Immunoprophylaxis(prophylactic immunization)

Immunoprophylaxis

• Types of immunization

• Immunoglobulins and vaccines

• Strategies in vaccine preparation

• Mechanisms of action of different types of vaccines

NATURAL

ARTIFICIAL (PROPHYLACTIC)

ACTI

VE

PASS

IVE

IMMUNIZATION

Immunity after infectionTransplacental transfer of IgG

Immunoglobulines in milk (breast feeding)

Immunoglobulins and antisera (antitoxins)

Vaccination

Pasive immunization(Administration of immunoglobulins/antisera)

For prophylaxis or therapy

Human immunoglobulins (from blood donors)

Animal (horse) sera (antisera, antitoxins)

e.g. for snake venoms, botulism, diphteria...

immediate effect

temporary immunity (weeks, months)

Antibodies-Immunoglobulins (Ig)

- human serum (gama)globulin (Ig of various specificity)

- specific immune globulins (high-titre of specific Ig)

serum disease!!!

e.g. for hepatitis B, tetanus, rabies...

e.g. for immunodeficiencies...

Active immunization(Vaccination)

Requires time (weeks) for induction of immune response

Administration

Long-lasting immunity

- prior to exposure to pathogen (exception: rabies vaccine)

- post-exposure (in combination with specific Ig)

- multiple doses needed for most vaccines

Herd immunity

Primarily for prophylaxis

Adjuvant

- increases immunogenicity

Vaccine types

Live (attenuated) vaccines

Inactivated (killed) vaccines

- contain killed whole infectious agents

Conjugate vaccines

- contain structural parts/products of infectious agents

New approches for vaccines

obtained from pathogens by isolation and purification

synthetic (genetic engineering)

Subunit (antigenic) vaccines

- contain live, attenuated (weakend) infectious agents

Combined (polyvalent) vaccines

- contain T-independent antigen bound to T-dependent antigen

- contain several antigens of one or more different pathogens

Live (attenuated) vaccines

Examples

AdvantagesInduction of both humoral (Abs) and cellular response (CTLs)

Several viral vaccines (against polio (oral-Sabin), mumps, measles, rubella, varicella) and some bacterial (BCG for tuberculosis)...

Long-lasting immunity (administered in one or two doses)

LimitationsRisk in immunocompromised persons

Instability (termolabile)

PrincipleImunization with attenuated (weakened) pathogen

BCG (limited efficacy)

Inactivated (killed) vaccines

Greater stability

Vaccines against pertussis, typhoid, polio (Salk), influenza...

Safety (no risk of infection)

Shorter immunity (multiple, booster administration required)

Low immunogenicity (only Ab induced, adjuvant required)

Examples

Advantages

Limitations

Principle

Imunization with killed (inactivated) whole infective agents

Subunit (antigenic) vaccines

Vaccine against pertussis (acellular), tetanus and diphteria (toxoid),influenza (Hemagglutinin and Neuraminidase), hepatitis B (HBsAg) andhuman papilloma virus (L1 protein) – so-called virus-like particles (VLP),pneumococcal and meningococcal polysaccharide vaccines...

Same as for inactivated vaccines (lower immunogenecity)

Examples

Advantages

Limitations

Principle

Same as for inactivated vaccines (greater safety)

Immunization with structural antigens (protein or polysaccharide) of pathogens or their products (e.g. toxoid)

Conjugate vaccinesPrinciple

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

Good immune response to capsular antigens

Vaccines against pneumococcus, menigococcus and H. influenzae type B(capsular polysaccharide bound to diptheria toxoid )

Efficient in children in the first two years of life and asplenic persons

Relatively high cost

Same as for subunit vaccines

Example

Advantages

Limitations

PrincipleImmunization with capsular polysaccharide antigen of one pathogen (weak immunogen in children) conjugated to protein antigen of another pathogen (strong immunogen)

Same as for subunit vaccines

Combined (polyvalent) vaccines

Practical (fewer administration, fewer visits of doctor...)

Vaccines against tetanus, diphtera and pertussis (DTP), measles, mumps and rubella (MMR), polysaccharide or conjugate pneumococcal vaccines...

Same as for single vaccines

Examples

Advantages

Limitations

PrincipleSimultaneous immunization with several serotypes of one pathogen (either attenuated strains or antigens) or several different pathogens

The same as for appropriate single vaccines

Good immune response to every component in vaccine

New approaches for vaccines(Hybride vaccines with live viral vectors)

Immunization with live viral vectors (e.g. vaccinia virus) withintroduced genes for immunodominant peptides of different pathogens

Repeated administration not possible

Ongoing clinical trials for several vaccines (e.g. against HIV)

Examples

Advantages

Limitations

Principle

Induction of both humoral (Abs) and cellular immune response (CTLs)

Possibility of polyvalent vaccine preparation

Injection of bacterial plasmid with DNA containing genes for various microbial antigenes

Mechanism of action and possible adverse effects not well understood

Ongoing clinical trials for several pathogens

Simple handling, possibility of polyvalent vaccines preparation

Example

Advantages

Limitations

Principle

Induction of both humoral (Abs) and cellular immune response (CTLs)

New approaches for vaccines(DNA vaccines)

transplacental transfer of IgGj.Adjuvants increase 10.

immunogenicity of antigens in vaccinesi.Conjugate vaccines induce production of9.

immunity after recovery from infectious disease

h.Combined vaccines contain8.

high-affinity antibodies to polysaccharidesg.Inactivated vaccines contain7.

parts of infective agents or their productsf.

Subunit vaccines contain6.

induce production of mucosal IgAe.Live attenuated vaccine against polio5.

whole killed microorganisms d.Example of natural passive immunization is

4.

immunity to tetanus after injection ofantitetanus immunoglobulins

c.Example of natural active immunization is

3.

immunity to tetanus after injection of tetanus toxoid

b.Example of artificial passive immunization is

2.

antigens from different infectious agentsa.Example of artificial active immunization is

1.

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