Immunoprophylaxis
(prophylactic immunization)
Immunoprophylaxis
• Types of immunization
• Immunoglobulins and vaccines
• Strategies in vaccine preparation
• Mechanisms of action of different types of vaccines
NATURAL
Transplacental transfer of IgG
Immunity after infection
PASSIVE
ACTIVE
Immunoglobulines in milk
(breast feeding)
IMMUNIZATION
Immunoglobulins and
antisera (antitoxins)
Vaccination
ARTIFICIAL
(PROPHYLACTIC)
Pasive immunization
(Administration of immunoglobulins/antisera)
For prophylaxis or therapy
immediate effect
temporary immunity (weeks, months)
Antibodies-Immunoglobulins (Ig)
Human immunoglobulins (from blood donors)
- human serum (gama)globulin (Ig of various specificity)
e.g. for immunodeficiencies...
- specific immune globulins (high-titre of specific Ig)
e.g. for hepatitis B, tetanus, rabies...
Animal (horse) sera (antisera, antitoxins)
e.g. for snake venoms, botulism, diphteria...
serum disease!!!
Active immunization
(Vaccination)
Primarily for prophylaxis
Requires time (weeks) for induction of immune response
Administration
- prior to exposure to pathogen (exception: rabies vaccine)
- post-exposure (in combination with specific Ig)
Adjuvant
- increases immunogenicity
Long-lasting immunity
- multiple doses needed for most vaccines
Herd immunity
Vaccine types
Live (attenuated) vaccines
- contain live, attenuated (weakend) infectious agents
Inactivated (killed) vaccines
- contain killed whole infectious agents
Subunit (antigenic) vaccines
- contain structural parts/products of infectious agents
obtained from pathogens by isolation and purification
synthetic (genetic engineering)
Conjugate vaccines
- contain T-independent antigen bound to T-dependent antigen
Combined (polyvalent) vaccines
- contain several antigens of one or more different pathogens
New approches for vaccines
Live (attenuated) vaccines
Principle
Imunization with attenuated (weakened) pathogen
Examples
Several viral vaccines (against polio (oral-Sabin), mumps, measles, rubella,
varicella) and some bacterial (BCG for tuberculosis)...
Advantages
Induction of both humoral (Abs) and cellular response (CTLs)
Long-lasting immunity (administered in one or two doses)
Limitations
Risk in immunocompromised persons
Instability (termolabile)
BCG (limited efficacy)
Inactivated (killed) vaccines
Principle
Imunization with killed (inactivated) whole infective agents
Examples
Vaccines against pertussis, typhoid, polio (Salk), influenza...
Advantages
Greater stability
Safety (no risk of infection)
Limitations
Low immunogenicity (only Ab induced, adjuvant required)
Shorter immunity (multiple, booster administration required)
Subunit (antigenic) vaccines
Principle
Immunization with structural antigens (protein or polysaccharide) of
pathogens or their products (e.g. toxoid)
Examples
Vaccine against pertussis (acellular), tetanus and diphteria (toxoid),
influenza (Hemagglutinin and Neuraminidase), hepatitis B (HBsAg) and
human papilloma virus (L1 protein) – so-called virus-like particles (VLP),
pneumococcal and meningococcal polysaccharide vaccines...
Advantages
Same as for inactivated vaccines (greater safety)
Limitations
Same as for inactivated vaccines (lower immunogenecity)
Conjugate vaccines
Principle
Immunization with capsular polysaccharide antigen of one pathogen
(weak immunogen in children) conjugated to protein antigen of another
pathogen (strong immunogen)
Principle of immunization with conjugated vaccines
Principle of immunization with conjugated vaccines
Principle of immunization with conjugated vaccines
Principle of immunization with conjugated vaccines
Conjugate vaccines
Principle
Immunization with capsular polysaccharide antigen of one pathogen
(weak immunogen in children) conjugated to protein antigen of another
pathogen (strong immunogen)
Example
Vaccines against pneumococcus, menigococcus and H. influenzae type B
(capsular polysaccharide bound to diptheria toxoid )
Advantages
Same as for subunit vaccines
Good immune response to capsular antigens
Efficient in children in the first two years of life and asplenic persons
Limitations
Same as for subunit vaccines
Relatively high cost
Combined (polyvalent) vaccines
Principle
Simultaneous immunization with several serotypes of one pathogen
(either attenuated strains or antigens) or several different pathogens
Examples
Vaccines against tetanus, diphtera and pertussis (DTP), measles,
mumps and rubella (MMR), polysaccharide or conjugate pneumococcal
vaccines...
Advantages
The same as for appropriate single vaccines
Good immune response to every component in vaccine
Practical (fewer administration, fewer visits of doctor...)
Limitations
Same as for single vaccines
New approaches for vaccines
(Hybride vaccines with live viral vectors)
Principle
Immunization with live viral vectors (e.g. vaccinia virus) with
introduced genes for immunodominant peptides of different pathogens
Examples
Ongoing clinical trials for several vaccines (e.g. against HIV)
Advantages
Induction of both humoral (Abs) and cellular immune response (CTLs)
Possibility of polyvalent vaccine preparation
Limitations
Repeated administration not possible
New approaches for vaccines
(DNA vaccines)
Principle
Injection of bacterial plasmid with DNA containing genes for various
microbial antigenes
Example
Ongoing clinical trials for several pathogens
Advantages
Induction of both humoral (Abs) and cellular immune response (CTLs)
Simple handling, possibility of polyvalent vaccines preparation
Limitations
Mechanism of action and possible adverse effects not well understood
1. Example of artificial active
immunization is
a. antigens from different infectious agents
2. Example of artificial passive
immunization is
b. immunity to tetanus after injection of
tetanus toxoid
3. Example of natural active
immunization is
c. immunity to tetanus after injection of
antitetanus immunoglobulins
4. Example of natural passive
immunization is
d. whole killed microorganisms
5. Live attenuated vaccine against polio
e. induce production of mucosal IgA
f. parts of infective agents or their products
6. Subunit vaccines contain
g. high-affinity antibodies to polysaccharides
7. Inactivated vaccines contain
8. Combined vaccines contain
h. immunity after recovery from infectious
disease
9. Conjugate vaccines induce production of
10. Adjuvants increase
b
1.____
c
2.____
h
3.____
i. immunogenicity of antigens in vaccines
j. transplacental transfer of IgG
j
4.____
e
5.____
f
6.____
d
7.____
a
8.____
g
9.____
h
10.___