Pelton, StephenShaik-Dasthagirisheb, Yazdani BashaKochis, Edward2025-10-012025-10-012024https://hdl.handle.net/2144/513872024Streptococcus pneumoniae (SP) serotypes 15B and 15C are frequent causes of invasive pneumococcal disease (IPD). The principal difference between serotypes 15B and 15C is the presence of an O-acetyl group on the pentasaccharide repeating unit of 15B polysaccharide. It remains unclear if antibodies (Ab) against SP-15B cross react with SP-15C. We evaluated anti-15B Ab activation of classical complement pathway against SP 15B and 15C and found that anti-capsular 15B antibodies induce limited C4 deposition and reduced C3 intensity on SP-15C, reflecting lower classical pathway activation in contrast to high C4 and C3 deposition on SP 15B. These observations support limited cross reactivity of anti-15B sera with 15C strains of SP.en-USMicrobiology15B15CPneumoniaeThesis/Dissertation2025-09-30