New Tools for Virulence Gene Discovery

Abstract

Early forays into identifying virulence genes used the basic tools of bacterial genetics: mutation and complementation. The fundamental biology of some host-pathogen interactions can limit the ability to apply signature-tagged mutagenesis (STM) and related approaches. One of the most versatile tools to probe host-pathogen interactions is the green fluorescent protein (GFP). Differential fluorescence induction (DFI)-based screens have yielded a high proportion of virulence genes relative to housekeeping genes. Part of this success results not from any particular advantage of the DFI technique per se but from a principle that is important when designing any screen based on analysis of differential expression, be it DNA microarrays or in vivo expression technology (IVET). Caenorhabditis elegans is one of the prevalent model systems used to study the development of multicellular organisms. The availability of whole genomic sequences presents another method of virulence gene discovery: bioinformatics. This chapter outlines a variety of approaches used to identify candidate virulence genes. The genome sequence of every major pathogen (and most minor ones) is or will soon be available. These genomic sequences, augmented by the gene discovery methods described in the chapter, should permit the discovery of novel virulence genes at an unprecedented pace.