Vaccination Effectiveness and Herd Immunity

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Questions and Answers

What is the primary function of hemolysins in bacteria?

To enhance nutrient absorption

To promote muscle contraction

To evade the immune system

To facilitate iron acquisition (correct)

Which of the following is NOT a characteristic of A-B (5) toxins?

Beta protein binds to the cell surface

They directly kill host cells (correct)

They can subvert cellular functions

Alpha protein cleaves and enters the cell

What is ADP ribosylation?

An enzymatic breakdown of toxins

A pretranslational modification of proteins

A posttranslational modification affecting host proteins (correct)

A process of cell division

What role do proteases play in bacterial pathogenesis?

Digesting host macromolecules to acquire nutrients Signup and view all the answers

Which type of toxin is primarily involved in food poisoning and is associated with the bacterium Clostridium botulinum?

Exotoxin Signup and view all the answers

How does Tetanus toxin affect neurotransmitter release?

It inhibits the release of inhibitory neurotransmitters Signup and view all the answers

Which of the following is a characteristic feature of cytotoxins?

They are pore-forming and destroy host cells. Signup and view all the answers

Which bacterial toxin is associated with gangrene due to its lipase activity?

Alpha toxin of Clostridium perfringens Signup and view all the answers

What is the notable action of the toxin cereulide?

It collapses mitochondrial membrane potential. Signup and view all the answers

Which virulence factor allows bacteria to hide from the immune system by forming a clot?

Coagulase Signup and view all the answers

What is a common feature of bacterial toxins regarding nucleotide transfer?

They typically involve NAD in modifications Signup and view all the answers

Which toxin is known to degrade SNARE proteins to cause paralysis?

Clostridial protease Signup and view all the answers

Which type of secretion system in proteobacteria is known for delivering effector proteins directly into the host cell cytoplasm without needing special receptors?

Type III secretion system Signup and view all the answers

What is the primary function of exotoxins in pathogenic bacteria?

Causing direct damage or functional inhibition in host cells Signup and view all the answers

Which type of exotoxin is characterized by being enzymes that can damage host tissues?

Proteases Signup and view all the answers

Which of the following statements about endotoxins is correct?

They stimulate a strong immune response when released. Signup and view all the answers

What mode of action is common among A-B toxins?

They modify the activity of host proteins after uptake. Signup and view all the answers

What defines the 'invasion' process in the context of microbial infection?

The microbe enters cells or tissues of the host Signup and view all the answers

What role does the capsule play for bacteria such as Acinetobacter spp. and Klebsiella pneumoniae?

It contributes to the bacteria's virulence by preventing phagocytosis Signup and view all the answers

Which of the following is least likely to cause food poisoning?

Clostridium tetani Signup and view all the answers

Which of the following is NOT a known example of a cytotoxin?

Cholera toxin Signup and view all the answers

What is the primary purpose of vaccines in relation to B-cells and T-cells?

To exploit memory functions for future exposure Signup and view all the answers

Which of the following diseases requires the highest herd immunity threshold?

Measles Signup and view all the answers

What does the Basic Reproduction Number (R0) indicate?

The expected number of people infected by one infected person Signup and view all the answers

What type of relationship is described by a parasite?

A long-term relationship that ideally doesn't harm the host Signup and view all the answers

How is the efficacy of a vaccine calculated?

By calculating the difference in infection rates between vaccinated and unvaccinated groups Signup and view all the answers

What does the term 'pathogenicity' refer to?

The degree of harm caused by an organism to a host Signup and view all the answers

Which of the following statements about herd immunity is true?

Partial immunization of a population protects those who cannot be vaccinated. Signup and view all the answers

The spike protein of SARS-CoV-2 serves as what in the context of vaccination?

An antigen used to prime the immune response Signup and view all the answers

What does LD50 measure in pathogenic organisms?

The lethal dose required to kill 50% of the test population Signup and view all the answers

Which of the following is considered an obligate pathogen?

Pseudomonas aeruginosa Signup and view all the answers

What are zoonotic diseases?

Diseases that can be transferred between animals and humans Signup and view all the answers

Which feature enhances the ability of microorganisms to adhere to body surfaces?

Cell secretions and external structures Signup and view all the answers

What is the primary means by which pathogens cause disease?

By adhering, overcoming barriers, multiplying, and disseminating Signup and view all the answers

Which of the following pathogens can be acquired through inhalation?

Legionella Signup and view all the answers

What does ID50 signify in the context of infectious diseases?

