Development of a Virosomal RSV Vaccine Containing 3D-PHAD® Adjuvant: Formulation, Composition, and Long-Term...

Area of Science:

• Vaccinology
• Virology
• Nanotechnology

Background:

• Respiratory Syncytial Virus (RSV) is a major cause of respiratory illness in infants and older adults.
• Current RSV vaccines are limited, necessitating the development of novel vaccine candidates.
• Virosomes are promising vaccine delivery systems that can incorporate viral antigens and adjuvants.

Purpose of the Study:

• To characterize virosomes formulated with a synthetic monophosphoryl lipid A, 3D-PHAD® adjuvant, for potential use as RSV vaccines.
• To evaluate the stability and immunogenicity of these adjuvanted virosomes in preclinical development.

Main Methods:

• Virosomes were prepared using different methods involving lipid films, viral membranes, and the adjuvant 3D-PHAD®.
• Characterization included cryo-electron microscopy, single particle tracking (SPT), and dynamic light scattering.
• Stability was assessed over 300 days, and antibody titers were measured.

Main Results:

• Virosomes incorporated viral glycoproteins G and F, along with lipids and the 3D-PHAD® adjuvant.
• Single particle tracking revealed stable virosome size, while dynamic light scattering indicated small aggregates.
• Enhanced 3D-PHAD® incorporation was achieved using DCPC-solubilized or DMSO-dissolved adjuvant, leading to comparable antibody titers.

Conclusions:

• Stable 3D-PHAD® adjuvanted RSV virosomes can be successfully formulated.
• These findings support the further development of virosome-based RSV vaccines.