Staphylococcus aureus Protection-Related Type 3 Cell-Mediated Immune Response Elicited by Recombinant Proteins and GM-CSF DNA Vaccine

Staphylococcus aureus mastitis remains a major challenge for dairy farming. Here, 24 mice were immunized and divided into four groups: G1: control; G2: Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF) DNA vaccine; G3: F0F1 ATP synthase subunit α (SAS), succinyl-diaminopimelate (SDD), and cysteinyl-tRNA synthetase (CTS) recombinant proteins; and G4: SAS+SDD+CTS plus GM-CSF DNA vaccine. The lymphocyte subpopulations, and the intracellular interleukin-17A (IL-17A) and interferon-γ production in the draining lymph node cells were immunophenotyped by flow cytometry. The immunophenotyping and lymphocyte proliferation was determined in spleen cells cultured with and without S. aureus stimulus. Immunization with S. aureus recombinant proteins generated memory cells in draining lymph nodes. Immunization with the three recombinant proteins plus GM-CSF DNA led to an increase in the percentage of IL-17A(+) cells among overall CD44(+) (memory), T CD4(+), CD4(+) T CD44(+) CD27(−), γδ TCR, γδ TCR(+) CD44(+) CD27(+), and TCRVγ4(+) cells. Vaccination with S. aureus recombinant proteins associated with GM-CSF DNA vaccine downregulated T(H)2 immunity. Immunization with the three recombinant proteins plus the GM-CSF DNA led to a proliferation of overall memory T, CD4(+), and CD4(+) TEM cells upon S. aureus stimulus. This approach fostered type 3 immunity, suggesting the development of a protective immune response against S. aureus.