Vaccines Flashcards
What is passive immunization?
Immunity that can be transferred to a naive individual by transferring antibodies or cells from another individual already immune to an infection
E.g. maternal IgG and IgA in breast milk
What are the uses for passive immunization?
Prevent disease after known exposure
Ameliorate symptoms of an ongoing disease
Protect immunodeficient individuals
Block action of bacterial toxins
What is Immune serum globulin?
Human serum globulin prepared from pooled plasma and contains the normal repertoire of antibodies for an adult
IVIG, SCIG, IMIG
What can immune serum globulin be used for?
Protection
Alloimmunization
Suppression of autoimmune and inflammatory processes
What is hyperimmune globulin?
Made by selecting human plasma with high titers of the desired antibody or by specifically immunizing donors to produce such antibodies
What is active immunization?
Occurs when an immune response is stimulated due to a challenge from an immunogen
Infection and vaccines
What is a major difference between the vaccine response to protein antigens and polysaccharide antigens?
Protein antigens - activated B cells are further activated by Tfh cells, causing isotype switching from IgM to IgG, A or E
Polysaccharide - No Tfh signal, plasma cells secrete low levels of low specificity IgM, IgG, or IgA
How are B memory cells generated?
During the T-dependent response, along side plasma cells, memory B cells differentiate
These cells migrate toward the extrafollicular areas of spleen and nodes
Upon second exposure to their specific antigen, the secrete large amounts of high-affinity antibodies
What type of antigen induces a secondary response?
Only protein antigens can induce a secondary response because the primary response is T-dependent
What are inactivated vaccines?
Composed of Killed or inactivated whole viruses or bacteria
Can be killed or inactivated whole viral or bacterial vaccines, subunit vaccines, toxoid vaccines, or conjugate vaccines
How do inactivated vaccines work?
Use a large amount of antigen to elicit a protective antibody response but without risk of infection with the agent
Generally safe except in people who are allergic to components
What are inactivated vaccines usually administered with?
An adjuvant
Boosts their immunogenicity by enhancing uptake by or stimulating dendritic cells and macrophages
E.g. stimulate TLRs to activate APCs
What is the adjuvant in most vaccines?
Most are precipitated onto aluminum
MF59 (squalene in oil and water) and monophosphoryl lipid A (MPL) are sometimes used in newer vaccines
How are killed/inactive whole bacterial or viral vaccines made?
Created from microorganisms that have been killed through physical or chemical processes
What may be required to induce a sufficient immune response from inactivate whole-cell vaccines?
Multiple doses
What are subunit vaccines?
Consists of bacterial or viral components that elicit a protective immune response
What is a toxoid vaccine?
Made from a toxin from bacteria that has been inactivated by treatment with formalin but that elicits an immune response
What are conjugate vaccines?
Used when the antigen is a polysaccharide such as the capsular components of some bacteria
What are the disadvantages to inactivated vaccines?
Immunity may only be humoral and not lifelong
Typically does not elicit local IgA response
Booster shots and larger doses required
What are live vaccines?
Prepared with organisms limited in their ability to cause disease, i.e. avirulent or attenuated
Useful for protection against infections caused by enveloped viruses that require T-cell immune responses for resolution of the infection
How are live viral vaccines attenuated?
Grown n embryonated eggs or tissue culture at nonphysiologic temperatures and away from selective pressures of the host immune response
What are the disadvantages to live vaccines?
Vaccine virus may still be dangerous for immunosuppressed people
Vaccine may revert to a virulent viral form
Viability of the vaccine must be maintained
What are DNA plasmid vaccines?
A plasmid that carries genes encoding proteins from the pathogen of interest
Protein product is expressed
