Temporal development of the humoral immune response to surface antigens of Moraxella catarrhalis in young infants

The primary Moraxella catarrha/is-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 Hag(385-863), MID(764-913), MID(962-1200), UspA1(557-704) and UspA2(165-318) in 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. (C) 2011 Elsevier Ltd. All rights reserved.