Technological advances together with a better understanding of the molecular biology of
infectious microorganisms are creating exciting possibilities for a new generation of
replicating vaccines. Historically live vaccines have been either directly derived from a
natural source or attenuated by empirical approaches using serial passages and host cell
adaptation. Currently we are witnessing a quantum leap in our technological capabilities to
specifically modify the genetic make-up of viruses and bacteria making it possible to generate
improved live vaccines and to develop completely new types of replicating vaccines such as
vectored vaccines single-round infectious vaccines and replicon vaccines. This book highlights
some of the most exciting recent developments towards a new generation of replicating vaccines.
