A child has severe recurrent viral and fungal infections because thymic development failed. Which diagnosis best fits?

A. Wiskott-Aldrich syndrome

B. Hyper-IgM syndrome

C. DiGeorge syndrome

D. Canale-Smith syndrome

C. DiGeorge syndrome

In DiGeorge syndrome, absent thymic tissue most directly impairs development of which organ?

A. Thymus

B. Spleen

C. Bone marrow

D. Lymph node

A. Thymus

A patient with DiGeorge syndrome has profound cellular immune dysfunction. Which cell type is primarily affected?

A. B cells

B. Neutrophils

C. Macrophages

D. T cells

D. T cells

The life-threatening infections in DiGeorge syndrome are mainly due to loss of which immune function?

A. Antibody secretion

B. T-cell function

C. Complement activation

D. Neutrophil migration

B. T-cell function

Which sequence correctly lists the major phases of HIV infection?

A. Acute, latent, recovered

B. Acute, chronic, profound immunosuppression

C. Chronic, acute, latent

D. Prodrome, remission, recovery

B. Acute, chronic, profound immunosuppression

After HIV enters a target cell, which enzyme copies viral RNA into DNA?

A. DNA polymerase

B. RNA primase

C. Reverse transcriptase

D. RAG recombinase

C. Reverse transcriptase

Reverse transcriptase converts HIV genetic material into which product?

A. cDNA

B. mRNA

C. rRNA

D. tRNA

A. cDNA

After reverse transcription, which event allows HIV DNA to persist inside the host genome?

A. Capsid degradation

B. Ribosomal binding

C. Antibody neutralization

D. Insertion into host DNA

D. Insertion into host DNA

Once HIV DNA is inserted into host DNA and remains inactive, which effector cells fail to detect it?

A. B cells

B. NK cells

C. CTLs

D. Neutrophils

C. CTLs

A patient is born with nonfunctional CD40L. Which co-stimulatory pathway is directly defective?

A. CD28-B7

B. CD40-CD40L

C. Fas-FasL

D. IgE-Fc receptor

B. CD40-CD40L

Loss of functional CD40 or CD40L most directly prevents which immune response?

A. T-dependent antibody response

B. NK-cell cytotoxicity

C. Neutrophil oxidative burst

D. Complement membrane attack

A. T-dependent antibody response

A patient with defective CD40 signaling has impaired germinal-center function. Which two processes are compromised?

Class switching and hypermutation

Without functional CD40/CD40L signaling, antibody production is biased toward which class?

IgM

Which immunodeficiency syndrome eliminates both major adaptive lymphocyte arms?

SCID

Severe combined immunodeficiency involves dysfunction of which lymphocyte groups?

B and T cells

A patient with a congenital C3 defect has lymph nodes lacking which structure?

____ ____

Germinal centers

A C3-deficient patient lacks germinal centers. Which antibody class would B cells mainly produce?

A. IgM

Initial HIV transmission commonly begins after viral penetration through which barrier?

A. Respiratory epithelium

B. Keratinized skin

C. Gastric mucosa

D. Rectal or vaginal mucosa

D. Rectal or vaginal mucosa

After crossing mucosal surfaces, HIV initially infects which target cell population?

A. B cells

B. Neutrophils

C. T cells

D. Eosinophils

C. T cells

Once inside T cells, HIV replicates by taking over which resource?

A. Complement proteins

B. Host machinery

C. Granule enzymes

D. Antibody genes

B. Host machinery

During acute HIV infection, viral replication across the body does what?

A. Stops immediately

B. Remains localized

C. Clears completely

D. Multiplies systemically

D. Multiplies systemically

During acute HIV infection, viral levels typically peak at approximately what time?

A. 3-4 weeks

B. 2-3 days

C. 6-8 months

D. 1-2 years

A. 3-4 weeks

During the chronic phase of HIV infection, what happens to viral levels?

A. Disappear completely

B. Peak immediately

C. Decline but persist

D. Remain undetectable

C. Decline but persist

As HIV progresses toward profound immunosuppression, what ultimately explains susceptibility to fatal infections?

Loss of ____ cells

Loss of T cells

HIV-1 stores its genetic information in which nucleic acid form?

RNA

Why can killer T cells fail to detect HIV-infected cells during latency?

A. HIV destroys antibodies

B. HIV blocks all cytokines

C. HIV exits immediately

D. HIV remains hidden intracellularly

D. HIV remains hidden intracellularly

A newly infected patient asks whether HIV is detected immediately. Which feature explains delayed immune recognition?

A. Acute sterilization

B. Latent cellular buildup

C. Permanent antibody absence

D. Immediate viral clearance

B. Latent cellular buildup

During the latent period of HIV, infected cells mainly serve as what?

A. Complement reservoirs

B. Reactivatable viral reservoir

C. Neutrophil traps

D. IgE-producing cells

B. Reactivatable viral reservoir

Each HIV replication cycle introduces mutations. What is the immune consequence?

A. Easier T-cell recognition

B. Faster complement fixation

C. Reduced viral diversity

D. Harder immune recognition

D. Harder immune recognition

High mutation rates help HIV maintain which advantage?

A. Immune escape

B. Antibody deletion

C. Eosinophil recruitment

D. Mast-cell activation

A. Immune escape

Which set contains the major HIV-1 target cells?

A. B cells, eosinophils, neutrophils

B. NK cells, basophils, mast cells

C. Helper T cells, macrophages, dendritic cells

D. Platelets, fibroblasts, keratinocytes

C. Helper T cells, macrophages, dendritic cells

HIV infection of macrophages and dendritic cells is especially harmful because these cells normally perform which role?

