Haemophilus influenzae Protein D antibody suppression in a multi‐component vaccine formulation

• Published in: FEBS open bio 2022-12, Vol.12 (12), p.2191-2202
• Main Authors: Michel, Lea V., Kaur, Ravinder, Gleghorn, Michael L., Holmquist, Melody, Pryharski, Karin, Perdue, Janai, Jones, Seth P., Jackson, Niaya, Pilo, Isabelle, Kasper, Anna, Labbe, Natalie, Pichichero, Michael
• Format: Article
• Language: English
• Subjects: acute otitis media; Aluminum; Animal models; Animals; Antibodies; Antibodies, Bacterial; Antibody response; antibody suppression; Antigenic competition; Antigens; Bacterial Outer Membrane Proteins; Bronchitis; Chronic obstructive pulmonary disease; Column chromatography; Combined vaccines; E coli; Ear diseases; Epitopes; Experiments; Haemophilus influenzae; Haemophilus Vaccines; Immunoglobulin G; Laboratories; Leg; Lymph nodes; Mass spectroscopy; Membrane proteins; Mice; Otitis media; outer membrane protein 26; Outer membrane proteins; Protein D; Proteins; Sinusitis; Vaccines
• ISSN: 2211-5463; 2211-5463
• DOI: 10.1002/2211-5463.13498

Nontypeable Haemophilus influenzae (NTHi) has emerged as a dominant mucosal pathogen causing acute otitis media (AOM) in children, acute sinusitis in children and adults, and acute exacerbations of chronic bronchitis in adults. Consequently, there is an urgent need to develop a vaccine to protect against NTHi infection. A multi‐component vaccine will be desirable to avoid emergence of strains expressing modified proteins allowing vaccine escape. Protein D (PD), outer membrane protein (OMP) 26, and Protein 6 (P6) are leading protein vaccine candidates against NTHi. In pre‐clinical research using mouse models, we found that recombinantly expressed PD, OMP26, and P6 induce robust antibody responses after vaccination as individual vaccines, but when PD and OMP26 were combined into a single vaccine formulation, PD antibody levels were significantly lower. We postulated that PD and OMP26 physiochemically interacted to mask PD antigenic epitopes resulting in the observed effect on antibody response. However, column chromatography and mass spectrometry analysis did not support our hypothesis. We postulated that the effect might be in vivo through the mechanism of protein vaccine immunologic antigenic competition. We found when PD and OMP26 were injected into the same leg or separate legs of mice, so that antigens were immunologically processed at the same or different regional lymph nodes, respectively, antibody levels to PD were significantly lower with same leg vaccination. Different leg vaccination produced PD antibody levels quantitatively similar to vaccination with PD alone. We conclude that mixing PD and OMP26 into a single vaccine formulation requires further formulation studies. When mice are injected with NTHi protein vaccine candidates Protein D or OMP26, there is a robust antibody response to each protein. However, when Protein D and OMP26 are mixed into a single vaccine formulation, mice fail to produce antibody to Protein D. We propose antibody suppression results from a physiochemical interaction or antigenic competition between the two proteins.