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Updated: May 11, 2026
Evaluation of Host-Pathogen Responses and Vaccine Efficacy in Mice
Published on: February 22, 2019
Comprehensive antigen screening identifies Moraxella catarrhalis proteins that induce protection in a mouse pulmonary
Margarita Smidt1, Patrick Bättig, Suzanne J C Verhaegh
1Intercell AG, Campus Vienna Biocenter 3, Vienna, Austria.
Abstract:
Moraxella catarrhalis is one of the three most common causative bacterial pathogens of otitis media, however no effective vaccine against M. catarrhalis has been developed so far. To identify M. catarrhalis vaccine candidate antigens, we used carefully selected sera from children with otitis media and healthy individuals to screen small-fragment genomic libraries that are expressed to display frame-selected peptides on a bacterial cell surface. This ANTIGENome technology led to the identification of 214 antigens, 23 of which were selected by in vitro or in vivo studies for additional characterization. Eight of the 23 candidates were tested in a Moraxella mouse pulmonary clearance model, and 3 of these antigens induced significantly faster bacterial clearance compared to adjuvant or to the previously characterized antigen OmpCD. The most significant protection data were obtained with the antigen MCR_1416 (Msp22), which was further investigated for its biological function by in vitro studies suggesting that Msp22 is a heme binding protein. This study comprises one of the most exhaustive studies to identify potential vaccine candidate antigens against the bacterial pathogen M. catarrhalis.
Insights
Researchers identified potential vaccine antigens for Moraxella catarrhalis, a common cause of otitis media. One promising antigen, Msp22, demonstrated significant bacterial clearance in a mouse model, suggesting its potential for a new otitis media vaccine.
Area of Science:
- Bacteriology and Immunology
- Vaccine Development
Background:
- Moraxella catarrhalis is a primary bacterial pathogen responsible for otitis media.
- Currently, no effective vaccine exists to prevent M. catarrhalis infections.
Purpose of the Study:
- To identify novel vaccine candidate antigens against Moraxella catarrhalis.
- To evaluate the efficacy of identified antigens in preclinical models.
Main Methods:
- Screening of small-fragment genomic libraries using sera from otitis media patients and healthy individuals.
- Utilized ANTIGENome technology for surface peptide display.
- In vitro and in vivo studies, including a mouse pulmonary clearance model, to characterize candidate antigens.
Main Results:
- Identified 214 potential M. catarrhalis antigens.
- Eight antigens were tested in vivo; three showed significantly enhanced bacterial clearance.
- Antigen MCR_1416 (Msp22) provided the most significant protection and was identified as a heme-binding protein.
Conclusions:
- Msp22 is a highly promising vaccine candidate antigen against Moraxella catarrhalis.
- This study represents a comprehensive effort to discover effective M. catarrhalis vaccine targets.
