After infection, the professional antigen presenting cells will engulf the invasion bacteria, process those antigens and then present the resulting peptides in association with MHC class to T cells (Secombes and Wang, 2012), indicating the expression of CD3γ, CD8α, CD83, MHC-2α, and CD28 genes have temporal differences after bacterial infection. The gene discussed is CD8A; the disease is bacterial infectious disease.