Objective:

To compare the protective effect of HRSV prefusion protein (Pre-F) with different adjuvants in BALB/c mice.

Approach:

• Experimental Groups: BALB/c mice were divided into three experimental groups: Pre-F+AlOH+CpG, Pre-F+AlOH, and Pre-F+BFA03.
• Control Groups: Three adjuvant control groups were established: AlOH+CpG, AlOH, and BFA03.
• Immunization and Measurement: Mice received two intramuscular immunizations, followed by measurement of serum neutralizing antibody titers and quantification of IFN-γ- and IL-4-secreting lymphocytes.
• Post-Challenge Monitoring: After viral challenge, body weight changes, lung viral loads, and lung pathological damage were assessed.

Key Findings:

• Mice in experimental groups showed high neutralizing antibody titers and increased IFN-γ- and IL-4-secreting lymphocytes.
• Mice immunized with Pre-F+BFA03 had the highest neutralizing antibody titre (1716) and the lowest lung viral load.
• Pre-F+AlOH group exhibited the most severe lung damage and highest viral load.
• Pre-F+AlOH+CpG group had less lung damage compared to Pre-F+AlOH, with comparable immune response to BFA03.

Interpretation:

Pre-F protein combined with AlOH+CpG or BFA03 adjuvant provided similar protection in mice, both superior to AlOH adjuvant.

Limitations:

• Study conducted only in BALB/c mice, which may limit generalizability to other populations.
• Long-term efficacy and safety of the adjuvants and vaccine formulation were not assessed.

Conclusion:

The study provides a reference for adjuvant selection and formulation strategies in HRSV Pre-F protein vaccine development.