Immunization with a peptide mimicking Lipoteichoic acid protects mice against Staphylococcus aureus infection.

Lipoteichoic acid (LTA), a major component of the cell wall of Staphylococcus aureus (S. aureus), is not generally considered as an ideal vaccine candidate since it is a thymus-independent antigen. In this study, we screened a 12-mer phage peptide library and identified a series of peptide sequences that can mimic the epitope of LTA. A tetra-branched multiple antigenic peptide, named MAP2-3, comprising one of the positive peptide sequences (GHKEDRQWCQHS), was synthesized. Immunization with MAP2-3 induced LTA-specific IgG antibodies, prolonged the survival time, and decreased the bacterial burden in organs of mice infected with S. aureus. Moreover, passive immunization with polyclonal anti-MAP2-3 sera reduced bacterial load in organs of mice with bacteremia, alleviated acute lung injury in mice with pneumonia, and decreased the size of lesions in mice with skin infection. The number of LTA-specific antibody-secreting cells in the spleen of MAP2-3 immunized mice were significantly higher than that in the control mice. In summary, as a surrogate of LTA, vaccination with MAP2-3 elicited humoral immune response and protected mice from S. aureus infection. This study provides a new option to design vaccines against S. aureus.