Genomic Analysis of Immune Response against Vibrio cholerae Hemolysin in Caenorhabditis elegans

Jeong H. Lee,Surasri N. Sahu,Hediye Nese Cinar,Joseph E. LeClerc,Isha Patel,Serdar Bozdag,Jada Lewis

doi:10.1371/journal.pone.0038200

Abstract

Vibrio cholerae cytolysin (VCC) is among the accessory V. cholerae virulence factors that may contribute to disease pathogenesis in humans. VCC, encoded by hlyA gene, belongs to the most common class of bacterial toxins, known as pore-forming toxins (PFTs). V. cholerae infects and kills Caenorhabditis elegans via cholerae toxin independent manner. VCC is required for the lethality, growth retardation and intestinal cell vacuolation during the infection. However, little is known about the host gene expression responses against VCC. To address this question we performed a microarray study in C. elegans exposed to V. cholerae strains with intact and deleted hlyA genes.Many of the VCC regulated genes identified, including C-type lectins, Prion-like (glutamine [Q]/asparagine [N]-rich)-domain containing genes, genes regulated by insulin/IGF-1-mediated signaling (IIS) pathway, were previously reported as mediators of innate immune response against other bacteria in C. elegans. Protective function of the subset of the genes up-regulated by VCC was confirmed using RNAi. By means of a machine learning algorithm called FastMEDUSA, we identified several putative VCC induced immune regulatory transcriptional factors and transcription factor binding motifs. Our results suggest that VCC is a major virulence factor, which induces a wide variety of immune response- related genes during V. cholerae infection in C. elegans.

Highlights

V. cholerae cytolysin (VCC) is among the accessory V. cholerae virulence factors that may contribute to the sporadic form of diarrheal disease pathogenesis
We performed a microarray study of C. elegans, which was exposed to V. cholerae strains with intact and deleted hlyA genes using Affymetrix C. elegans arrays
Gene expression in worms exposed to Wild type O1 el tor V. cholerae strain E7946 was compared with gene expression in worms exposed to the hlyA deletion mutant of E7946

Summary

Introduction

V. cholerae cytolysin (VCC) is among the accessory V. cholerae virulence factors that may contribute to the sporadic form of diarrheal disease pathogenesis. Many of the differentially expressed genes previously reported as mediators of innate immune response against other bacteria in C. elegans, suggesting that C. elegans uses common and specific mechanisms against V.cholerae and these defenses are induced by VCC. Immune response function of the subset of the differentially expressed genes against V. cholerae infection was confirmed using RNAi. Using a machine learning algorithm called

Results

Conclusion