CD4 and infection: Rozas-Serri et al. (26) showed that P. salmonis induces the inflammatory and IFN-mediated response, modulation of Th1 polarization, reduced antigen processing and presentation, modulation of the evasion of the immune response mediated by CD8+ T-cells and promotion of the CD4+ T-cell response during the late stage of infection as a mechanism to escape host defenses.