WEEK 10: VACCINATIONS Flashcards
The first major barrier to infectious agents is…..
Skin
Apart from skin, the next main barrier to infectious agents is ….
- Chemical barriers e.g. lysozyme in tears (targets peptidogylcans)
The final way to control infectious agents is _____ which is composed of three main types of cell:
- _____
- ____
- _____
- Immune system
1. Leukocytes
2. DCs –> APCs
3. Adaptive cells
What does Th1 promote?
- Macrophage activity
What dos Th2 help with?
- Isotpye switching of Igs
What does Th17 help with?
- Recruiting cells to the infection site
Which Th cell is good for EXTRACELLULAR pathogens?
- Th17
Which Th cell is good for INTRACDELLULAR pathogens?
- Th1
What does it mean mean if the R0 is HIGH in terms of vaccine coverage to achieve control/eradication?
- Vaccine coverage (and efficacy) must be HIGH to achieve control eradication
Which two diseases have high R0s?
- Measles and Pertussis (both 92-95%)
What does herd immunity only apply for?
- Diseases that are spread from human-human (e.g. polio, measles)
What does herd immunity reduce?
- The available pathogen reservoir for further infection
In HIV does the reverse transcriptase have a proofreading function?
- NO
Does HIV-1 undergo extremely rapid rates of mutation?
- YES
Does the HIV-1 virus generate incredible diversity in the population AND within the individual?
- YES
What is the most abundant antigen on the HIV virus surface?
- Env –> mutates at incredibly high rate
In the HIV virus, do certain sites on Env have to be conserved to enable the virus binding and entry into the cells?
- YES
- CD4 binding site is conserved
Can HIV be treated by passive immunisation?
- YES
- Make antibodies for the CD4 binding site that neutralise array of HIV-1 viruses
In the HIV-1 virus vaccination, what can we use as the antigen?
- The CD4 binding site alone as the antigen (focus the immune response on the CD4 binding site)
What was the smallpox vaccination based on?
- That milkmaids has nice skin and didn’t get smallpox BUT did get cowpox –> vacca–> cow in latin
When was vaccination formally tested by Edward Jenner in?
- 1796
What did Edward Jenner do in terms of Smallpox?
- took cowpox from milkmaid
- Inoculated arm of kid
- Kid was protected from variolation and smallpox
For pertussis is the acellular vaccine a subunit vaccine or a inactivated vaccine?
Subunit vaccine
Is the whole cell pertussis vaccine a subiunit vaccine or an inactivated vaccine?
Inactivated vaccine
What type of vaccine is DTaP and which vaccine class does it belong to?
- Toxoid vaccine
- Part of the subunit vaccine class
Do live attenuated vaccines need additional adjuvants?
- NO
- Because they are live, whole viruses or bacteria they INTRINSICALLY contain or generate a number of ‘danger’ signals
What is the format of live attenuated vaccines?
Models”real infection” with replciation, multiple antigens, and adjuvant signals
What are the pros of live attenuated vaccines?
- Induces strong, lifelong immunity for antibody and T cells (vaccina)
What are the cons of live attenuated vaccines?
- Can cause more severe side-effects (vaccina)
- Can cause disease in immunocompromised people (BCG-TB vaccine)
- Chance of reversion of virulence (tOPV-polio vaccine)
What is the format of the killed and inactivated vaccine?
Multiple antigens and adjuvant sigals
What are the pros of killed inactivated viruses?
- Can induce strong, long lasting immunity
What are the cons of killed inactivated viruses?
- Reliant on effective inactivation (historical accidents)
- Can be more reactogenic (DTwP)
What is the format of subunit vaccines?
- Reduced selection of antigens and adjuvant signals
What are the pros of subunit vaccines?
- Very safe
- Can induce antibody immunity
What are the cons of subunit vaccines?
- Not good for T cell immunity
- Immunity may wane or be less effective at preventing infection
- Requires multiple shots (DTaP)
What are needle free vaccines?
- Thousands of microscopic projections dry coated with live or subunit vaccines
- Applied to skin and penetrate to where immune cells reside
- NO refrigeration!
- Effective in animal trial
What does immunological memory require? (3 things)
- Innate immune responses
- Antigen uptake and presentation to trigger
- Adaptive immune responses (B and T cells)
What does vaccination and immunological memory INCREASE?
-Increases the NUMBER of memory B or T cells that recognise a specific antigen (on specific pathogen)
What does vaccination and immunological memory DECREASE?
-Amount of signal needed to activate antigen-specific memory B and T cells
what is passive immunity and give examples? (when is it given, what is it, what duration does it have?)
- Transfer of Ig from an immune –> non-immune individual/organism
- Ideally given BEFORE infection (otherwise won’t develop memory)
- IMMEDIATE onset of protection
- LIMITED DURATION (months, Ig turnover)
e. g. Maternal antibodies (Placenta IgM or colostrum in breast milk, also treatment for HIV-1)
What is active immunity and give example? (duration, when is it given, what is it?)
- Generated by the host
- Induction of a specific, protective immune response by EXPOSURE to antigen (i.e. vaccination)
- Must be give WELL IN ADVANCE of infection
- Protective immune response takes WEEKS to develop
- PROTRACTED DURATION (years, eventual turnover of memory B and T cells)
e. g. Vaccination, microbial infection
What is passive immunity good for?
- Toxins–> snake bite, tetanus, rabies, gas gangrene
- Outbreaks where antibody can provide protection to survivors BUT vaccines are not developed
- E.g. Performed during Ebola outbreaks
- Transfer serum from survivors (containing Ig) to individuals exposed to virus
What is active immunty good for? (with examples)
- Inducing WIDESPREAD immunity in the community to HIGHLY transmissible diseases
- Influenza, measles, HPV (Human Papolloma Virus)
What is the main aim of vaccination?
- Erdadication of disease from population
What are the three smaller aims of vaccination?
- Prevention of infection –> “efficacy” of the vaccine
- Reduce the infection load/severity (vaccinated people less likely to need hospitalisation)
- Reduce infection transmission (fewer people are infected at the population level)
What two things does herd immuntiy do?
- Limits the availability of the pathogen to infect and spread within a population
- Protects those who can’t be vaccinated (“community immunity”)