Number of cells required to colonize 50% of test subjects Signup and view all the answers

What type of pathogen does Myxococcus represent?

Predator Signup and view all the answers

Study Notes

Vaccination Wrap-up

Clinical trials are used to assess vaccine efficacy.
Efficacy is calculated as: (% unvaccinated infected - % vaccinated infected) / % unvaccinated infected.
This method compares infections in a control group (placebo) versus a vaccinated group.
For example, in one trial, 185 people in a placebo group developed Covid-19, compared to 11 in the vaccine group. This shows vaccine efficacy.

Daily Average Case Rate and Hospitalization Rate

Data (Figure 1) displays daily average case rates and seven-day cumulative hospitalizations by vaccination status.
Visualizations compare case rates and hospitalization rates between vaccinated and unvaccinated groups over time.
Shows trends in rates for vaccinated and unvaccinated groups post-vaccination rollout. The data suggests the overall impact of vaccination on the spread of disease.

Herd Immunity

Partial immunization of a population can protect the entire population including those unable to be vaccinated.
Shows diagrams illustrating how a contagious disease spreads when varying percentages of a population are immunized.
Describes situations where no one is immunized, some are immunized and most individuals are immunized, highlighting the containment of the contagious disease as a result of vaccination.

Basic Reproduction Number (R₀)

Reproduction Number (Ro) is the expected number of people that a single person with a disease will infect.
The values of Ro differ, based on the specific disease, ranging from 4 to 18 depending on a contagious condition.
Herd immunity thresholds also vary, indicating that different diseases require different percentages of the population to be immunized to achieve herd immunity. For instance, for measles, it's between 83-94%.

Summary of Vaccines

Vaccines utilize memory B- and T-cells.
Pathogen antigens prime the immune system for future exposures.
Antigens can be derived from whole cells or pathogen fragments (e.g., the SARS-CoV-2 spike protein).

Pathogenicity and Virulence Factors (34)

A visual image of a microscopic slide with bacteria is shown.
No other detailed information is provided.

Parasite/Pathogen/Predator

Pathogens cause disease, sometimes involving toxins.
Pathogenicity is the ability to cause disease through damage.
Parasites have long-term relationships with hosts. Predatory interactions involve rapid prey death.
Opportunistic pathogens cause disease when host barriers are compromised, and obligate pathogens need a host to survive.

Virulence

LD50 (Lethal Dose 50%) is a measurement of the pathogenicity of an organism, representing the number of cells needed to kill half the infected test population.
ID50 (Infectious Dose 50%) is the number of pathogen cells needed to infect half the test subjects.
Charts illustrate the variation in pathogenicity across different organisms using percentages of mice killed by different numbers of cells.

Bacteria of Virulence Factors (10)

Data tables and diagrams show different bacteria and their respective virulence factor values.
Provides a list of various bacteria and their corresponding values.

Food/Water Sources of Pathogens (12)

Food and water are potential sources of bacteria, such as E. coli, Salmonella, Listeria, Shigella, and Vibrio.
Inhalation can transmit pathogens such as Legionella and Klebsiella.
Wounds can introduce pathogens like Staphylococcus and Clostridium.

Zoonotic Diseases

Zoonotic diseases are those that spread between animals and humans, such as diseases acquired from consuming contaminated meat or animals.
No specific diseases are listed further.

To Cause Disease(s)

Pathogens attach to host cells and overcome barriers, such as cuts, ingestion, inhalation, or immune responses.
They find food, multiply, and kill the host cells.
Pathogens eventually spread to adjacent tissues, such as with diarrhea.

Virulence Factors - Adherence (17)

Adherence: enhancing the ability of microorganisms sticking to body surfaces.
This is mediated by external structures (pili, fimbriae, flagella, adhesins); additional resources include cell secretions (capsules, slime layers, or glycocalyx), biofilms (EPS) from cells.

Generalized vs. Specialized Virulence Factors: Adhesins (18)

General adhesion to surfaces is aided by surface structures (pili/fimbriae).
Some bacteria have specialty adhesion factors to stick to host cells.
Intimin is a surface protein of some pathogenic E. coli enabling adhesion to the intestine.
Example is Influenza virus and hemagglutinin

Capsule as a Virulence Factor(19)

Some bacteria (e.g., Acinetobacter, Haemophilus influenzae, Klebsiella pneumoniae, Streptococci) produce encapsulation.
Capsules are virulence factors enhancing bacterial survival as they shield the bacteria from immune surveillance..

