Outer membrane vesicles: moving within the intricate labyrinth of assays that can predict risks of reactogenicity in...

Area of Science:

• Bacteriology
• Immunology
• Vaccine Development

Background:

• Outer membrane vesicles (OMVs) from Gram-negative bacteria are explored as vaccine platforms due to inherent adjuvant properties and antigen presentation.
• Pathogen-associated molecular patterns (PAMPs), particularly lipid A in OMVs, pose a risk of systemic reactogenicity in humans.

Purpose of the Study:

• To review the historical development and application of assays for evaluating OMV systemic reactogenicity.
• To highlight methods for modulating OMV reactogenicity and immunogenicity for safe human clinical use.

Main Methods:

• Review of historical and current assays including monocyte activation test, rabbit pyrogenicity test, Limulus amebocyte lysate, and human transfectant cells.
• Discussion of chemical and genetic strategies for modulating OMV properties.
• Examination of toxicology studies for predictive risk assessment.

Main Results:

• Development of multiple predictive assays to evaluate OMV systemic reactogenicity.
• Successful modulation of OMV reactogenicity and immunogenicity balance through chemical and genetic means.
• Demonstrated efficacy of assays in assessing risks before clinical use and post-licensure.

Conclusions:

• OMVs are viable vaccine platforms when reactogenicity is effectively managed.
• A suite of validated assays enables the safe clinical development and use of OMVs.
• Ongoing evaluation of OMV-based vaccines ensures continued safety and efficacy.