Immunisation Flashcards
What are the two types of immunisation?
Active and passive
What does immunisation involve?
using vaccines or antibody-containing preparations to provide immune
protection to provide immune protection against specific diseases
Describe passive immunisation
immediately active, effective for post-exposure prophylaxis, no memory, no need for
fully-functional immune system (eg. use in immunocompromised hosts, young, elderly)
Describe active immunisation
Vaccines - long-duration, lag before it is active, usually requires multiple immunisations
Describe passive immunisation
Passive immunisation is via immunoglobulins – provides immediate protection
Standard immunoglobulins (human, animals) – non-specific, pooled plasma from donors,
immunoglobulins vs. many common infections
Human hyperimmune serum (high titre) – specific, from donor with high titres of antibodies to a
specific virus, against specific (single) pathogen or antigen
Examples of when passive immunisation is used
rabies
hep b
What are the types of active vaccination?
Live attenuated vaccines
Killed and subunit vaccines
Vectored vaccines
Adjuvants
Goal of active vaccination
stimulating the
vaccinee’s immune system, to mount an adaptive
immune response to a specific pathogen
Describe live attenuated vaccines
May be attenuated form of virulent organism (eg. Measles, Sabin polio vaccine) or an
immunologically-related organism (eg. vacccinia)
Good things about live attenuated
Can still replicate - can spread to vaccines family
Bad things about live attenuated
Reversion to full virulence
Describe killed or ‘inactivated’ vaccines
May be whole organism, subunit, isolated toxins – antigen preparation chemically treated to
inactivate infectivity and toxicity
Describe whole organisms killed vaccines
Examples of whole organism killed vaccines
Heat or formaldehyde inactivated
shorter term immunity than attenuated vaccines (need boosters)
e.g. Cholera , Perussis
Describe subunit vaccines
Examples of subunit vaccines
- antigenic viral surface components are isolated
- these elicit a neutralising antibody response
Examples:
Influenza
Genetically engineered protein subunit from HBV
HPV
Example of inactivated exotoxin
Tetanus toxoid - need boost every 10 years
Describe conjugate vaccines
Antigenic polysaccharide from bacterial cell wall covalently-coupled (conjugated) to protein carrier
(eg. tetanus toxin); gives higher antibody titres than unconjugated polysaccharide vaccine
- Upon vaccination, the protein carrier provides peptides for MHC presentation, thus providing T cell
help for polysaccharide-specific B cells to make antibodies
Describe toxoid vaccines
Inactivated derivatives of bacterial endotoxins (eg. diphtheria toxin, tetanus toxin – Clostridium
tetani)
- Rendered non-toxic by chemical (formalin) treatment or genetic engineering, but remain immunogenic
Describe recombinant vaccines
Created via genetic engineering; the gene encoding a viral protein is inserted into a different, non-
pathogenic virus
- When the carrier virus replicates, the vaccine protein is produced, eliciting an immune response
- Examples are the hepatitis B vaccine, and human papillomavirus vaccine (HPV: a recombinant virus-
like particle is created in yeast, expressing single proteins of four different HPV strains, thus inducing
immunity to all four strains at once)
MMR vaccine issues
Adverse reactions, rarely serious – 10% of children develop fever, malaise, and a rash 5-21 days
after the first vaccination
3% develop joint pain lasting on average 18 days
Anaphylaxis is a rare but serious side effect
Controversy: Andrew Wakefield, 1998 – MMR vaccine linked to autism and enterocolitis;
discredited, but led to decline in vaccination rates and increase in disease rates
What are adjuvants?
Addition of substances that create a state of inflammation, helps stimulate effective immune
response
