4.45 Flashcards
Two key public health measures have a major effect on lowering the
incidence of infectious disease:
(2)
- Public sanitation
2. Vaccines
- Public sanitation
Potable water supplies, sewage disposal, improvements in housing
- Vaccines
Prevention of infectious diseases by inducing immune responses
Vaccine -
An immunizing agent derived from microorganisms
Vaccines may consist of the following:
3
- Live, attenuated microorganisms
- Killed (irreversibly inactivated) microorganisms
- Products or derivatives of microorganisms
Active immunization -
administration of a vaccine
Passive immunization -
administration of exogenously produced
or preformed antibodies
Passive immunization - postexposure treatment
Injection of purified antibody or antibody-containing serum to provide rapid, temporary
protection or treatment.
Newborns receive natural passive immunization
maternal immunoglobulin that crosses the placenta and is present in breast milk
Uses of passive immunization: (4)
- To prevent disease after a known exposure
- To ameliorate the symptoms of an ongoing disease
- To protect immunodeficient individuals
- To block the action of bacterial toxins and prevent the
diseases they cause
Human Immune Globulins
used against:
(6)
Hepatitis A Hepatitis B Rabies Respiratory Syncytial Virus Varicella zoster Tetanus
Animal Antitoxins
used against:
(2)
Botulism
Diphtheria
Passive immunization
Limitations
(4)
sometimes antiviral antibody titers not high enough
contamination with other infectious agents
need to use early after exposure- often this is not possible
some viruses have a limited extracellular phase- herpesviruses, enteroviruses
Active immunization
Use of vaccines to elicit immune responses (2)
Inactivated, subunit, and killed vaccines Live vaccines (attenuated)
Inactivated, subunit, and killed vaccines
4
No risk of infection
Use large amounts of antigen
Inactivate or kill by chemical treatment (e.g. formalin) or heat
for bacteria, viruses, or bacterial toxins
Purify or synthesize subunits or components of the infectious agent
Inactivated, subunit, and killed vaccines
(3)
— required to boost the immunogenicity of these vaccines
Adjuvants
Alum (aluminum salt)
Modern adjuvants are designed to be or to mimic PAMPs
Adjuvants influence the type of immune response
Adjuvants required to boost the immunogenicity of these vaccines
Modern adjuvants are designed to be or to mimic PAMPs
(3)
bacterial cell wall components
synthetic polymers
bacterial toxins (attenuated)
Active immunization
Some disadvantages
(5)
- Immunity is not usually long-lived (generates a Th2 response that does not elicit
effective immune memory) - Immunity may be humoral and not cell-mediated
- The vaccine does not usually elicit a local IgA response
- Booster shots are required
- Larger doses must be used
Active immunization
Inactivated, subunit, and killed vaccines
Bacterial vaccines (5)
toxoids inactivated (killed) bacteria Vibrio cholera capsule or protein subunits of bacteria Conjugate these because polysaccharides are poor immunogens
toxoids
2
Corynebacterium diphtheriae, Clostridium tetani
capsule or protein subunits of bacteria
Capsular polysaccharide vaccines:
Haemophilus influenzae B
Conjugate these because polysaccharides are poor immunogens
Hib polysasccharide + diphtheria toxoid
Viral vaccines
2
inactivated viruses (polio, hepatitis A, influenza, and rabies) protein subunits of viruses (hepatitis B)
Active immunization
Live vaccines
(5)
Use avirulent or attenuated microorganisms
Immunization resembles the natural infection
Only a single dose usually required
Immunity is generally long-lived
No adjuvant required
