Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity

Lu, Lu; Zhai, Lina; Ou, Qikun; Sang, Shuli; Cao, Chen; Guan, Yiyan; Mao, Yunyun; Zhai, Yanfang; Li, Kai; Yu, Rui; Wang, Yanchun

doi:10.3390/vaccines13060552

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Open AccessArticle

Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity

by

Lu Lu

^1,†,

Lina Zhai

^2,†,

Qikun Ou

³,

Shuli Sang

¹,

Chen Cao

¹,

Yiyan Guan

¹,

Yunyun Mao

¹,

Yanfang Zhai

¹,

Kai Li

¹,

Rui Yu

^1,*

and

Yanchun Wang

^1,*

¹

Laboratory of Advanced Biotechnology, Beijing Institute of Biotechnology, 20 Dongda Street, Beijing 100071, China

²

Beijing International Science and Technology Cooperation Base for Antiviral Drugs, Beijing Key Laboratory of Environmental and Viral Oncology, College of Chemistry and Life Science, Beijing University of Technology, Beijing 100124, China

³

Department of Cell Biology and Genetics, School of Basic Medical Sciences, Guangxi Medical University, 22 Shuangyong Road, Nanning 530021, China

^*

Authors to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Vaccines 2025, 13(6), 552; https://doi.org/10.3390/vaccines13060552

Submission received: 26 March 2025 / Revised: 11 May 2025 / Accepted: 19 May 2025 / Published: 22 May 2025

(This article belongs to the Section Attenuated/Inactivated/Live and Vectored Vaccines)

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Abstract

Background: Outer Membrane Vesicles (OMVs), nanosized particles derived from Gram-negative bacteria, are promising vaccine carriers due to innate immunogenicity and self-adjuvant properties. Yet the systematic evaluations of OMV-associated toxicity remain limited. Methods: We developed a CRISPR/Cas9-engineered Salmonella enterica serovar Typhimurium ΔmsbB mutant (Mut4_STM) to produce detoxified OMVs (Mut4_OMVs) with enhanced yield. Subcutaneous immunization of BALB/c mice with Mut4_OMVs to evaluate safety, and the adjuvant efficacy was also determined by injecting Mut4_OMVs with Yersinia pestis F1Vmut or Bacillus anthracis PA_D4 antigens, mixing formulation, respectively. Results: Mut4_OMVs showed a 9-fold protein yield increase over wild-type OMVs. While all mice injected with wild-type OMVs died, 100% survival was observed in those receiving Mut4_OMVs. However, dose-dependent pathological alterations became evident in specific organs as the administration dose escalated, such as induced splenic extramedullary hematopoiesis and renal edema. Despite residual toxicity, 2–3 doses of 10 μg Mut4_OMVs elicited antigen-specific antibody titers comparable to aluminum adjuvant controls and superior T-cell immune responses. Conclusion: While Mut4_OMVs retain potent adjuvant activity, their residual toxicity necessitates further biocompatibility optimization for safe vaccine applications.

Keywords: outer membrane vesicles; Salmonella enterica serovar Typhimurium; biocompatibility; adjuvant

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MDPI and ACS Style

Lu, L.; Zhai, L.; Ou, Q.; Sang, S.; Cao, C.; Guan, Y.; Mao, Y.; Zhai, Y.; Li, K.; Yu, R.; et al. Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity. Vaccines 2025, 13, 552. https://doi.org/10.3390/vaccines13060552

AMA Style

Lu L, Zhai L, Ou Q, Sang S, Cao C, Guan Y, Mao Y, Zhai Y, Li K, Yu R, et al. Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity. Vaccines. 2025; 13(6):552. https://doi.org/10.3390/vaccines13060552

Chicago/Turabian Style

Lu, Lu, Lina Zhai, Qikun Ou, Shuli Sang, Chen Cao, Yiyan Guan, Yunyun Mao, Yanfang Zhai, Kai Li, Rui Yu, and et al. 2025. "Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity" Vaccines 13, no. 6: 552. https://doi.org/10.3390/vaccines13060552

APA Style

Lu, L., Zhai, L., Ou, Q., Sang, S., Cao, C., Guan, Y., Mao, Y., Zhai, Y., Li, K., Yu, R., & Wang, Y. (2025). Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity. Vaccines, 13(6), 552. https://doi.org/10.3390/vaccines13060552

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Engineered Outer Membrane Vesicles for Antigen Delivery: Exploratory Study on Adjuvant Activity and Systemic Reactogenicity

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