Antibacterial Activity of a Modified Choline Binding Peptide Against Streptococcus pneumoniae with Corresponding Antibody

Streptococcus pneumoniae is an important human pathogen that colonizes the upper respiratory tract. The infection of influenza A virus (IAV) is associated with an increase in susceptibility to pneumococcal pneumonia. In the present study, we analyzed the antibacterial activity of ChBp-I2 with N-terminal choline binding peptide and C-terminal IAV epitope to S. pneumoniae. Three ChBp-Is with different IAV epitope were applied in pneumococcal binding test. Among which ChBp-I2 of 50 mu g/ml mediate a similar binding capacity of IAV antibody to capsular polysaccharide antibody. In the following tests, no inhibitory effect of ChBp-I2 was detected to pneumococcal cells alone. However, high concentrations of ChBp-I2 influence the synthesis of pneumococcal cell wall. Meanwhile, the growth rate, adhesion and the autolysis of pneumococcal cells are both decreased with the existence of ChBp-I2 and IAV antibodies. In vivo, the treatment of ChBp-I2 decrease the number of pneumococcal cells in lung and blood in IAV immunized mice. In conclusion, the distinctive activities of ChBp-I2 to S. pneumoniae indicate it could be a candidate for preventing secondary S. pneumoniae infection post IAV infection.