24 - Immunization against viral diseases, types of viral vaccines

Question 1

Immunization against viral diseases

What type of immunization is used?

Answer 1

• Active immunization
  
  • ​Preventive method
  • More widespread form to control viral diseases and prevent economic losses
  • Drawback: coexistence with the virus
  • Most vaccines do not stop infections (often without clinical symptoms)

Question 2

Immunization against viral diseases

General rule of active immunization

Answer 2

• Inhibitory effect of maternal antibodies
• Negative phase
• Vaccination schedules
• Avoid immunosuppression

Question 3

Immunization against viral diseases

Name the vaccine types

Answer 3

• Monovalent
  
  • ​ A vaccine that immunize against a single antigen or single microorganism
• Polyvalent
  
  • ​ A vaccine that immunizes against more than one strain of an antigen

Question 4

Types of viral vaccines

What can viral vaccines be divided into?

Answer 4

1. ​​Live viral vaccines​
2. Inactivated (killed) vaccines
3. Subunit vaccines
4. Antiidiotype vaccines

Question 5

Types of viral vaccines

1. Live virus vaccines

Answer 5

• Live vaccines use a weakened form of the germ that causes a disease
• Because these vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response

1. Virulent (wild type) virus vaccines
   
   • Different entry site: i.e. contagious echtyma (orf)
2. Attenuated vaccines
   
   • Naturally occurring mutants (isolation)
     
     • Newcastle disease
   • Artificially attenuated viruses
     
     • Serial passages (in alien host, in embryonated eggs, in cell cultures)
     • Selection of thermo-sensitive mutants
     • Genetic modification (deletion mutants)
     • → marker, DIVA vaccines (IBR, Aujeszky’s disease)
   • Heterotypic vaccines
     
     • Marek’s disease – Turkey herpes
     • Smallpox – vaccinia virus
   • Virus-vectored vaccines
     
     • Introduction antigens into apathogen viruses

Additional information:

• Used to protect against:
  
  • Smallpox
  • Chickenpox
  • Yellow fever

Question 6

Types of viral vaccines

2. Inactivated (killed) vaccines

Answer 6

• Inactivated vaccines use the killed version of the germ that causes a disease
• Inactivated vaccines usually don’t provide immunity (protection) that’s as strong as live vaccines. So you may need several doses over time (booster shots) in order to get ongoing immunity against diseases
• The virus is not able tom multiply
• Inactivating agents:
  
  • Formalehyde
  • Ethylenimine, ethyl-ethylenimine
  • ß-propyolacton
• Adjuvants:
  
  • Added to a vaccine to boost the immune response to produce more antibodies and longer-lasting immunity, thus minimizing the dose of antigen needed
  • Slow antigen release, depo-effect
  • Immunostimulation
  • AIOH₃, saponine, oil
• Booster shot is necessary

Additional information:

• Used to protect against:
  
  • Hepatitis A
  • Flu
  • Polio
  • Rabies

Question 7

Types of viral vaccines

3. Subunit vaccines

Answer 7

• Use specific pieces of the germ, like its protein, surag or capsid
• Subunit vaccines do not contain live components of the pathogen
  
  • Subunit vaccine vs inactivated vaccines:
    
    • They differ from inactivated whole-cell vaccines, by containing only the antigenic parts of the pathogen. These parts are necessary to elicit a protective immune response.
• Contains only proteins responsible for neutralization
• Production:
  
  • Purifed virus after normal production
    
    • Chromatography
    • IScom
  • Purification of proteins by manipulating bacteria/cells
  • Synthesis of short peptides → maturation of polypeptides
• Advantages:
  
  • Safe (without nucleic acid)
  • Opportunity for differentiation (ELISA)
• Disadvatages:
  
  • Expensive
  • Only parental administration
  • In vivo the immune response are usually weaker
    
    • Often a response can be elicited, but there is no guarantee that immunological memory will be formed in the correct manner

Question 8

Types of viral vaccines

Antiidiotype vaccines

Answer 8

• Anti-idiotypic vaccines comprise antibodies that have three-dimensional immunogenic regions, designated idiotopes
• Consist of protein sequences that bind to cell receptor
• Absolutely safe vaccines
• Epitope and paratope groups (“key and lock” theory)
• Production:
  
  • An animal species “A” (e.g. cow) immunized with a viral antigen → IgG “A” is purified
  • Animals species “B” (e.g. sheep) immunized with IgG “A” → IgG “B”created
  • FAB of igG”B” → viral antigen

Additional information:

• Mainly used form high risk cancer patients
• Anti-idiotype vaccines can stimulate the body to produce antibodies against tumor cells