We previously found that higher nasopharyngeal (NP) antibody levels to vaccine candidate proteins PhtD, PcpA and Ply significantly correlated with reduced risk of AOM (Xu et al Clin Micro Infect 2017).
Mucosal NP IgA and IgG antibody levels to PhtD, PcpA, and PlyD were measured by ELISA from stringently-defined otitis prone (sOP) and non-otitis prone (NOP) children from Rochester NY at 7 specific time points between age 6 and 36 months old when they were healthy. Logistic regression modeling was used to determine if age-specific antibody levels could be used as a biomarker to identify the sOP child.
Mucosal PhtD IgA, PcpA IgG and IgA, and PlyD IgA antibody levels were significantly lower among sOP children across the age span studied. Age-specific PhtD IgA levels during health proved a suitable biomarker to distinguish sOP from NOP (p< 0.001), AUC=0.81, sensitivity 0.84, specificity and 0.7. PhtD IgA predicted sOP status with average accuracy of 84% without knowledge of prior NP colonization or AOM infection history.
Age-specific mucosal PhtD IgA levels may be a useful biomarker to define children who are more likely to become otitis prone.