“…The dominant antigens identified from the xMAP bead assay may correspond to the dominant antigens seen on the immunoblots of whole-cell lysates, as PsaA has an estimated molecular mass of 33.7 kDa, and PpmA, CbpD, Ply, and PspA have estimated molecular masses of 35, 50.3, 52.5, and 62 kDa, respectively. The antigens included in the xMAP bead assays were largely pneumococcal surface proteins, many of which are conserved between strains and known to protect against invasive S. pneumoniae infections in animal models when used as protein vaccines (1,2,4,7,21,24). However, although vaccination with ⌬pab strains induced strong protection against subsequent infection with the homologous wild-type S. pneumoniae strain, vaccination with the ⌬pab strain failed, surprisingly, to induce biologically significantly protection against infection with heterologous strains, even after a two-dose vaccination schedule.…”