[Yersinia pestis superoxide dismutase]

Area of Science:

• Microbiology
• Immunology
• Enzymology

Background:

• Superoxide dismutases (SODs) are critical enzymes for cellular defense against oxidative stress.
• Yersinia pestis, the causative agent of plague, possesses SODs that may play a role in its virulence and survival.
• Understanding Y. pestis SODs is important for developing effective countermeasures against plague.

Purpose of the Study:

• To identify and characterize superoxide dismutases in Yersinia pestis EV cells.
• To investigate the properties and regulation of Y. pestis superoxide dismutases.
• To evaluate the immunogenicity and protective efficacy of Y. pestis superoxide dismutase.

Main Methods:

• Enzyme identification and molecular weight determination.
• Analysis of antigenic specificity, thermal resistance, and inhibitor sensitivity.
• Investigation of thermoinducible activity and release into culture medium.
• Humoral response assessment in patients and immunization studies in guinea pigs.

Main Results:

• Two superoxide dismutases (65-67 kD and 200 kD) were identified in Y. pestis EV cells.
• These enzymes exhibited differences in antigenic specificity, heat resistance, and inhibitor susceptibility.
• Superoxide dismutase activity was thermoinducible and not plasmid-dependent, with enzymes released into the medium.
• A humoral response to high molecular-weight SOD was observed in patients vaccinated with live plague vaccine.
• Immunization of guinea pigs with purified high molecular-weight SOD conferred specific protection against plague.

Conclusions:

• Yersinia pestis possesses distinct superoxide dismutases with unique characteristics.
• High molecular-weight superoxide dismutase from Y. pestis is immunogenic and provides protective immunity.
• This high molecular-weight superoxide dismutase is a promising candidate for plague vaccine development.