Use of plant and insect hosts to model bacterial pathogenesis

Abstract

This chapter describes the methodologies used to screen for the identification of previously unknown P aeruginosa virulence-related genes relevant to mammalian pathogenesis. Human bacterial pathogens that infect one or more of the nonmammalian hosts mentioned in the chapter include Pseudomonas aeruginosa , Salmonella typhimurium , Enterococcus , Erwinia spp ., Serratia marcescens , and Proteus vulgaris . The ability of P aeruginosa to infect plants (lettuce and Arabidopsis thaliana ), insects ( Galleria mellonella and Drosophila melanogaster ), nematodes ( Caenorhabditis elegans ), and mice permitted the identification of a large number of “universal” virulence factors and mechanisms of pathogenesis required to cause disease in mammals. The approach and methodologies described in this chapter provide the opportunity to bypass the inherent problems with vertebrate animal models and to perform a genome-wide screen for bacterial virulence factors required for pathogenesis in mammalian hosts. However, to take advantage of this approach, the pathogen of interest should contain virulence factors required for pathogenesis in both invertebrates and mammalian hosts. The chapter describes the methodology used to identify P. aeruginosa “universal” virulence factors using lettuce and Arabidopsis thaliana as well as Galleria mellonella and Drosophila melanogaster as model hosts. It also describes the protocols used to infect Drosophila. melanogaster with Erwinia carotovora using natural modes of infection.