Bubonic plague vaccine
The bubonic plague vaccine is designed to prevent infection from the bacterium Yersinia pestis, the causative agent of plague. The first effective vaccine was developed by Waldemar Mordecai Haffkine in 1897 during an epidemic in Bombay, India. While the Haffkine vaccine reduced mortality by 20 to 30 percent, it had significant side effects and did not provide complete protection. Later vaccines, developed in the 1930s using live attenuated strains of Yersinia pestis, were adopted by various countries but similarly posed safety concerns and required multiple booster shots.
Due to the limitations of these early vaccines, new generation vaccines are currently under development, focusing on subunit and attenuated forms of the bacteria. These newer vaccines aim to provide better protection, including against pneumonic plague, which presents greater treatment challenges. Researchers are also exploring other vaccine types, such as dual anthrax/plague nanoparticle vaccines and DNA vaccines. With some strains of plague showing antibiotic resistance, the advancement of effective vaccines remains crucial in managing and preventing the disease.
Subject Terms
Bubonic plague vaccine
Definition
The bubonic plague vaccine prevents infection with the bacterium Yersinia pestis, which causes plague.
Early Developments
In 1897, Waldemar Mordecai Haffkine developed the first effective plague vaccine, a bacterial suspension of killed Y. pestis injected as a preventive, during a plague epidemic in Bombay (now Mumbai), India. The Haffkine vaccine was not perfect, but it reduced plague mortality by 20 to 30 percent. However, it had numerous unpleasant side effects.
In the 1930s, scientists in Madagascar and Java produced a vaccine based on a live attenuated strain of Y. pestis. Both vaccines continued to be used; the United States relied on the Haffkine vaccine, while the French, Russians, and Chinese relied on the attenuated strain for vaccination.
Both the Haffkine and the EV (from the initials of the person from whose body it was isolated) attenuated vaccines have problems. Neither provides full protection against bubonic nor pneumonic plague. Both have unpleasant side effects (and can be fatal), although recent administration techniques have decreased these side effects. Both require several booster shots to be effective.
US health officials discontinued administering the plague vaccine in 1999 except in special cases. The EV vaccine has shown a potential to be lethal in laboratory animals, calling its use into question in countries that had adopted it.
New Generation Vaccines
Because of the difficulties with both early vaccines, scientists have been trying to find vaccines that overcome the health problems of the earlier vaccines, are easier to administer, and convey immunity against pneumonic plague, too. Because pneumonic plague (unlike bubonic plague) is difficult to treat with antibiotics, scientists consider the development of a vaccine that is effective against both types of plague essential.
Most work has concentrated on developing subunit and live attenuated vaccines. A subunit vaccine (using subunits of the bacteria) in development was effective against both bubonic and pneumonic plague. This vaccine is based on the F1 and V antigens, which induce protective responses in persons. When combined, these proteins have shown an additional protective effect.
Other work focuses on developing a vaccine using attenuated forms of the bacteria. This vaccine, essentially a fourth-generation form, is expected to provide greater protection against Y. pestis than the subunit form.
In the mid-2020s, both subunit and live attenuated vaccines effective for protecting against bubonic and pneumonic plague were still in development, as is the one using the attenuated forms of bacteria. Continued research and clinical trials must be conducted before these vaccines are approved. Other types of vaccines are also being developed. These include a dual anthrax/plague nanoparticle vaccine, multivalent vaccines, and DNA vaccines.
Impact
Plague vaccines have always been considered effective in dealing with the plague because they prevent the disease rather than, like antibiotics, simply treat it. The first and second-generation vaccines helped to reduce plague deaths, but they had several problems, and their use has largely been discontinued. Finally, because some strains of plague have developed antibiotic resistance, it is crucial to develop newer and more effective forms of plague vaccine.
Bibliography
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Zhang, Wei, et al. "Complete Protection Against Yersinia Pestis in BALB/C Mouse Model Elicited by Immunization With Inhalable Formulations of RF1-V10 Fusion Protein via Aerosolized Intratracheal Inoculation." Frontiers in Immunology, vol. 13, 2022, p. 793382, doi.org/10.3389/fimmu.2022.793382. Accessed 27 Sept. 2024.