2.2 Vaccine Antigens: Definitions and Concepts

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Questions and Answers

Name the Types of vaccines and an example of each ( tip 9)

Live attenuated= Measles, Killes whole organism=whole cell pertussis, toxoid=tetanus, subunit recombinant protein = pertussis, Virus like particle= Human papillomavirus, OMV= Group B meningoccal, Protein-polysacharide conjugate= typhoid, Vrial vector= ebola, Nucleic acid= Covid

What is the difference between an antigen and an immunogen?

Antigen is a structure with 'in vitro' immunologic reactivity, while an immunogen is a structure that induces 'in vivo' immune response.

What is needed for a subsequent efficient induction of an innate and adaptive immune response?

Antigen + 'defensive triggers'

What are the two types of pathogen-based antigens mentioned in the text?

Non-replicating (whole inactivated pathogen) and replicating (live-attenuated pathogen) Signup and view all the answers

What type of vaccines use inactivated toxins as antigens?

Toxoids Signup and view all the answers

What are the different types of pathogen subunit antigens mentioned in the text?

Split virus, fragments of pathogens, purified antigens (protein antigens, recombinant proteins), Signup and view all the answers

What are the key advantages of the novel vaccine technologies such as viral vectors and mRNA?

Production speed and cost Signup and view all the answers

What determines the final choice of antigen in vaccine development?

Technological achievability and safety/immunological perspective Signup and view all the answers

Give an example of a live-attenuated vaccine.

MMR(-V) vaccine, OPV, rotavirus vaccine Signup and view all the answers

What is the process involved in creating a live-attenuated vaccine?

Wild virus replication in unfavourable conditions in cell culture, repeated to produce an attenuated strain Signup and view all the answers

What is the mechanism used to create reassortant live-attenuated vaccines?

Reassortment via co-infection with wild and attenuated virus strains Signup and view all the answers

How are killed/inactivated vaccines produced?

Virus growth under suitable conditions, purification, and treatment with heat or chemicals Signup and view all the answers

What are the advantages of live-attenuated vaccines over killed/inactivated vaccines?

Mimic natural infection, retain most defensive triggers/immunogenic elements, strong priming, long-term persistence of immunity Signup and view all the answers

What is the main disadvantage of live-attenuated vaccines?

Rare reversion to virulence; unsuitable for immunocompromised subjects Signup and view all the answers

What factor affects the stability of live-attenuated vaccines over time?

Heat labile Signup and view all the answers

What is a potential drawback of live-attenuated vaccines when administered with blood or blood-derived products or in presence of maternal antibodies in infants?

Immunological interference with other live vaccines Signup and view all the answers

Study Notes

Types of Vaccines

There are several types of vaccines, including:
- Inactivated/killed vaccines
- Live-attenuated vaccines
- Subunit vaccines
- Conjugate vaccines
- Viral vector vaccines
- mRNA vaccines

Differences between Antigen and Immunogen

An antigen is a substance that can trigger an immune response, but may not necessarily induce immunity
An immunogen is a substance that can trigger an immune response and induce immunity

Requirements for Immune Response

For a subsequent efficient induction of an innate and adaptive immune response, the presence of pattern recognition receptors, antigen presentation, and costimulation are needed

Pathogen-based Antigens

Two types of pathogen-based antigens mentioned are:
- Inactivated toxins
- Pathogen subunit antigens

Subunit Antigens

Pathogen subunit antigens can be further divided into:
- Protein-based antigens
- Polysaccharide-based antigens
- Conjugate antigens

Viral Vector and mRNA Vaccines

The key advantages of viral vector and mRNA vaccines include:
- Rapid development and production
- Flexibility in design
- Ability to induce both innate and adaptive immune responses

Antigen Selection

The final choice of antigen in vaccine development is determined by:
- The type of pathogen
- The immune response required
- The potential for immune evasion

Live-attenuated Vaccines

Example of a live-attenuated vaccine: MMR vaccine
To create a live-attenuated vaccine, the pathogen is weakened through serial passage, genetic modification, or chemical treatment
The mechanism used to create reassortant live-attenuated vaccines is:
- Genetic reassortment of different viral strains

Killed/Inactivated Vaccines

Killed/inactivated vaccines are produced by:
- Killing the pathogen through heat, chemicals, or radiation
- Inactivating the pathogen's ability to replicate

Advantages of Live-attenuated Vaccines

Advantages of live-attenuated vaccines over killed/inactivated vaccines include:
- Induction of both innate and adaptive immune responses
- Longer-lasting immunity
- Mucosal immunity

Disadvantages of Live-attenuated Vaccines

The main disadvantage of live-attenuated vaccines is:
- The risk of reversion to virulence
The stability of live-attenuated vaccines over time can be affected by:
- Temperature fluctuations
- Storage conditions
A potential drawback of live-attenuated vaccines is:
- Interference with the vaccine's ability to induce immunity when administered with blood or blood-derived products or in the presence of maternal antibodies in infants

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Description

Test your knowledge on vaccine antigens by understanding the definitions of antigens and immunogens, and their role in inducing immune responses. Explore the concepts of antigen-antibody interactions and their significance in vaccine development.