This will be technically challenging as it is highly likely there is functional redundancy for IgG binding to S. pneumoniae surface proteins, and using mutants lacking specific protein antigens to identify functionally important targets for IgG in mouse infection models will be confounded by the importance for virulence of many of the potential protein antigens (e.g. PspA, PspC, Ply, PhtD). This evidence concerns the gene SFTPC and infection.