Cryogenic transmission electron microscopy of recombinant tuberculosis vaccine antigen with anionic liposomes reveals formation of flattened liposomes

• Published in: International journal of nanomedicine Vol. 9; no. Issue 1; pp. 1367 - 1377
• Main Authors: Fox, Christopher B, Mulligan, Sean K, Sung, Joyce, Dowling, Quinton M, Fung, H W Millie, Vedvick, Thomas S, Coler, Rhea N
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01-01-2014; Dove Press; Dove Medical Press
• Subjects: Adjuvants, Immunologic - administration & dosage; Animals; Antigens, Bacterial - chemistry; Antigens, Bacterial - ultrastructure; Cryoelectron Microscopy; Electron microscopy; Humans; Imaging, Three-Dimensional; Liposomes; Liposomes - administration & dosage; Liposomes - chemistry; Nanomedicine; Nanoparticles - administration & dosage; Nanoparticles - chemistry; Original Research; Particle Size; Physiological aspects; Properties; Tuberculosis vaccines; Tuberculosis Vaccines - administration & dosage; Tuberculosis Vaccines - chemistry; Tuberculosis Vaccines - immunology; vaccine adjuvant; cryo-TEM; antigen-adjuvant interactions; vaccine physical characterization; vaccine formulation morphology; 3D tomographic reconstruction; Vaccines, Synthetic - administration & dosage; Vaccines, Synthetic - chemistry; Vaccines, Synthetic - immunology; United States; vaccine physical characterization; vaccine adjuvant; antigen-adjuvant interactions; cryo-TEM; 3D tomographic reconstruction; vaccine formulation morphology
• ISSN: 1178-2013; 1176-9114; 1178-2013
• DOI: 10.2147/IJN.S56582

Development of lipid-based adjuvant formulations to enhance the immunogenicity of recombinant vaccine antigens is a focus of modern vaccine research. Characterizing interactions between vaccine antigens and formulation excipients is important for establishing compatibility between the different components and optimizing vaccine stability and potency. Cryogenic transmission electron microscopy (TEM) is a highly informative analytical technique that may elucidate various aspects of protein- and lipid-based structures, including morphology, size, shape, and phase structure, while avoiding artifacts associated with staining-based TEM. In this work, cryogenic TEM is employed to characterize a recombinant tuberculosis vaccine antigen, an anionic liposome formulation, and antigen-liposome interactions. By performing three-dimensional tomographic reconstruction analysis, the formation of a population of protein-containing flattened liposomes, not present in the control samples, was detected. It is shown that cryogenic TEM provides unique information regarding antigen-liposome interactions not detectable by light-scattering-based methods. Employing a suite of complementary analytical techniques is important to fully characterize interactions between vaccine components.