Chapter 15: Vaccines and Diagnostic Testing

Variolation

The historical practice of infecting a healthy individual with material from a smallpox scab to induce immunity

• Discontinued due to the risk of death

Types of Immunity

1.) Active Immunity

2.) Passive Immunity

Natural Active Immunity

This type of immunity is acquired from exposure to infectious disease

Artificial Active Immunity

This type of immunity is induced by vaccination

Natural Passive Immunity

This type of immunity is the transfer of immunity via mother-child relationship

Artificial Passive Immunity

This type of immunity occurs when a person receives immunity substances from another human or animal

Natural Passive Immunity

This type of immunity is passed from mother to child which enables

• Antibodies to be passed to fetus during pregnancy

• Antibodies to be passed in breastmilk

This is temporary, lasting only weeks to months after birth

Artificial Passive Immunity

This type of immunity focuses on artificial passive immunotherapy

Artificial Passive Immunotherapy

The process of this involves

• Administration of antiserum containing preformed antibodies

• Provides immediate protection

• Made in other organisms

  • Anti-toxin to botulism, diphtheria (bacteria toxin)

  • Anti-venoms to bites & stings (snake & jellyfish)

• Antisera have several limitations

  • Serum sickness:  allergic reactions against foreign antigens

  • Antibodies of antisera are degraded relatively quickly

Types of Artificial Passive Immunotherapy

1.) Intravenous Immune (Gamma) Globulin (IVIG)

2.) Specific Immune Globulin (SIG)

3.) Monoclonal Antibodies

Intravenous Immune (Gamma) Globulin (IVIG)

This type of artificial passive immunotherapy is extracted from a large pool of human donors, containing a broad spectrum of antibodies

• Used to treat inflammatory diseases and support immunocompromised

Specific Immune Globulin (SIG)

This type of artificial passive immunotherapy is extracted from patients who are recovering or have developed immunity from a specific infection, containing higher amounts of specific antibodies

• Used to treat pertussis, tetanus, rabies

Monoclonal Antibodies

This type of artificial passive immunotherapy is produced in a lab that is highly specific, recognizing and binding to one antigen only with the purpose of precisely binding to the target to neutralize/mark for destruction

• Administered intravenously, short-lived

• Used to treat cancers, autoimmune                       disorders & infectious disease

Characteristics of Effective Vaccines (Artificial Active Immunity)

• Protects against natural, wild form of pathogen

• Few or no adverse side effects or toxicity

• Stimulates both cell and antibody mediated immune responses

• Long term, lasting effects

• Should not require boosters

• Inexpensive, long shelf life and easy to administer

Artificial Active Immunity Vaccine Types

1.) Whole Cell

2.) Subunits

Whole Cell Vaccine

This type of artificial active immunity vaccine uses the entire microbe

• Attenuated (live)

• Inactivated

• Virus Like Particles (LVP)

Attenuated (Live) Vaccine

This type of vaccine uses the whole microbe (whole cell) whose virulence has been lessened

• Advantage —> stimulates a strong immune response, long lasting, fewer boosters

• Disadvantage —>  special storage, shouldn’t be administered to pregnant woman or immunosuppressed, concern of reverting to wild type

Inactivated (Killed) Vaccine

This type of vaccine uses the whole microbe (whole cell) and kills is through heat, radiation, chemicals

• Advantage —> safer than live vaccines, easier to store

• Disadvantage —> weaker immune response, need larger doses and more boosters, often contain adjuvants

  • Chemicals added to increase effective antigenicity

Virus Like Particles (VLP) Vaccines

This type of vaccine uses the whole virus (whole cell), but no genetic material which means it cannot replicate or cause infection, but closely resembles the actual pathogen, triggering a strong immune response

• Ex: HPV vaccines, HBV vaccines

Toxoid Vaccines

This type of vaccine only uses a portion (subunit) of the microbe, but is useful for infections in which exotoxins cause disease and not the microbe itself

• Chemically or thermally modified toxins used to stimulate immunity

• Require multiple doses and an adjuvant, few antigenic sites

Adjuvant

A substance added to vaccines to enhance, accelerate, or prolong the body’s specific immune response to an antigen without being antigenic itself

Gene Technology Vaccines

This type of vaccine only uses a portion (subunit) of the microbe, but antigenic subunits are synthesized to mimic molecules found on pathogen

• Subunits synthesized in bacteria or yeast in laboratory

• Subunits are produced by host cells upon exposure to nucleic acids containing instructions for pathogenic subunit

Disadvantages of Vaccines

• Mild toxicity most common

  • Pain at injection site, general flu-like symptoms

• Risk of anaphylactic shock is rare

• Allegations of vaccines causing autism and other conditions have not been substantiated

Herd Immunity

The process in which high immunization rate in a community provides indirect protection to the vulnerable

• Percentage of population needed to provide herd immunity dependent on rate of contagiousness