Immunology Study Guides 9-12

A vaccinated dam transfers protective antibodies to her newborn through colostrum. Which statement correctly describes immunity in the newborn?

It is passive immunity: protection is immediate but temporary, without recipient memory from antibody transfer alone.

Which feature most clearly distinguishes a modified-live vaccine from an inactivated whole-organism vaccine?

The modified-live organism retains the ability to replicate in a suitable host.

What is an important function of a vaccine adjuvant?

Enhancing antigen delivery and innate activation to support the adaptive response.

Which pairing correctly identifies a tetanus toxoid vaccine and tetanus antitoxin?

Toxoid: active immunity against toxin; antitoxin: passive antibody.

What does a recombinant protein subunit vaccine deliver?

A selected protein antigen

What does a recombinant viral vector do?

Delivers a gene so host cells make antigen

What do DNA and RNA vaccines have in common?

Both provide instructions for making antigen.

Which statement best describes why a vaccine may be formulated for intranasal administration?

It can promote local mucosal immunity, including IgA, near a portal of entry.

Where is vaccine mRNA translated into protein?

Cytoplasm

Why do killed vaccines often need adjuvants and multiple initial doses?

They cannot amplify antigen by replication.

Under the AAHA canine guidelines with the 2024 update, which set contains only core vaccines for dogs?

Distemper, adenovirus, parvovirus, rabies, and leptospirosis.

Which diseases are targeted by the feline FVRCP combination?

Feline herpesvirus-1 disease, calicivirus disease, and panleukopenia.

How do the 2020 AAHA/AAFP guidelines classify FeLV vaccination?

Core for cats younger than 1 year; continued adult vaccination depends on exposure risk.

After the kitten FVRCP series, the 2020 guidelines support a follow-up dose at what age?

About 6 months

Which statement correctly distinguishes vaccine efficacy from duration of immunity (DOI)?

Efficacy measures reduction in a defined disease outcome; DOI concerns how long protection lasts.

A puppy received distemper-adenovirus-parvovirus vaccine at 8 and 12 weeks. Why is a further dose at 16 weeks or later important?

Maternal antibody may block earlier priming, even after falling below the level needed to protect against disease.

A canarypox-vectored feline vaccine expresses its antigen inside feline cells but does not produce new infectious canarypox particles in the cat. Which interpretation is best?

Intracellular antigen expression can support MHC-I presentation even without productive vector replication.

A healthy 2-year-old dog has never received a leptospirosis vaccine. According to the AAHA 2024-updated table, what is the recommended initial plan?

Two doses 2-4 weeks apart, followed by a dose within 1 year and annual revaccination thereafter.

A cat has a 1.5-cm injection-site mass that is enlarging 6 weeks after vaccination. Which action best follows the 3-2-1 rule?

Arrange investigation and appropriately planned biopsy because continued growth beyond 1 month meets a criterion.

Several vaccinated adult dogs become ill. Records show an incomplete primary series in one dog and a storage-temperature excursion affecting vaccines given to others. What is the best interpretation?

Incomplete immunization and reduced vaccine potency are plausible causes; review the program before assigning a cause.

A puppy receives its first rabies vaccination at the product's labeled minimum age, using a product labeled for 3-year protection. Which statement matches the lecture's U.S. schedule?

Give the first booster 1 year after the initial dose; later intervals follow the label and applicable law.

Why might a veterinarian favor killed over modified-live vaccine in an immunocompromised animal?

Killed organisms cannot replicate in the animal.

Two vaccines are called recombinant: one delivers protein; the other uses a vector. What differs?

Ready-made antigen versus antigen made in host cells

Compare a protein subunit vaccine with an mRNA vaccine. Which has a direct route to intracellular antigen production and MHC-I presentation?

The mRNA vaccine

Which finding most strongly suggests an inherited immunodeficiency in a puppy?

Recurrent infections beginning early in life

Which description best distinguishes secondary from primary immunodeficiency?

It results from an acquired influence on immune function

A defect in V(D)J recombination is most likely to compromise which process?

Generation of diverse B- and T-cell receptors

Which pathway most directly links prolonged stress to secondary immunosuppression?

Increased corticosteroid activity suppresses immune-cell responses

Which mechanism explains recurrent bacterial infections in leukocyte adhesion deficiency?

Neutrophils fail to migrate from blood into tissues

During malnutrition, which change links loss of body fat to altered immune function?

Lower leptin production and reduced macrophage and Th1 stimulation

Which defect is characteristic of trapped-neutrophil syndrome in Border Collies?

