The reverse approach to vaccine development takes advantage of the genome sequence of the pathogen. The genome sequence provides at once a catalogue of virtually all protein antigens that the pathogen can express at any time. The reverse vaccinology begins with bioinformatics analysis to identify antigens in silico that are then experimentally tested. This sequence is a reversal of the standard work flow in which analysis requiring culturing the organism comes initially and bioinformatics analysis subsequently. This approach, used originally against meningococcus, lets fast identification of candidate vaccines and provides new solutions for those vaccines which have been difficult or impossible to develop (Rappuoli 2001; Sette and Rappuoli 2010).