Approaches for the Inactivation of Yersinia pestis

Introduction: Yersinia pestis is the gram-negative, facultative intracellular bacterium that causes the disease known as plague. Due to the risk for aerosol transmission, a low infectious dose, and the acute and lethal nature of pneumonic plague, research activities with Y. pestis require Biosafety Level 3 (BSL-3) facilities to provide the appropriate safeguards to minimize accidental exposures and environmental release. However, many experimental assays cannot be performed in BSL-3 due to equipment availability, and thus require removal of samples from the BSL-3 laboratory to be completed. Objectives: To remove samples from BSL-3 containment and safely handle them at lower containment requires effective inactivation of any viable organisms from the samples prior to removal. While commonly used inactivation methods have been published for various select agents, there is an absence in the literature of a single source providing detailed examples for inactivation methods for Y. pestis. Our objective here is to provide examples of dose-dependent kill curves for commonly used inactivation approaches against Y. pestis. Methods: Time- and dose-dependent kill curves using heat, methanol, and formaldehyde inactivation methods, and common nucleic acid extraction procedures. Results/Conclusions: We show data demonstrating the complete inactivation of Y. pestis using these methods. While not all-inclusive, this study provides data and examples that can be used by other researchers to develop their own in-house validated inactivation protocols for Y. pestis.