Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”).

TLS Online TPP Program

#Id: 9916

#Unit 4. Cell Communication and Cell Signaling

Viral Infections

Virus enters a cell via a cell-surface receptor for which it has affinity and preempts cell biosynthetic machinery to replicate all components of itself, including its genome.

This genome replication step is often error prone, generating numerous mutations.

TLS Online TPP Program

#Id: 9917

#Unit 4. Cell Communication and Cell Signaling

Influenza virus binds to sialic acid residues

Rhinovirus binds to intercellular adhesion molecules (ICAMs)

Epstein Barr virus (EBV) binds to type 2 complement receptors on B cells

TLS Online TPP Program

#Id: 9918

#Unit 4. Cell Communication and Cell Signaling

Innate response elements commonly engaged by encounter with viral PAMPs, such as secretion of type I interferons, inflammasome and NK-cell activation, as well as IL-12 production.

TLS Online TPP Program

#Id: 9919

#Unit 4. Cell Communication and Cell Signaling

Mechanisms of humoral and cell-mediated immune responses

TLS Online TPP Program

#Id: 9920

#Unit 4. Cell Communication and Cell Signaling

Many Viruses Are Neutralized by Antibodies

Antibodies are particularly effective if they are localized at the site of viral entry into the body.

TLS Online TPP Program

#Id: 9921

#Unit 4. Cell Communication and Cell Signaling

Cell-Mediated Immunity against Virus

Both CD8+ TC cells and CD4+ TH1 cells are required components of the cell-mediated antiviral defense.

Activated TH1 cells produce IL-2, IFN-ϒ, and tumor necrosis factor-α.