Impaired release of neutrophils from marrow

Which combination is most characteristic of Chediak-Higashi syndrome?

Abnormal granules and partial depigmentation

Which change is most consistent with immunosenescence?

Reduced primary responses with some memory retained

A young dog has recurrent bacterial infections, marked circulating neutrophilia, and little neutrophil accumulation in infected tissues. Which defect best explains the findings?

Deficient CD18-mediated leukocyte adhesion

A cat develops recurrent opportunistic infections after a prolonged viral illness. Which interpretation is most appropriate?

An acquired infection-associated immune defect

Two young dogs have recurrent bacterial infections. Dog A has marked neutrophilia and poor neutrophil tissue recruitment; Dog B has neutropenia due to poor marrow release. Which pairing is most consistent?

Dog A: CD18 deficiency; Dog B: VPS13B defect

Why can healthy animals generate self-reactive lymphocytes during development?

Receptor rearrangement creates specificities without regard to self

Where does central tolerance of developing T cells principally occur?

Within the thymus during T-cell maturation

Which mechanism is an example of peripheral rather than central tolerance?

Suppression of autoreactive T cells by Tregs

What is the principal contribution of AIRE to self-tolerance?

Promoting tissue-restricted antigen expression in thymus

Which event best illustrates molecular mimicry?

A microbial epitope cross-reacts with a host epitope

Which event best illustrates epitope spreading?

An autoimmune response broadens to additional self epitopes

Which event best illustrates bystander activation?

Inflammation activates autoreactive cells near an infection

What is meant by an immune-privileged site?

A site where immune access or responses are restricted

Which process changes antigen specificity during B-cell central tolerance?

B-cell receptor editing

Which cell population is most directly associated with active suppression of autoreactive T cells?

Regulatory T cells

Which mechanism commonly contributes to oral tolerance to soluble dietary antigens?

Regulatory responses to antigens encountered in the gut

Why is maternal immune tolerance important during pregnancy?

It limits destructive responses against fetal-associated antigens

Which mechanism can eliminate activated lymphocytes after repeated antigen stimulation?

Activation-induced cell death

Which factor may influence susceptibility to autoimmune disease?

Host genetics and microbial exposures

How can autoimmune disease produce tissue injury?

Through antibody- or T-cell-mediated hypersensitivity mechanisms

After an infection, a dog develops antibodies that bind both microbial and host tissue epitopes. Which mechanism is most consistent?

Molecular mimicry

A tissue injury releases previously sequestered host proteins, followed by an autoimmune response. Which mechanism most directly initiates this response?

Loss of antigen segregation

An autoimmune response initially targets one self epitope but later recognizes several epitopes within the damaged tissue. What best explains this change?

Epitope spreading

A genetic defect prevents thymic expression of tissue-restricted antigens. Which consequence is most directly predicted?

Escape of some autoreactive T cells into the periphery

Following infection, a patient develops organ-specific autoimmunity. Early antibodies cross-react with microbial proteins; months later, antibodies target additional host epitopes. Which sequence best fits?

Molecular mimicry followed by epitope spreading

Which combination provides the host’s first line of defense against bacterial invasion?

Intact epithelium, mucus, ciliary clearance, and antimicrobial substances

How does the normal microbiota help protect the host against bacterial pathogens?

It competes for nutrients and attachment sites and can produce inhibitory substances.

After bacteria breach an epithelial barrier, how do resident sentinel initiate a protective response?

They recognize microbial patterns and release cytokines and chemokines.

Which host response most effectively promotes clearance of extracellular bacteria in infected tissue?

Complement activation, opsonization, and phagocytosis by neutrophils and macrophages

How do Th17 cells contribute to host protection against extracellular bacteria at mucosal surfaces?

They promote neutrophil recruitment and epithelial antimicrobial defenses.

A host develops widespread inflammation after exposure to Gram-negative bacterial endotoxin. Which mechanism best explains this response?

Recognition of LPS through the TLR4 receptor complex triggers inflammatory signaling that can become systemic.

Which antibody action most directly protects the host against an exotoxin-producing bacterium’s toxin?

Binding the toxin and blocking its attachment to or action on host cells

How do bacterial superantigens cause an unusually strong host response?

They link MHC II and particular T-cell receptor Vβ regions outside conventional peptide recognition, activating many T cells.

A bacterium survives inside macrophage vesicles. Which adaptive response most directly enhances host protection?

Th1-derived IFN-γ increasing macrophage antimicrobial activity

Early in an intracellular bacterial infection, which interaction helps the host control infection before a strong adaptive response develops?

