Poster Presentation Lorne Infection and Immunity 2022

Australian Aboriginal children with otitis media produce high avidity serum IgG to potential non-typeable Haemophilus influenzae vaccine antigens at lower titres when compared to non-Aboriginal children (#123)

Sharon L Clark 1 2 , Elke Seppanen 2 , Lea-Ann Kirkham 2 3 , Laura Novotny 4 , Lauren Bakaletz 4 , Allan Cripps 5 , Karli Corscadden 2 , Harvey Coates 1 , Shyan Vijayasekaran 1 6 , Peter Richmond 1 2 6 7 , Ruth Thornton 2 3
  1. School of Medicine, The University of Western Australia, Perth, WA, Australia
  2. Wesfarmers Centre of Vaccines & Infectious Disease, Telethon Kids Institute, Perth, WA, Australia
  3. Centre for Child Health Research, The University of Western Australia, Perth, WA, Australia
  4. Centre for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States of America
  5. School of Medicine & Menzies Health Institute, Griffith University, Gold Coast, Queensland, Australia
  6. Perth Children's Hospital, Perth, WA, Australia
  7. Child and adolescent health service, Perth, WA, Australia

Introduction: Australian Aboriginal children have the highest rates of otitis media (middle ear infections) globally. This infection is predominantly caused by the bacteria non-typeable Haemophilus influenzae (NTHi). Previously we demonstrated that Aboriginal children with otitis media have antigen-specific reduction in serum IgG specific for NTHi antigens rsPilA, ChimV4 and Protein D  compared to non-Aboriginal children with and without OM. However there were no difference in serum IgG specific for NTHi antigen Outer Membrane Protein 26 (OMP26) in Aboriginal and non-Aboriginal children.

Objective: To assess natural serum anti-rsPilA, anti-ChimV4, anti-PD and anti-OMP26 IgG avidity in Aboriginal, non-Aboriginal children with otitis media and non-Aboriginal children without otitis media.

Methods: Sera were collected from 77 Aboriginal and 70 non-Aboriginal children with otitis media and 36 non-Aboriginal children without otitis media. Antigen-specific serum IgG avidities were measured using an in-house multiplex immunoassay. IgG avidities were compared between groups using ANOVA.

Results: Aboriginal children with otitis media had similar proportions of high avidity IgG specific for rsPilA, ChimV4 and Protein D compared to non-Aboriginal children with and without otitis media (rsPilA: 56-62%, ChimV4: 50-61% and Protein D: 87-90%; p>0.05). However Aboriginal and non-Aboriginal children with otitis media had a higher proportion of high avidity IgG to OMP26 compared to children without otitis media (73% and 70% vs 61% respectively; p<0.05). IgG avidity had no correlation with IgG titre or age for any antigen.

Conclusion: Australian Aboriginal children produce high avidity IgG to important NTHi antigens rsPilA, ChimV4 and PD, but at reduced levels. Boosting antibody titres through vaccination strategies using these antigens may impact the chronicity and high burden of otitis media in Australian Aboriginal children.