Project Title: Measuring Epitope-Specific Mucosal Antibodies Against Influenza to Predict Immunity and Develop Improved Vaccines
We have developed an influenza antigen microarray containing over 300 influenza antigens, including hemagglutinin (HA) antigens across all subtypes both as whole molecules and head groups only. The antigens are obtained commercially as lyophilized purified proteins expressed in baculovirus and printed onto nitrocellulose-coated slides using a microarray printer using previously described methods (Davies DH et al., PNAS, 2005). We have probed sera collected from a prospective cohort of college students who were followed for development of influenza infection. From this cohort, we demonstrated that individuals who subsequently become infected with influenza have decreased subtype-specific IgA antibodies at baseline compared to individuals from the same population who do not become infected, but baseline subtype- specific IgG antibodies are not significantly different (Figure 1). As a pilot experiment, we used the influenza antigen microarray to measure mucosal immunity in volunteers by probing nasopharyngeal swab eluates, with representative data shown for an individual patient that demonstrates technical feasibility with good correlation between serum and mucosal antibodies (Figure 2). Based on these data, we hypothesize that the specificity of host mucosal antibodies for circulating influenza virus determines susceptibility to clinical infection and virus shedding, and that identifying the targets for mucosal antibodies that correlate with clinical immunity can inform the design of novel immunogens for candidate universal influenza vaccines. To test this hypothesis, we have formulated the following specific aims. Aim 1. To correlate host mucosal antibodies with influenza virus infection and shedding in nasopharyngeal specimens previously collected from exposed individuals. Aim 2. To measure host mucosal antibodies generated by different routes of vaccination and compare to previously identified correlates of infection and shedding.