immunisation CMB2004!!!!!!!!!

Question 1

What are the effects of Interferon Gamma (IFN-γ)?

Answer 1

Secreted by: CTLs, NK cells, and other cells.
MHC I expression: Enhances expression of MHC I by activating the IFN-γ receptor, leading to transcription effects on the MHC I locus.
More MHC I: Increases the number of sites for TCR recognition, enhancing T cell activation and antigen presentation.
NK cell activation: Enhances NK cell function and ability to kill cells lacking MHC I (missing self).
Dual role: Directly activates NK cells (via receptors like NKG2D) to improve their killing ability.
Balancing act: IFN-γ helps CTL and NK cells but does so in different ways.

Question 2

What are the characteristics of passive immunity?

Answer 2

Short-lived: Half-life of IgG is about 3 weeks.
Infants: Hypogammaglobulinemia occurs as maternal IgG declines.
Immunodeficiency treatment: IVIgG administered every 2-4 weeks.
Example: Tetanus antitoxin provides temporary protection.

Question 3

What is active immunity?

Answer 3

Immunological memory: Based on the body’s memory of past infections.
Primary vs. Secondary response: Secondary responses are faster, stronger, and potentially more specific (higher affinity antibodies).

Question 4

What is herd immunity and why is it important?

Answer 4

Protection of individuals and populations: Herd immunity reduces disease spread when a majority of the population is immune.
Thresholds: Different diseases have different herd immunity thresholds (e.g., 75-80% for SARS-CoV-2, 83-94% for measles).

Question 5

What are the key requirements for an effective vaccine?

Answer 5

Safe, high protection, long-lasting protection.
Induces the right type of immune response (local/systemic, antibody/cell-mediated).
Low cost, stable, easy to administer, minimal side effects.

Question 6

What are the five main types of vaccines?

Answer 6

1. Inactivated (dead) organisms (e.g., Salk polio vaccine).
2. Attenuated (live but weakened) organisms (e.g., Yellow fever).
3. Subunit vaccines (e.g., Hepatitis B).
4. Toxoid vaccines (e.g., Tetanus).
5. Conjugate vaccines (e.g., Streptococcus pneumoniae + diphtheria).

Question 7

What are the pros and cons of live, attenuated vaccines?

Answer 7

Pros: Single dose effective, may induce both local and systemic immunity, induces the correct immune response.
Cons: Risk of reversion to virulence, possible contamination, causes disease in immunocompromised hosts, susceptible to inactivation.

Question 8

What are subunit and toxoid vaccines?

Answer 8

Subunit vaccines: Contain isolated antigens (e.g., Hepatitis B surface antigen).
Toxoid vaccines: Contain inactivated toxins (e.g., Tetanus toxoid).

Question 9

What are conjugate vaccines and how do they work?

Answer 9

Definition: Polysaccharides from a pathogen’s capsule conjugated to a protein.
Example: Hib, Pneumococcal conjugate vaccine.
How it works: Converts thymus-independent antigens into thymus-dependent ones, allowing T cell help for better immune responses.

Question 10

What is reverse vaccinology?

Answer 10

: Whole genome screening to identify proteins that can be used for vaccines.
Example: Neisseria meningitidis group B vaccine developed using this method.

Question 11

What are adjuvants and how do they enhance vaccine responses?

Answer 11

Substances added to vaccines to enhance the immune response.
Functions: Provide a “depot,” activate dendritic cells, release cytokines, promote antigen uptake and cross-presentation.
Examples: Alum (commonly used), MF59, AS03, AS04.

Question 12

Why is inducing the “right” type of immune response important for vaccines?

Answer 12

HIV may require CTL responses.
Incorrect responses can be harmful: e.g., 1960s RSV vaccine caused worse outcomes in vaccinated children.

Question 13

What are the key facts about polio?

Answer 13

Enterovirus, primarily affects children under 5.
Transmission: Fecal-oral route.
Complications: 1/200 cases result in irreversible paralysis.
Vaccines: Global eradication effort launched in 1988; polio is nearly eradicated with Type 2 strain eradicated in 1999.

Question 14

What is notable about COVID-19 vaccine development?

Answer 14

Development happened rapidly, with 183 vaccines in clinical trials as of October 2023.
Types: mRNA vaccines (Pfizer/BioNTech, Moderna), viral vector vaccines (Oxford/AstraZeneca), protein subunit vaccines (Novavax), etc.
Global effort: Unprecedented vaccine development for a global pandemic.

Question 15

What is immunological memory and how does it relate to active immunity?

