The flower

Perfect flowers have both an androecium and a gynoecium

Imperfect flowers have one or the other and are termed pistillate if they contain female reproductive structures or staminate if only male reproductive structures

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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.

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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

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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.

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Mechanisms of humoral and cell-mediated immune responses

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Many Viruses Are Neutralized by Antibodies

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

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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.