13.2 Vaccines

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Questions and Answers

What is the primary purpose of site-directed mutagenesis in vaccine development?

To remove genes responsible for virulence (correct)

To enhance pathogen replication

To create live attenuated vaccines

To increase the virulence of pathogens

Which method is NOT typically used to inactivate microorganisms for killed vaccines?

Selective breeding (correct)

Chemicals

Radiation

Heat

How do toxoid vaccines induce an immune response?

By causing direct cellular damage

By replicating pathogens inside the body

By producing live pathogens

By inducing neutralizing antibodies against inactivated toxins (correct)

What is the role of bacterial polysaccharides in vaccine development?

They prevent phagocytosis by immune cells (B) Signup and view all the answers

In recombinant vaccines, what is produced through genetic engineering?

Immunogenic proteins (C) Signup and view all the answers

What was the key observation that led Edward Jenner to develop the smallpox vaccine?

Milkmaids rarely contracted smallpox. (B) Signup and view all the answers

Which of the following best defines passive immunity?

Immunity obtained by maternal antibodies or antiserum. (A) Signup and view all the answers

What is a major disadvantage of passive immunity?

It may lead to hypersensitivity reactions. (C) Signup and view all the answers

What historical event marked the beginning of modern vaccination?

The introduction of cowpox to treat smallpox. (C) Signup and view all the answers

During which condition is passive immunity particularly necessary?

Primary or secondary immunodeficiency. (B) Signup and view all the answers

What term is derived from the Latin word for cow and is associated with vaccination?

Vaccus. (D) Signup and view all the answers

Which of the following infections is passive immunity typically administered for in humans?

Diphtheria. (D) Signup and view all the answers

What role do naive T and B cells play in vaccination?

They are crucial for forming immunity memory. (C) Signup and view all the answers

What is primarily harvested from the serum of hyperimmunized animals for immunizations?

Immunoglobulins (A) Signup and view all the answers

What type of vaccines is most likely to induce a long-lasting immune response?

Live-attenuated vaccines (C) Signup and view all the answers

What is a major consideration when selecting a vaccine to induce active immunity?

Induction of immunological memory (B) Signup and view all the answers

Which method is NOT used to achieve the attenuation of a pathogen?

Heating to destroy all proteins (A) Signup and view all the answers

Which type of vaccination method involves the use of genetically modified organisms?

Naked DNA vaccines (D) Signup and view all the answers

How do live-attenuated vaccines primarily provide long-term immunity?

By replicating inside the human body (C) Signup and view all the answers

What is a characteristic feature of subunit/component vaccines?

They include only specific parts of the pathogen (D) Signup and view all the answers

Which characteristic is NOT typical of inactivated vaccines?

They may cause disease (C) Signup and view all the answers

What is the first step in the process of creating naked DNA vaccines?

Identifying the gene encoding the immunogenic proteins (C) Signup and view all the answers

How do adjuvants enhance immune responses to antigens?

By facilitating or enhancing immune response to the antigen (A) Signup and view all the answers

What role does the recombinant virus play in vector vaccines?

It carries a non-infectious immunogenic protein (D) Signup and view all the answers

Which of the following is NOT a commonly used adjuvant?

Petroleum jelly (B) Signup and view all the answers

What is the main purpose of DIVA vaccines?

To differentiate vaccinated from naturally infected animals (D) Signup and view all the answers

How do immune stimulating complexes (ISCOMs) function as adjuvants?

They enhance recognition by antigen-presenting cells (APCs) (A) Signup and view all the answers

What is the effect of adding an adjuvant that mimics PAMPs or DAMPs in vaccines?

It enhances immune stimulation by activating APCs (B) Signup and view all the answers

Which of the following describes antigen-depot formation as a mechanism of adjuvants?

Antigens are slowly released into the intravascular tissue (D) Signup and view all the answers

What is the main characteristic of killed vaccines?

They are made from inactivated viruses or dead bacteria. (A) Signup and view all the answers

What role do polysaccharides play in bacterial component vaccines?

They enable efficient phagocytosis by opsonization. (A) Signup and view all the answers

How do toxoid vaccines stimulate an immune response?

By inactivating toxins while retaining their ability to provoke an immune response. (A) Signup and view all the answers

What distinguishes recombinant vaccines from other vaccine types?

They use cloned genes to express immunogenic proteins. (B) Signup and view all the answers

What is a key benefit of using genetic engineering in vaccine development?

It allows for the production of safer and more effective vaccines. (B) Signup and view all the answers

What is the primary reason for administering passive immunity?

