Yersinia pestis Plasminogen Activator

Area of Science:

• Microbiology and Infectious Diseases
• Bacteriology
• Pathogen-Host Interactions

Background:

• Yersinia pestis causes plague, a zoonotic disease that can become airborne pneumonia.
• The bacterium employs virulence factors like plasminogen activator (Pla) to evade host innate immunity.
• Pla functions as a protease, adhesin, and invasin, crucial for Y. pestis transmission.

Purpose of the Study:

• To investigate the role of Pla in Y. pestis pathogenesis and host immune evasion.
• To understand the impact of microevolution, specifically the I259T substitution in Pla, on Y. pestis invasiveness.
• To evaluate the potential of Pla as a diagnostic marker and vaccine candidate.

Main Methods:

• Analysis of Pla's proteolytic activity on fibrinolytic and coagulation cascades.
• Investigation of the I259T amino acid substitution's effect on plasminogen activation.
• Assessment of Pla's utility as a diagnostic marker and its role in vaccine development.

Main Results:

• Pla facilitates Y. pestis transmission by manipulating host fibrinolysis and immunity, leading to bacteremia.
• A single amino acid substitution (I259T) in Pla significantly enhances Y. pestis invasiveness by improving plasminogen activation.
• Pla's function in cleaving tissue factor pathway inhibitor (TFPI) remains unclear.
• The pla gene is not exclusive to Y. pestis, diminishing its value as a sole diagnostic marker.
• Pla is ineffective as a subunit vaccine, but its deletion enhances the safety of live Y. pestis vaccines.

Conclusions:

• Pla is a critical virulence factor for Yersinia pestis, mediating host immune evasion and transmission.
• Microevolutionary changes in Pla, like the I259T mutation, can dramatically increase pathogen invasiveness.
• Targeting Pla, particularly through its deletion in attenuated strains, offers a promising strategy for developing safe and effective plague vaccines.