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. 2017 Jun 14;12(6):e0178993. doi: 10.1371/journal.pone.0178993

Fig 15. Overview of virus-host interactions induced by attenuated and virulent strains at early stages of the immune response [50].

Fig 15

Different trends in Tc or Th cell immune responses were induced by attenuated (A) and virulent (V) strains, and the red or green colors represent the major or minor trends of immune responses. The shade represents the level of each immune trend. Virus-associated ssRNA or dsRNA was recognized by TLR7 or alternatively activated TLR3, RIG-1 and MDA5, which are vital for the production of inflammatory cytokines and type I interferons through the NF-κB, IRF3/7 or MAPK signaling pathways. Meanwhile, the viral capsid and nonstructural proteins were translated in the host cell and presented by MHC-I or MHC-II on the surface of APCs. Then, CD8+ Tc or CD4+ Th cells were activated by antigen-MHC-I or antigen-MHC-II molecules, which were stimulated by IL-2, IL-4 and IFN-γ.