To provide immediate protection during an infection (D) Signup and view all the answers

Which historical figure is credited with the development of the smallpox vaccine?

Edward Jenner (C) Signup and view all the answers

Which of the following infections typically requires passive immunity in humans?

Diphtheria (C) Signup and view all the answers

What is the significance of maternal antibodies in neonatal immunity?

They offer immediate but temporary immunity. (B) Signup and view all the answers

What commonly triggers the production of hyperimmune serum?

Deliberate immunization with a pathogen (D) Signup and view all the answers

How did Edward Jenner contribute to the field of immunology?

He introduced the concept of vaccination through cowpox. (C) Signup and view all the answers

What is the Latin origin of the term 'vaccination'?

Vacca - cow (D) Signup and view all the answers

What is the main purpose of cleaving immunoglobulins to Fab´2?

To reduce their immunogenicity. (C) Signup and view all the answers

Which type of immune response is primarily induced by vaccines to provide long-term immunity?

Cellular immune response. (B), Humoral immune response. (D) Signup and view all the answers

What is an essential factor when selecting a vaccine to ensure it provides long-term protection?

If the vaccine induces immunological memory. (A) Signup and view all the answers

How do live-attenuated vaccines achieve their effectiveness?

By replicating a non-virulent form of the pathogen. (C) Signup and view all the answers

What is the process of passaging in relation to vaccine development?

Culturing pathogens in conditions that reduce virulence. (A) Signup and view all the answers

What type of vaccines are primarily effective due to the efficient presentation of antigenic epitopes?

Live-attenuated vaccines. (B) Signup and view all the answers

Which of the following is a major advantage of live-attenuated vaccines over inactivated vaccines?

Ability to generate a stronger immune response. (C) Signup and view all the answers

What characteristic of inactivated vaccines is key in their development?

They utilize heat-killed or chemically inactivated agents. (C) Signup and view all the answers

What are the benefits of using adjuvants in vaccination?

They enhance the immunogenicity of certain antigens. (B) Signup and view all the answers

How do vector vaccines elicit an immune response?

They use a virus vector to deliver immunogenic proteins. (B) Signup and view all the answers

What is the primary function of DIVA vaccines?

To differentiate between vaccinated and naturally infected animals. (A) Signup and view all the answers

Which mechanism describes antigen-depot formation as related to adjuvants?

Slowly dissipating into intravascular tissue. (D) Signup and view all the answers

What type of vector is mostly used in vector vaccines?

Virus vector. (A) Signup and view all the answers

Which of the following correctly describes the role of dendritic cells in vaccine response?

They present antigen to lymphocytes, triggering an immune response. (D) Signup and view all the answers

Which of the following substances is commonly used as an adjuvant?

Alum (aluminum salts). (A) Signup and view all the answers

What is the first step in creating naked DNA vaccines?

Cloning the gene encoding immunogenic proteins. (A) Signup and view all the answers

Study Notes

Vaccination

Vaccination is not for financial gain by veterinarians.
Young animals of most species are vulnerable to infectious diseases.
They lack memory lymphocytes.
Infectious diseases cause significant mortality, even in developed countries.
Immunizations help prevent deaths caused by infectious diseases.
Vaccination is an important medical decision based on knowledge of the presence of an infectious agent in the animal herd (not every animal requires a vaccine).

History of Vaccination

Edward Jenner pioneered modern vaccination in 1796, targeting smallpox.
Jenner observed that milkmaids were rarely affected by smallpox.
He theorized cowpox conferred immunity against smallpox.
Jenner collected cowpox pus and inoculated a boy (James Phipps).
Phipps survived subsequent smallpox exposure.
"Vaccination" was derived from the Latin word "vaccus," meaning cow.

Essentials of Useful Vaccines

Safe vaccines do not cause illness or mortality in most recipients; side effects are minimal.
Protective vaccines prevent or lessen illness caused by pathogens.
Long-lasting effects of vaccines confer sustained resistance against pathogens.
Vaccines induce antibodies that respond to specific antigens, promoting sustained defense.
Vaccines stimulate cell-mediated and humoral immunity, targeting intracellular pathogens, notably viruses.
Vaccines are generally inexpensive, stable, and easily administered.

Types of Immunity

Passive Immunity:
- Transfer of maternal antibodies to newborns.
- Administration of serum globulin fraction (antiserum or pure antibodies processed via ethanol precipitation).

When is Passive Immunity Necessary?

Primary or secondary immunodeficiencies.
Cases where active immunity is impossible or insufficient.
Infections requiring rapid antibody transfer for protection (e.g., tetanus prevention in unvaccinated individuals).

