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Updated: Jun 21, 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
Biophysical and stabilization studies of the Chlamydia trachomatis mouse pneumonitis major outer membrane protein
Sumin Cai1, Feng He, Hardeep S Samra
1Laboratory for Macromolecular and Vaccine Stabilization, Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66047, USA.
Abstract:
Native Chlamydia trachomatis mouse pneumonitis major outer membrane protein (nMOMP) induces effective protection against genital infection in a mouse challenge model. The conformation of nMOMP is crucial to confer this protective immunity. To achieve a better understanding of the conformational behavior and stability of nMOMP, a number of spectroscopic techniques are employed to characterize the secondary structure (circular dichroism), tertiary structure (intrinsic fluorescence) and aggregation properties (static light scattering and optical density) as a function of pH (3-8) and temperature (10-87.5 degrees C). The data are summarized in an empirical phase diagram (EPD) which demonstrates that the thermal stability of nMOMP is strongly pH-dependent. Three distinctive regions are seen in the EPD. Below the major thermal transition regions, nMOMP remains in its native conformation over the pH range of 3-8. Above the thermal transitions, nMOMP appears in two different structurally altered states; one at pH 3-5 and the other at pH 6-8. The EPD shows that the highest thermal transition point ( approximately 65 degrees C) of nMOMP is near pH 6. Several potential excipients such as arginine, sodium citrate, Brij 35, sucrose and guanidine are also selected to evaluate their effects on the stability of nMOMP. These particular compounds increase the aggregation onset temperature of nMOMP by more than 10(omicron)C, without affecting its secondary and tertiary structure. These results should help formulate a vaccine using a recombinant MOMP.
Insights
Native Chlamydia trachomatis mouse pneumonitis major outer membrane protein (nMOMP) is conformationally stable across a wide pH range. Excipients enhance nMOMP stability, aiding vaccine formulation.
Area of Science:
- Immunology
- Structural Biology
- Biochemistry
Background:
- The major outer membrane protein (MOMP) of Chlamydia trachomatis is essential for protection against genital infections.
- The conformational integrity of nMOMP is critical for its immunoprotective properties.
- Understanding nMOMP's conformational behavior and stability is key for vaccine development.
Purpose of the Study:
- To investigate the conformational stability of native Chlamydia trachomatis mouse pneumonitis major outer membrane protein (nMOMP) under varying pH and temperature conditions.
- To characterize the secondary and tertiary structures and aggregation properties of nMOMP.
- To evaluate the impact of potential excipients on nMOMP stability.
Main Methods:
- Spectroscopic techniques including circular dichroism (CD) for secondary structure, intrinsic fluorescence for tertiary structure, and static light scattering/optical density for aggregation.
- Analysis across a pH range of 3-8 and temperatures from 10-87.5°C.
- Empirical phase diagram (EPD) construction to visualize stability regions.
- Assessment of excipient effects (arginine, sodium citrate, Brij 35, sucrose, guanidine).
Main Results:
- nMOMP maintains its native conformation between pH 3-8 below thermal transition temperatures.
- Above thermal transitions, nMOMP adopts altered states at pH 3-5 and pH 6-8.
- The highest thermal transition point (approx. 65°C) occurs near pH 6.
- Selected excipients increased the aggregation onset temperature by over 10°C without altering nMOMP's secondary or tertiary structure.
Conclusions:
- The thermal stability of nMOMP is significantly influenced by pH, with optimal stability near pH 6.
- Excipients can enhance nMOMP stability, offering a promising avenue for vaccine formulation.
- These findings provide crucial data for developing effective vaccines based on recombinant MOMP.
