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Updated: Jun 25, 2026
Cell-Free Scaled Production and Adjuvant Addition to a Recombinant Major Outer Membrane Protein from Chlamydia muridarum for Vaccine Development
Published on: March 16, 2022
IFNγ-producing iNKTs restrict a live-attenuated chlamydia oral vaccine in the large intestine
Ahmed Mohamed Abdelsalam1, Yi Wu1, Mitchell Kronenberg2
1Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
Abstract:
Chlamydia muridarum continuously sheds live organisms and persists in the large intestine following intracolonic inoculation, while the live-attenuated chlamydia oral vaccine intrOv, an IFNγ-susceptible mutant of C. muridarum, fails to do so. IFNγ delivered by group 3 innate lymphoid cells (ILC3s) have been shown to block intrOv shedding. We now report that mice deficient in lymphocytes but competent in ILCs allowed intrOv to persist, revealing a critical role of lymphocytes for preventing intrOv persistence. The responsible lymphocyte subsets are natural killer T cells (NKTs), as mice deficient in either CD1d or β2m permitted intrOv to persist. We further narrowed the responsible cells to invariant NKTs (iNKTs) that produce IFNγ, as mice deficient in TCRα J18 segment (Traj18), T-bet, or IFNγ failed to prevent intrOv persistence. Consistently, intrOv induced IFNγ+iNKTs, and wild-type iNKTs prevented intrOv persistence in mice deficient in either lymphocytes or IFNγ. Thus, IFNγ+iNKTs are both necessary and sufficient for preventing intrOv persistence, while IFNγ+ILC3s are for blocking intrOv shedding, revealing a division of labor between IFNγ+iNKTs and IFNγ+ILC3s in regulating the interaction of the obligate intracellular Chlamydia with host mucosal tissue. The information is also essential for improving the safety and efficacy of intrOv as an oral vaccine.
Insights
Invariant natural killer T cells (iNKTs) producing IFNγ are crucial for preventing oral chlamydia vaccine persistence. Group 3 innate lymphoid cells (ILC3s) block vaccine shedding, revealing distinct roles in host-pathogen interactions.
Area of Science:
- Immunology
- Microbiology
- Vaccinology
Background:
- Chlamydia muridarum persists in the gut after inoculation.
- A live-attenuated oral vaccine (intrOv) normally fails to persist.
- IFNγ from group 3 innate lymphoid cells (ILC3s) blocks intrOv shedding.
Purpose of the Study:
- To identify lymphocytes critical for preventing oral chlamydia vaccine (intrOv) persistence.
- To elucidate the roles of specific immune cells in regulating chlamydial interactions with host tissues.
Main Methods:
- Used genetically modified mice lacking specific lymphocyte populations (e.g., CD1d, β2m, Traj18, T-bet deficient mice).
- Assessed intrOv persistence and shedding in these mouse models.
- Quantified interferon-gamma (IFNγ) production by specific immune cell subsets.
Main Results:
- Lymphocytes, specifically invariant natural killer T cells (iNKTs), are essential for preventing intrOv persistence.
- IFNγ-producing iNKTs were both necessary and sufficient to prevent intrOv persistence.
- IFNγ-producing ILC3s were responsible for blocking intrOv shedding, demonstrating a division of labor.
Conclusions:
- IFNγ+ iNKTs play a critical role in preventing oral chlamydia vaccine persistence.
- IFNγ+ ILC3s are key in blocking vaccine shedding.
- Understanding these distinct immune cell functions is vital for improving oral chlamydia vaccine safety and efficacy.
