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Updated: Mar 29, 2026
Dissection of the Auditory Bulla in Postnatal Mice: Isolation of the Middle Ear Bones and Histological Analysis
Published on: January 4, 2017
A new model for non-typeable Haemophilus influenzae middle ear infection in the Junbo mutant mouse
Derek Hood1, Richard Moxon2, Tom Purnell1
1MRC Mammalian Genetics Unit, MRC Harwell, Didcot, Oxford, OX11 0RD, UK.
Abstract:
Acute otitis media, inflammation of the middle ear, is the most common bacterial infection in children and, as a consequence, is the most common reason for antimicrobial prescription to this age group. There is currently no effective vaccine for the principal pathogen involved, non-typeable Haemophilus influenzae (NTHi). The most frequently used and widely accepted experimental animal model of middle ear infection is in chinchillas, but mice and gerbils have also been used. We have established a robust model of middle ear infection by NTHi in the Junbo mouse, a mutant mouse line that spontaneously develops chronic middle ear inflammation in specific pathogen-free conditions. The heterozygote Junbo mouse (Jbo/+) bears a mutation in a gene (Evi1, also known as Mecom) that plays a role in host innate immune regulation; pre-existing middle ear inflammation promotes NTHi middle ear infection. A single intranasal inoculation with NTHi produces high rates (up to 90%) of middle ear infection and bacterial titres (10(4)-10(5) colony-forming units/µl) in bulla fluids. Bacteria are cleared from the majority of middle ears between day 21 and 35 post-inoculation but remain in approximately 20% of middle ears at least up to day 56 post-infection. The expression of Toll-like receptor-dependent response cytokine genes is elevated in the middle ear of the Jbo/+ mouse following NTHi infection. The translational potential of the Junbo model for studying antimicrobial intervention regimens was shown using a 3 day course of azithromycin to clear NTHi infection, and its potential use in vaccine development studies was shown by demonstrating protection in mice immunized with killed homologous, but not heterologous, NTHi bacteria.
Insights
A new Junbo mouse model effectively mimics childhood middle ear infections caused by non-typeable Haemophilus influenzae (NTHi). This model aids in testing new vaccines and antimicrobial treatments for NTHi otitis media.
Area of Science:
- Microbiology
- Immunology
- Otolaryngology
Background:
- Acute otitis media is a common childhood infection and a primary reason for antibiotic prescriptions.
- Non-typeable Haemophilus influenzae (NTHi) is a key pathogen in otitis media, lacking an effective vaccine.
- Existing animal models for middle ear infections have limitations.
Purpose of the Study:
- To establish and validate a robust mouse model for NTHi-induced otitis media.
- To assess the translational potential of this model for evaluating antimicrobial therapies and vaccine efficacy.
Main Methods:
- Utilized the Junbo mouse model (Jbo/+), which exhibits spontaneous chronic middle ear inflammation.
- Administered a single intranasal inoculation of NTHi to induce middle ear infections.
- Monitored infection rates, bacterial titers, and host immune responses (cytokine gene expression).
- Evaluated the efficacy of azithromycin treatment and a killed NTHi vaccine in the model.
Main Results:
- The Junbo mouse model demonstrated high infection rates (up to 90%) and bacterial loads following NTHi inoculation.
- Bacterial clearance occurred in most mice between days 21-35, with persistence in some up to day 56.
- Elevated expression of Toll-like receptor-dependent cytokine genes was observed in infected middle ears.
- Azithromycin treatment successfully cleared NTHi, and immunization with killed homologous NTHi provided protection.
Conclusions:
- The Junbo mouse model is a viable and robust platform for studying NTHi middle ear infections.
- This model shows significant translational potential for preclinical testing of antimicrobial regimens and vaccine candidates against NTHi otitis media.