Disadvantages of Passive Immunity

Elevated risk of hypersensitivity types I and III.
Temporary immunity; does not generate lasting memory.

How is Hyperimmune Serum Produced?

Horses, goats, or sheep are immunized.
Serum is collected from hyperimmunized animals.
Immunoglobulins are extracted from the serum.
Processing (e.g., cleavage to Fab'2) prevents immunogenicity.

Active Immunity

Acquired through infection with a pathogen.
Vaccination: attenuated, inactivated, subunit, recombinant vaccines.
Active immunity aims to provide long-term immunity.
T and B cells generate a memory response for sustained protection.

Considerations for Selecting a Vaccine

Measured immune responses do not always correlate with protective efficacy.
Vaccines must induce immunological memory for long-term protection.

Types of Vaccines

Live-attenuated vaccines;
Heat-killed/inactivated vaccines;
Subunit/component vaccines;
Toxoid vaccines;
Conjugate vaccines;
Recombinant vaccines;
Naked DNA vaccines;
Vector vaccines

Live-Attenuated Vaccines

Live pathogens, non- or less virulent, are employed as vaccines.
Replication enhances antigen quantity and improves immune response.
Antigenic epitopes are efficiently presented to T and B cells.

How is Attenuation Achieved?

Passage:
- Culturing virulent pathogens in unsuitable conditions reduces virulence and infectiousness (canine parvovirus; viral attenuation by lowering temperature).
Genetic Engineering:
- Modifying virulence genes through site-directed mutagenesis eliminates virulence factors.

Killed Vaccines

Inactivated viruses, bacteria, etc.
These agents are incapable of causing disease.
Immunogenicity is retained.
Methods for inactivation/killing include heat, chemicals, and radiation.

Subunit or Component Vaccines

Purified antigens of pathogens.
Toxoids: inactivated toxin proteins that trigger neutralizing antibodies. (e.g., tetanus, diphtheria).

Bacterial Polysaccharides

Polysaccharide coatings on bacterial cell surfaces.
Pathogenicity depends on phagocytosis inhibition.
Antibodies can neutralize bacteria by enhancing neutrophil and macrophage phagocytosis.

Recombinant Vaccines

Cloning and expression of immunogenic proteins in prokaryotic or eukaryotic cells generate antigens.
Viral proteins are common examples.

Naked DNA Vaccines

Inserting the gene for immunogenic proteins from a pathogen into a plasmid vector.
Injection of this plasmid DNA into animals leads to protein synthesis.
Dendritic cells present the antigen to lymphocytes triggering a robust immune response.

Vector Vaccines

Cloning and insertion of an immunogenic protein gene into a viral vector (e.g., vaccinia virus or adenovirus).
Vector, carrying the inserted gene, is delivered to animals.
Recombinant viral infection generates an immune response without causing disease.

Adverse Consequences of Vaccination

Vaccine reactions can include errors in manufacture or administration, contamination, toxicity, hypersensitivity, neurological reactions, and foreign body reactions.
Additional adverse reactions include inflammation, fever, pain, and potentially fatal outcomes like immunosupression and clinical disease in animals.

Ten Basic Principles of Vaccination

Vaccination is a medical decision based on risk, not every animal requires every vaccine.
Core vaccines address common, harmful diseases; non-core vaccines target diseases with risk-benefit considerations.
Vaccines should be given to most animals within a population to generate herd immunity.
Maternal antibodies (MDA) can interfere with vaccination in young animals, requiring booster vaccinations.
Adult animals require immunization according to vaccine duration.
Pregnant animals may be vaccinated when supported by data.
Ill or immunosuppressed animals should not be vaccinated.
Veterinarians should decide appropriate vaccines for individual cases.
Vaccination data sheets should be understood.
Vaccination documentation should be maintained.

DIVA vaccines (Marker vaccines)

Diagnosis of infections based on serum antibodies.
Distinguish naturally induced immune responses from those triggered by vaccination.

Adjuvants

Some antigens require adjuvants to enhance immunogenicity and trigger a more robust immune response.
Adjuvants facilitate the immune response to antigens.

Commonly Used Adjuvants

Liposomes;
Microspheres;
Immune-stimulating complexes;
Minerals (aluminum salts);
Oil-in-water or water-in-oil emulsions;
PRR agonists.

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Test your knowledge on vaccine development and immunology with this quiz. Explore various types of vaccines, their mechanisms, and historical developments in vaccination. Perfect for students and enthusiasts in the field of microbiology and immunology.