The primary Moraxella catarrhalis-specific humoral immune response, and its association with nasopharyngeal colonization, was studied in a cohort of infants from birth to 2 years of age.Results indicated that the levels of antigen-specific IgG, IgA and IgM showed extensive inter-individual variability over time, with IgM and IgA levels to all 9 recombinant domains, from 7 different OMPs, being relatively low throughout the study period. In contrast, the level of antigen-specific IgG was significantly higher for the recombinant domains Hag385-863, MID764-913, MID962-1200, UspA1557-704and UspA2165-318in cord blood compared to 6 months of age (P≤0.001). This was a most likely a consequence of maternal transmission of antigen-specific IgG to newborn babies, possibly indicating a future role for these 3 surface antigens in the development of an effective humoral immune response to M. catarrhalis. Finally, at 2 years of age, the levels of antigen-specific IgG still remained far below that obtained from cord blood samples, indicating that the immune response to M. catarrhalis has not matured at 2 years of age.We provide evidence that a humoral antibody response to OMPs UspA1, UspA2 and Hag/MID may play a role in the immune response to community acquired M. catarrhalis colonization events.

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Erasmus MC: University Medical Center Rotterdam

Verhaegh, S., de Vogel, C., Riesbeck, K., Lafontaine, E., Murphy, T., Verbrugh, H., … Hays, J. (2011). Temporal development of the humoral immune response to surface antigens of Moraxella catarrhalis in young infants. Vaccine, 29(34), 5603–5610. doi:10.1016/j.vaccine.2011.06.019