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Fig. 1 | BMC Systems Biology

Fig. 1

From: How to prevent viremia rebound? Evidence from a PRRSv data-supported model of immune response

Fig. 1

Functional diagram of the model representing the within-host immune response to PRRSv infection. Functional diagram of the model representing the within-host immune response to PRRSv infection. Binding of PRRS viral particles (V) and naive target cells (Tn) either result in mature and non-infected cells (Tm) that phagocytes viral particles, or in mature and infected cells (Ti) that allows viral replication and excretion of new viral particles. Phagocytosis is amplified by antiviral cytokines (TNFα, IFNα, IFNγ) and inhibited by immuno-modulatory (IL10, TGFβ) cytokines; on the contrary, infection and viral replication are inhibited by antiviral cytokines and amplified by immuno-modulatory cytokines. TNFα induces the apoptosis of Tn, Tm and Ti. Viral particles are neutralised by antibodies (nAb); infected cells are cytolysed by natural killers (NK) and Cytotoxic T Lymphocytes (CTL). Mature target cells (Tm and Ti) synthesise cytokines and present the viral antigen to naive adaptive effectors (En, not explicitly represented in the model). Once activated, they differentiate into cellular (Ec), humoral (Eh) or regulatory (Er) effectors, depending on the cytokinic environment. Pro-cellular regulatory cytokines (IFNγ, IL12) favour Ec, whereas pro-humoral regulatory cytokines (IL4, IL6) Eh and pro-regulatory regulatory cytokines (TGFβ) Er. These effectors synthesise cytokines and induce the activation of plasma cells (B), which synthesise nAb. Moreover, Ec induce the activation of CTL. Finally, the recruitment of Tn and NK is amplified by pro-inflammatory cytokines (Pi, which groups IL1β, IL6, IL8 and CCL2). Colours – green: PRRSv particles; red: innate response; blue: adaptive response; purple: both innate and adaptive responses. Lines – plain with arrow: state changes; dashed (dotted) with arrow: (cytokine) syntheses; plain dark grey with : up-regulations by cytokines; plain light grey with : down-regulations by cytokines

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