Question

. Describe the immune response (both humoral and cell-mediated) to Ebola and Coronavirus that typically occurs (please include a graphic depiction).

Answer 1

There are two types of immunity:-

• Innate Immunity
• Adaptive Immunity

Both types of immunity have been briefly explained below in the form of a flowchart.

The general immune response against any foreign antigen is explained below:-

The immune responses of the coronavirus and Ebola after the infection is explained below:-

• The virus infects the macrophages which later present virus antigens to T cells. This results in the activation and differentiation of the T cells. The cytokines production linked with the different T cell subsets takes place, followed by a huge release of cytokines for the amplification of the immune response.
• Due to viral persistence, the regular production of these mediators has a negative effect on NK (Natural Killer Cells), and CD8 T cell activation. Though, CD8 T cells generate very efficient mediators to clear CoV.
• The genomic RNA appears in the cytoplasm due to attachment of the virus to DPP4R on the host cell via S protein. During virus replication, a partial immune response can be generated to dsRNA.
• The production of proinflammatory cytokines and type I IFNs takes place due to the activation of the cascades of signaling pathways (NF‐κB activation and IRFs, respectively) and sensitization of TLR‐3 by dsRNA. The type I IFNs production is essential to intensify the release of antiviral proteins for the uninfected cell's protection.
• The accessory proteins of the virus can hinder the TLR‐3 signaling and bind the dsRNA of Coronavirus at the time of replication to inhibit the activation of TLR‐3 and evade the immune response. The S protein might be recognized by TLR‐4 that will eventually result in the activation of proinflammatory cytokines via the MyD88‐dependent signaling pathway.
• The strong production of immune mediators results from virus‐cell interactions. In response to virus infection, the secretion of large quantities of cytokines and chemokines is promoted in infected cells. In turn, these chemokines and cytokines recruit leukocytes and lymphocytes to the site of infection.

The adaptive and innate immune responses of Coronaviruses infection at the time of infection is shown in the image below:-

Here in this diagram, the red lines refer to inhibitory effects and green lines refer to activating effects.