Yersinia pestis is the etiological agent of bubonic and
pneumonic plague, diseases which have caused over 200 milllion human deaths in the past.
Plague still occurs throughout the world today, though for reasons that are not fully understood pandemics of disease do not develop from these outbreaks.
Antibiotic treatment of
bubonic plague is usually effective, but
pneumonic plague is difficult to treat and even with
antibiotic therapy death often results. A killed whole cell
plague vaccine has been used in the past, but recent studies in animals have shown that this
vaccine offers poor protection against pneumonic disease. A live
attenuated vaccine is also available. Whilst this
vaccine is effective, it retains some virulence and in most countries it is not considered to be suitable for use in humans. We review here work to develop improved sub-unit and live
attenuated vaccines against
plague. A sub-unit
vaccine based on the F1- and V-
antigens is highly effective against both bubonic and
pneumonic plague, when tested in animal models of disease. This
vaccine has been used to explore the utility of different intranasal and oral delivery systems, based on the microencapsulation or Salmonella delivery of sub-units.