Discovering essential and infection-related genes.

Transposon-based approaches are very powerful for identification of essential and infection-related genes in bacteria, particularly in the context of microbial genomics. We describe recent progress in several of these approaches, and their underlying principles. The essential gene test (EGT) is a transposon-based technique that can rapidly identify a nucleotide sequence from a database as essential or dispensable. Also, variations of in vitro transposon mutagenesis applications, such as genomic analysis and mapping by in vitro transposition (GAMBIT), are described. The development of techniques including PCR-based signature-tagged mutagenesis is now used to find essential virulence genes in different bacterial hosts. These approaches form the basis for the identification of microbial targets in development of novel antimicrobials and vaccines by the biotechnology and pharmaceutical industry.