Macrophages and dendritic cells produce IL-12, stimulating NK-cell IFN-γ production and macrophage activation.

Which comparison correctly matches the bacterial threat with the host’s principal protective mechanism?

Extracellular bacteria—antibodies, complement, and phagocytes; bacteria persisting in macrophage vesicles—Th1-mediated macrophage activation; secreted exotoxins—neutralizing antibodies

How do type I interferons help limit viral infection?

They induce antiviral proteins in infected and neighboring cells.

Which statement correctly compares NK cells and CD8 cytotoxic T cells?

NK cells respond to activating and inhibitory signals, whereas CD8 T cells recognize specific viral peptides on MHC I.

Which scenario illustrates antibody-dependent cellular cytotoxicity (ADCC)?

An NK cell binds antibodies coating an infected cell and kills that cell.

Which statement best describes the response to a primary viral infection?

Interferons and NK-cell activity generally occur early, followed by developing antibody and T-cell responses.

In the 3-2-1 rule. for monitoring injection sites in cats, what does the “3” refer to?

any lump present for more than 3 months after vaccination should be evaulated

What is the 3-2-1 rule for cat vaccination?

• 3 — The lump is still present 3 months (12 weeks) or longer after the vaccination.

• 2 — The lump is larger than 2 cm in diameter (roughly the size of a grape or about an inch).

• 1 — The lump is increasing in size 1 month (4 weeks) after the injection.

What is the most common adverse reaction to feline vaccines?

localized inflammation, mild lethargy, and fever

What is the main purpose of the “3-2-1” rule in veterinary practice?

to identify potential injection site sacromas that may require further examination

For kittens, the core vaccination series typically begins at

6-8 weeks of age

According to the AAHA/AAFP Feline Vaccination Guidelines, the Feline Leukemia Virus (FeLV) vaccine is considered

a core vaccine only for kittens and young cats under 1 year of age, with further vaccination based on lifestyle risk assessment

What are the core-vaccines for cats?

FVRCP (Combination Vaccine) [includes Feline Calicivrius (FCV), Feline Herpesvirus-1 (FHV-1), and Feline Panleukopenia Virus (FPV)], Rabies, and FeLV

What are the core vaccines for dogs?

Canine Parvovirus (CPV), Canine Distemper Virus (CDV), Canine Adenovirus Type 1 & 2 (CAV-1 / CAV-2), Rabies, and Leptospirosis

After the intial core vaccine series for kittens, a booster is recommended at

6 months of age

What are the ready-made antigen vaccines?

killed, subunit, VLP and toxoid

What are the vaccines with antigen made in the host?

modified-live, vector, DNA or RNA

T/F. Antigen expression does not always mean productive replication.

true

_____ develops memory; _____ gives temporary protection

__active immunity___ develops memory; __passive antibody___ gives temporary protection

External antigen favors ____ and _____

External antigen favors _MHC 2___ and __CD4 T-cell help___

Antigen produced inside cells favors ______ and _____

Antigen produced inside cells favors _MHC 1__ and __CD8 T cells___

What do adjuvants do?

they may activate innate immunity with danger signals, improve antigen delivery, prolong antigen clearance, activate APC signals improving adaptive responses

_____ protects the young animal but may block vaccination

maternal antibody

What is the susceptibility window?

too little antibody to protect, enough to interfere

Repeated early vaccine doses create opportunities for

successful priming

A true booster recalls a response that

already developed

What are the core dog vaccines?

canine distemper, infectious canine hepatitis (adenovirus), canine paroviral enterisitis, laptospirosis, rabies

What should a booster be given for canine distemper, infectious canine hepatitis (adenovirus), and canine parvoviral enteritis?

booster within 1 year after the puppy series, then every 3 years

What should a booster be given for leptospirosis?

two inital doses, 2-4 weeks apart, booster within 1 year, then annually

What should a booster be given for rabies?

first booster 1 year after the initial dose; then every 1 or 3 years, according to label and law

When should puppy distemper-adenovirus-parovirus series be given?

every 2-4 weeks through at least 16 weeks

What are the core cat vaccines?

feline viral rhinotracheitis (herpesvirus), feline calcivirus disease, feline panleukopenia, feline leukemia, rabies

feline leukemia is core for cats…

younger than 1 year

What is the booster timing for feline viral rhinotracheitis (herpesvirus), feline calcivirus disease, and feline panleukopenia?

revaccinate at 6 months of age after the kitten series; then generally every 3 yaers for injectable products

What is the booster timing for feline leukemia?

two initial doses, 3-4 weeks apart; booster 12 months after the series. continue according to exposure risk and product