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04_19_05

New Candidate Otitis Media Vaccine

Background: Otitis media (OM), an infection or inflammation of the middle ear, is the most common reason for a sick infant to visit a doctor. OM begins when a viral or bacterial infection spreads from the throat to the middle ear. In recent years, NIDCD intramural scientists developed a detoxified Nontypeable Haemophilus influenzae (NTHi) vaccine against NTHi using lipooligosaccharide (LOS), a sugar-based component found on the surface of bacteria. In addition to NTHi, NIDCD intramural scientists have also been working on a candidate vaccine for another bacterium that causes OM, Moraxella catarrhalis (M. catarrhalis).

Advances: Studies have identified three types of M. catarrhalis LOS (A, B, and C) in individuals with otitis media or other respiratory tract infections. Pre-clinical testing in animal models showed that vaccines against type A LOS were safe and effective, eliciting a significant immune response that inhibited bacterial growth. During the past year, NIDCD intramural scientists have developed new vaccines against type B M. catarrhalis. The current preclinical tests with the newly developed type B vaccines were also shown to be safe and nontoxic in vitro as well as in animal models.

Implications: These type B studies along with the previous type A studies are significant advances towards clinical trials to test these candidate vaccines for safety and efficacy in humans. It is estimated that the two types of vaccines will be able to prevent over 90% of the cases of OM caused by M. catarrhalis. The long term goal is to develop a vaccine that reduces the incidence of OM in children caused by all three major bacterial pathogens: streptococcus
pneumoniae, NTHi, and M. catarrhalis.

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