Development and Evaluation of a Microarray Platform for Detection of Serum Antibodies Against Streptococcus pneumoniae Capsular Polysaccharides.

Streptococcus pneumoniae is responsible for severe infections, causing millions of deaths yearly. Immunoglobulin G (IgG) antibodies against the capsular polysaccharide (CPS) offer S. pneumoniae serotype-specific protection. In this work, we examined the applicability of the microarray technology to detect CPS type-specific IgGs in serum, using a collection of 22 microarray-printed S. pneumoniae CPSs. First, printing of five CPSs onto nitrocellulose-coated glass slides was tested. Successful printing was only achieved for certain CPS types and concentrations. This behavior was tentatively related with diverse viscosities of the CPS solutions. Measurement of dynamic viscosities fully supported this assumption and helped to establish suitable CPS type- and concentration-dependent printing conditions. Next, the potential of CPS microarrays for detecting recognition by anti-CPS IgGs was examined using well-defined rabbit pneumococcal antisera. In all cases, the expected antiserum-CPS binding signals were detected, prompting a proof-of-concept analysis of human serum samples. Clearly distinct serum- and CPS-specific binding patterns and intensities were observed, evidencing selective detection of CPS type-specific IgGs. Compared to the ELISA assay commonly used to quantitate CPS type-specific IgGs in serum, the newly developed S. pneumoniae CPS microarrays offer the advantage of enabling the simultaneous analysis of multiple CPS-serum interactions using minute CPS amounts and significantly reduced serum volumes. Therefore, the approach could be particularly valuable for gauging the presence of CPS type-specific IgGs in human serum when sample volumes are limited and/or numerous serum samples are being examined.