Abstract
Three great plague pandemics caused by the gram-negative bacterium Yersinia pestis have killed nearly 200 million people and it has been linked to biowarfare in the past. Plague is endemic in many parts of the world. In addition, the risk of plague as a bioweapon has prompted increased research to develop plague vaccines against this disease. Injectable subunit vaccines are being developed in the United States and United Kingdom. However, the live attenuated Y. pestis-EV NIIEG strain has been used as a vaccine for more than 70 years in the former Soviet Union and in some parts of Asia and provides a high degree of efficacy against plague. This vaccine has not gained general acceptance because of safety concerns. In recent years, modern molecular biological techniques have been applied to Y. pestis to construct strains with specific defined mutations designed to create safe, immunogenic vaccines with potential for use in humans and as bait vaccines to reduce the load of Y. pestis in the environment. In addition, a number of live, vectored vaccines have been reported using attenuated viral vectors or attenuated Salmonella strains to deliver plague antigens. Here we summarize the progress of live attenuated vaccines against plagu.
Highlights
Yersinia pestis, the causative agent of plague, is an aerobic, non-motile, gram-negative bacillus belonging to the family Enterobacteriaceae
Y. pestis cells spread from the site of the infected flea bite to the regional lymph nodes, grow to high numbers causing the formation of a bubo, and spill into the blood-stream where bacteria are removed in the liver and spleen
In humans bubonic plague can develop into an infection of the lung; this can lead to aerosol transmission [2, 6]
Summary
The causative agent of plague, is an aerobic, non-motile, gram-negative bacillus belonging to the family Enterobacteriaceae. Large reservoirs of Y. pestis still exist on all major inhabited continents, except Australia [2] and it still remains a serious public health threat in those regions [2,3]. Y. pestis cells spread from the site of the infected flea bite to the regional lymph nodes, grow to high numbers causing the formation of a bubo, and spill into the blood-stream where bacteria are removed in the liver and spleen. In addition to the potential for natural infections, Y. pestis is considered to be among the top five potential biological weapons [7]. Other evidence suggests that Y. pestis was being developed for potential biological warfare use in the former Soviet Union [7,8,9,10,11] as well as in the US and in Great Britain.
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