Pathogenic E. coli and Vibrio cholerae (20)

Images show microscopic structures of pathogenic E. coli and Vibrio cholerae.
Visualizations/images show cellular structures under a microscope/electron microscope, with no further detail.

Virulence Factors-Invasion & Infection (21)

Invasion is the act of entering host cells or tissues for pathogens to facilitate their spread.
Infection involves the presence of a foreign microbe in or on the body but without necessarily causing diseases at that time.

Virulence Factors - Invasion/Infection (22)

Pathogenicity factors enhance how easily pathogens invade tissues and establish infections.
Enzymes disrupt tissue structures (e.g., hyaluronidase, collagenases, proteases).
Coagulase forms clots around the pathogen to evade immune defenses.

Virulence Factors - Toxins(23)

Toxins are substances that cause diseases.
There are three major toxin types: cytotoxins, AB toxins, and enzymes. Toxins can affect cells distant from the infection site.

Cytotoxins (24)

Cytotoxins kill host cells, as shown by the visual/diagram.
Example of an alpha toxin from Staphylococcus is shown/diagrammed, illustrating how it creates holes in a host's cell membrane.
Hemolysis is frequently tested using blood agar plates.

Pore-forming Cytotoxins (25)

Pore-forming cytotoxins release nutrients and aid host tissue penetration.
Examples of toxins include Hemolysins, some RTX-type toxins, and leukocidins.
Streptolysin is genetically regulated by iron starvation.

A-B Toxins(26)

A-B toxins have a beta component that promotes entry and an alpha component that enters host cells, disrupting normal functions (e.g., signal transduction, protein synthesis, and vesicle trafficking).
Beta components bind cells, while alpha components have diverse functions and effects.
Production of messengers like cAMP (e.g., cholera toxin) is a function of A-B toxins.

Nucleotide Transfer (27)

ADP ribosylation is a frequent modification of host proteins by bacterial toxins.
Examples include pertussis, cholera toxins, enterotoxigenic E. coli heat-labile toxin, and typhoid toxin.

Protein Structure and Function(28,29,30)

Protein function is altered with addition to nucleotides, which can activate or inhibit functions.

Proteases and Lipases (31)

Many pathogens use proteases and lipases to digest host macromolecules, aiding spread and nutrient acquisition.

Botox (32)

Botulinum toxin (Botox) is a clostridial protease that deactivates SNARE proteins. This prevents neurotransmitter release, leading to paralysis.
Tetanus toxin is also a clostridial protease that affects inhibitory neurons and decreases neurotransmitter release, causing muscle spasms).

Botox mechanism (33)

Diagrams illustrate the mechanism of botulinum toxin in damaging SNARE proteins, preventing neurotransmitter release, and causing muscle paralysis.

Endotoxin (34)

Endotoxins are released from dead bacteria and trigger a strong immune response in the host.
They are components of gram-negative bacterial cell walls.

Food Poisoning (35)

Cereulide is a rare toxin from Bacillus cereus that causes food poisoning.

Toxins Overview (36)

Endotoxins (LPS) are components of gram-negative bacterial cell walls.
Exotoxins are secreted proteins formed by live organisms, causing harm.
Examples of exotoxins are proteases, lipases, cytotoxins (pore-forming and others), and AB toxins (with an A subunit and B subunit).

Endocytosis Defect(37)

A question asks about toxins ineffective against cells deficient in endocytosis.

Secretion Systems in Proteobacteria (38)

Tat system exports proteins folded in the cytoplasm.
Type I–VI systems are for interactions with other cells and pathogenicity.
Outer membrane vesicles (OMVs) are also noteworthy.

Type III Secretion (T3SS)(39)

Diagrams illustrating a type III secretion system and how it delivers effector proteins from the pathogen to the host cytoplasm without the host requiring a receptor.
No dilution occurs in the delivery process.

Secretion Systems and Host Cell Reprogramming (40)

Effector proteins have diverse functions (e.g., target cell cytoskeleton reorganization, inhibition of phagocytosis).
The number of effector proteins varies between species (example values shown).

Summary(41)

Pathogens interact with physical, chemical, and microbiota barriers.
Pathogenicity factors such as attachment factors and enzymes that degrade barriers allow infection.
Numerous toxins cause host cell lysis or alter host cell function, potentially at various locations.

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Description

This quiz covers essential concepts related to the efficacy of vaccinations, including how clinical trials measure effectiveness and the impact of vaccination on daily case rates and hospitalizations. Additionally, it explores the concept of herd immunity and its significance in public health. Assess your understanding of these critical topics in vaccination science.