoning worldwide [1]. Studies of the infection mechanisms in animals have shown that Salmonella actively remodels the host cell’s physiology and architecture, and suppresses the host immune system by injecting a cocktail of effectors delivered by Type III Secretion System (T3SS). Typhimurium) has two distinct T3SSs, T3SS-1 and T3SS-2, encoded by the Salmonella Pathogenicity Islands (SPI) SPI-1 and SPI-2 respectively [3,4]. T3SS-1 secretes at least 14 proteins of which 6 were shown to interact with the host signaling cascades and the cytoskeleton. T3SS-2 secretes at least 19 Salmonella enterica specific effector proteins that are involved in survival and multiplication within the Salmonella containing vesicle (SCV) [5,6]. Some of the effectors can be translocated by both T3SSs, reviewed in [7]

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