Diagnosis, Treatment and prevention of infectious diseases Flashcards
Vaccines generations
- Attenuated whole agent vaccines and inactivated whole agent vaccines
- Subunit vaccines and toxoids
- Recombinant vector vaccines
- Peptide synthetic vaccines, nucleic acid vaccines, vaccines containing products of Major
Histocompartibility complex, plants vaccines
Alive vaccine/ Attenuated whole agent vaccines
Attenuated whole agent vaccines are suspensions of the microorganisms’ vaccine strains
cultivated in different nutrient substrates.
To initiate an infection without causing an injury or disease because they prepare for
microorganism’s limited in the ability to cause disease.
The immunity following alive vaccine administration resembles the type of after infections
disease. Alive vaccine induce both humoral and cellular immunity.
This immunity is life long and boosted doses may be necessary.
Examples of alive bacteria vaccines:
vaccine against tuberculosis (BCG- bacillus C and G)
vaccine against plague, tularemia, buscellosis, anthrax
Examples of viral alive vaccines:
vaccine against Rubella, molds, measles, polymyelitis and influenza.
Advantages of alive vaccines over inactivated whole agent and subunit vaccines
- Attenuated whole agent vaccines create stable and prolonged immunity similar to
postinfectious immunity. - Vaccination usually is done by a single administration of the vaccine
- Methods of administration are so simple (vaccine maybe administrated just by skin
application – scarification
Inactivated whole agent vaccines
are prepared from inactive virulent strains of bacteria and
viruses posessing complete collection of antigens. Rather than alive vaccines are used to confer
protection against bacteria and viruses.
Can be prepared by two ways:
Chemical ways – inactivation of pathogens by treating of virulent strains of pathogens by
formalin or phenol.
Physical ways – inactivation of virulent strains of microorganism by UV light and
temperature.
Examples of bacterial killed vaccines:
vaccines against cholera, leptospirosis, whooping cough,
gonorrhea, Brucellosis.
Examples of viral killed vaccines:
against rabies, tick-born- spring-summer encephalitis,
Japanese encephalitis, Hepatitis A, influenza.
Subunit vaccines
compose of only those antigenic fragments of a microorganisms that best
stimulate an immune response. They can be developed after identification of bacterial or viral
components that elicit a protective immune response. Immunogenic components are isolated
from bacteria, viruses or virus-infected cell by chemical means or vaccines are prepared through
genetic engineering involving the expression of clone viral genes in bacteria or eukaryotic cells.
Subunit vaccines that are produced by genetic engineering techniques, meaning that other
microbes are programmed to produce the desired antigenic fraction are called recombinant
vaccines.
Subunit vaccines also make or have artificial.
Vaccines with artificial adjuvant are created on the base of natural antigens and synthetic
adjuvants composition.
Creation of recombinant vaccines
First pathway
* Cloning of genes providing synthesis of necessary antigens
* Introduction of these antigens into vector.
* Introduction of vectors into recipients cells.
* Culture of recombinant cells in vitro
* Isolation of antigen and its purification
Second Pathway
* Usage recombinant cells like vaccines strains of microorganisms
Toxoid
This is vaccine of second generation. Toxoids are prepared from exotoxins of different
microorganisms types. Exotoxins are inactivated by formaldehyde application (0.3-0.4%),
heating under temperature of 37-40 degrees during 28-39 days.
Formalin and heating action causes the inactivation of toxophilic group, the toxoid losses their
toxic properties but still able to induce synthesis of protective antibodies.
The antibodies produced due to toxoid administration induces the antitoxic type of immunity.
Associated Vaccines
Associated vaccines contains antigens different in nature.
Example: DPT- this vaccine is adsorb diphtheria, pertusic, tetanus vaccines contains inactivated
bacteria diphtheria and tetanus toxoid.
Associated vaccines composed of 2 types: inactivated vaccines against DPT and toxoids
Features of effective vaccines
- Vaccine must activate additional cells taking part in the processing and presentation of
antigen - Vaccine must contain epitopes for T and B cells, providing neccssary ratio cellular and
humoral immunity. - Vaccine must easily digested by phagocytes, its epitopes must have ability to interact
with antigens MHC 1 and MHC 2 - Vaccine must induce formation of regulator, effector cells and immune memory cells
Methods of increasing immunogenic activity of vaccines
- Purification of vaccine from substances able to cause specific and non specific supression
of immune response. - Aggregation of antigen by cross link interaction and another methods of complex
formation. - Absorption of vaccine antigen on substances providing depot of antigens ( Aluminium
hydroxide, Calcium phosphate). - Mixing with oil (water oil emulsion).
- Addition of microbial, plant and another adjuvants.
- Increasing of vaccine immunogenic properties by the help of artificial carrier adjuvants.
- Covering antigen by microcapsule providing adjuvant characteristics
- Activate conditions of processing and presentation of antigen by using antigens MHC 1
or MHC 2 or antibodies to these antigens
Side effect of vaccination
ability of vaccine to cause functional and morphological changes in
macroorganism without participation of immunity.