Answer 15

The ability of the immune system to remember previous encounters with pathogens, leading to faster and more robust responses.
Active Immunity: Exploits immunological memory through primary and secondary responses.
Secondary response: Faster, more potent, and more specific due to memory cells (e.g., memory B cells and T cells).

Question 16

What is hypogammaglobulinemia in infants and why does it occur?

Answer 16

Decline in maternal IgG, which provides temporary immunity.
Effect: Infants are more susceptible to infections until their own immune system becomes functional.

Question 17

How is IVIgG used in immunodeficiency?

Answer 17

Provides passive immunity to individuals with immunodeficiencies by administering IgG antibodies every 2-4 weeks.
Benefit: Helps maintain protective levels of antibodies, compensating for the body’s inability to produce them.

Question 18

What are the key facts about Measles and its vaccination?

Answer 18

Highly contagious viral disease causing rash, fever, ear infections, pneumonia, and sometimes fatal complications like SSPE (Subacute Sclerosing Panencephalitis).
Vaccine: MMR (Measles, Mumps, Rubella) vaccine introduced in 1988.
Herd immunity threshold: 83-94% of the population must be immune to prevent outbreaks.

Question 19

What caused the decline in MMR vaccine uptake?

Answer 19

A 1998 paper by Wakefield falsely linked the MMR vaccine to autism, leading to a decline in vaccination rates.
Consequence: Re-emergence of measles outbreaks due to reduced vaccine coverage.

Question 20

What are the characteristics of a safe vaccine?

Answer 20

The vaccine must not cause the disease it is protecting against.
Minimal Side Effects: Side effects should be mild and temporary.

Question 21

How should a vaccine provide long-lasting protection?

Answer 21

Longevity: A good vaccine should induce lasting immunity, with some vaccines requiring booster shots to maintain protective levels.
Memory Cells: Promotes the formation of memory B and T cells to recognize the pathogen in the future.

Question 22

What types of immune responses can vaccines induce?

Answer 22

Local vs. Systemic Response: Vaccines can induce immunity at the site of infection (local) or throughout the body (systemic).
Antibody vs. Cell-mediated Immunity: Some vaccines elicit an antibody response, while others (e.g., for viruses like HIV) may require a cell-mediated immune response.

Question 23

What is the BCG vaccine and how effective is it?

Answer 23

BCG Vaccine: Protects against tuberculosis, made from an attenuated strain of Mycobacterium bovis.
Effectiveness: It is not universally effective, particularly in adults, but is widely used in countries with high TB prevalence.

Question 24

Why is the polio vaccine considered one of the greatest successes in vaccination history?

Answer 24

Eradication Efforts: The World Health Assembly launched a global initiative in 1988 to eradicate polio, leading to a significant reduction in cases.
Success: Polio type 2 was eradicated in 1999, and type 3 was last reported in 2012. Cases have drastically reduced, with only a few remaining pockets of infection.

Question 25

What are some examples of subunit vaccines and how do they work?

Answer 25

Examples: Hepatitis B vaccine (surface antigen), Pneumococcal vaccine (pneumococcal polysaccharide).
Mechanism: Contain only isolated antigens to stimulate an immune response, without using live pathogens.

Question 26

What are toxoid vaccines and what is their purpose?

Answer 26

Vaccines made from inactivated bacterial toxins (toxins that have been rendered non-toxic).
Examples: Tetanus, Diphtheria.
Purpose: Induce immunity to the toxin rather than the bacteria itself.

Question 27

How is vaccine safety monitored after approval?

Answer 27

Post-marketing Surveillance: Vaccines are monitored for side effects and long-term safety using systems like VAERS (Vaccine Adverse Event Reporting System).
Importance: Ensures that any rare or long-term side effects are detected and addressed.

Question 28

What were the key strategies used in the global polio eradication campaign?

Answer 28

Global Coordination: Coordinated efforts from the WHO and other health organizations.
Routine Immunization: Administering oral polio vaccine (OPV) to all children, especially in high-risk regions.
Surveillance and Response: Active surveillance to detect outbreaks and rapid response to stop transmission.

Question 29

: What are some examples of adjuvants used in human vaccines?

Answer 29

Alum: Commonly used, helps promote antibody responses.
MF59: Squalene-based adjuvant used in some flu vaccines.
AS03: Includes squalene and vitamin E, used in H1N1 flu vaccines.

Question 30

What are examples of next-generation vaccines?

Answer 30

mRNA Vaccines: Pfizer/BioNTech and Moderna COVID-19 vaccines.
Viral Vector Vaccines: Oxford/AstraZeneca COVID-19 vaccine.
Protein Subunit Vaccines: Novavax COVID-19 vaccine