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Vaccines and the Immune Response: How Vaccines Work

vaccines and the immune response how

vaccines work influenza vaccines are

able to trigger an immune response by

mimicking viral infection they are

usually manufactured using inactivated

or killed virus particles taken from

various circulating influenza strains in

active fractioned viral components

contain the sub Varian particles

hemagglutinin h a and neuraminidase na

in canada influenza vaccines are

administered via intramuscular injection

these fractioned particles containing

the foreign antigens hemagglutinin and

neuraminidase are released from the

vaccine into the bloodstream there they

are met with an immune response mediated

by various immune cells including

macrophages T lymphocytes or T cells and

B lymphocytes or b-cells

a major mechanism of action involves

macrophage phagocytosis of hemagglutinin

breaking it into smaller components

after ingestion macrophages display the

hemagglutinin antigen on their surface

in combination with a specific receptor

known as the major histocompatibility

complex or MHC t-cells are now able to

recognize and bind foreign antigens that

are associated with the MHC

upon binding to the MHC receptor T cells

become activated and proliferate into

either cytotoxic T cells regulatory

suppressor T cells or helper T cells

activated helper T cells Express

hemagglutinin receptors specific to the

vaccine strand on their surface and play

a major role in antibody generation and

memory B cell activation

unlike T cells B cells are able to

ingest hemagglutinin independent of the

MHC once internalized B cells processed

the hemagglutinin antigen and presented

on their surface in combination with an

MHC

when activated helper t-cells interact

with activated b-cells expressing

antigen MHC receptors they begin

secreting lymphokines which have several

effects

lymphokines trigger activated b-cell

proliferation which leads to either

their differentiation into memory

b-cells or into plasma cells plasma

cells produce hemagglutinin antibodies

specific to the strain of influenza

contained in the vaccine memory b-cells

aid in future immune response when

exposed to an active influenza virus

when an infected host sneezes towards an

uninfected person the nasopharynx is

exposed to aerosol droplets containing

whole live influenza virus

once inhaled the influenza virus

attempts viral colonization of

nasopharyngeal epithelial cells assuming

that the vaccine strain matches that of

the live virus hemagglutinin antibodies

block viral attachment of live influenza

virus to host epithelial cells and

overall disease is either avoided or

diminished in severity

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