A. Kill helminths directly

B. Produce thyroid hormone

C. Form epithelial barriers

D. Activate killer T cells

D. Activate killer T cells

One reason AIDS is deadly is that HIV can persist in which state?

A. Latent phase

B. Spore phase

C. Germinal phase

D. Vegetative phase

A. Latent phase

HIV spreads efficiently because it hijacks which system?

A. Endocrine system

B. Immune system

C. Skeletal system

D. Digestive system

B. Immune system

Untreated HIV-1 infection commonly leads to death within approximately how long?

A. 6 months

B. 2 years

C. 50 years

D. 10 years

D. 10 years

People with AIDS are treated with which medication class?

A. Antihistamines

B. Antiretrovirals

C. Glucocorticoids

D. Antifungals

B. Antiretrovirals

Some patients naturally control HIV-1 without typical progression. What are they called?

A. Elite controllers

B. Latent carriers

C. Viral amplifiers

D. Seronegative hosts

A. Elite controllers

In elite controllers, pattern-recognition receptor signaling increases secretion of which two antiviral cytokines?

IFN-alpha and IFN-beta

IFN-alpha and IFN-beta help elite controllers mainly by blocking which viral process?

A. Viral entry

B. Antibody production

C. Antigen presentation

D. Viral replication

D. Viral replication

Some elite controllers have stronger MHC I molecules. Which immune response improves?

A. Faster B-cell switching

B. Stronger IgE binding

C. Faster killer T activation

D. Increased eosinophil survival

C. Faster killer T activation

Better MHC I presentation in HIV elite controllers most directly activates which cell type?

Killer T cells

Which feature best explains why HIV is difficult to eliminate after initial infection?

A. Fixed surface antigens

B. No cellular reservoir

C. Immediate immune clearance

D. Latent reactivatable reservoir

D. Latent reactivatable reservoir

A virus infects APCs needed for cytotoxic T-cell activation. Which HIV target cell group explains this? A. Eosinophils and basophils B. Macrophages and dendritic cells C. Plasma cells and B cells D. Keratinocytes and fibroblasts

B. Macrophages and dendritic cells

A patient’s HIV mutates repeatedly as it replicates. Which outcome best follows?

A. Antigenic variation

B. Thymic regeneration

C. IgE blockade

D. Fas correction

A. Antigenic variation

Which combined features make AIDS especially deadly?

A. Low mutation, rapid clearance

B. IgE binding, mast activation

C. Latency, mutation, APC infection

D. Spore formation, toxin release

C. Latency, mutation, APC infection

Immune weakness can result from mutation of how many genes?

One gene

Compared with genetic immunodeficiencies, which category affects millions of people?

_______ immunodeficiencies

Acquired immunodeficiencies

Genetic immunodeficiencies are best described as which pattern?

A. Rare disorders

B. Universal disorders

C. Acquired disorders

D. Infectious disorders

A. Rare disorders

Which virus is most intensely studied as the cause of AIDS?

HIV-1

The abbreviation HIV-1 refers to which virus?

A. Human T-cell virus one

B. Human immunodeficiency virus one

C. Herpes immunodeficiency virus one

D. Host integration virus one

B. Human immunodeficiency virus one

During acute HIV infection, the dramatic rise in total circulating virus is called what?

Viral _____

Viral load

After acute HIV peaks, viral load decreases mainly because which cells begin working?

A. Virus-specific CTLs

B. Memory B cells

C. Follicular dendritic cells

D. Tissue mast cells

A. Virus-specific CTLs

Many viral infections fully clear after the acute phase. What is this clearance called?

_____

Sterilization

Unlike many viruses, full HIV-1 infection enters which long-term phase after acute infection?

A. Chronic phase

B. Germinal phase

C. Vegetative phase

D. Allergic phase

A. Chronic phase

During chronic HIV infection, which immune populations initially remain high?

_____ and _____ cells

CTLs and Th cells

During chronic HIV infection, Th-cell numbers slowly decrease because HIV does what?

_____ them

Kills them

In chronic HIV, CTLs eventually decline because they lose help from which cells?

_____ cells

Th cells

Late in untreated HIV, CTL decline causes which virologic change?

Viral ____ rises

Viral load rises

Profound immunosuppression in AIDS most directly predisposes to which fatal complication?

A. Seasonal allergy

B. Autoimmune arthritis

C. Opportunistic infection

D. Contact dermatitis

C. Opportunistic infection

HIV can initiate latent infection within approximately what time after exposure?

A. 24 hours

B. 3-4 weeks

C. 6 months

D. 5-10 days

D. 5-10 days

Latent HIV reservoirs may form before full activation of which system?

A. Innate immune system

B. Adaptive immune system

C. Complement system

D. Coagulation system

B. Adaptive immune system

Why does HIV latency form especially early relative to adaptive immunity?

A. Antibodies appear immediately

B. CTLs mature prenatally

C. Adaptation takes about one week

D. Neutrophils suppress latency

C. Adaptation takes about one week

HIV reverse transcriptase is especially dangerous because it is highly what?

____-prone

Error-prone

The error-prone nature of HIV reverse transcriptase produces which viral consequence?

High _____ rate

D. High mutation rate

HIV escape mutants can arise after approximately how long?

A. 3-4 weeks

B. 10 days

C. 2 years

D. 10 years

B. 10 days

Once HIV escape mutants arise, original CTLs usually fail to do what?

A. Produce antibody

B. Enter lymph nodes

C. Recognize them

D. Bind complement

C. Recognize them

Which molecule functions as HIV-1’s docking protein? _____

CD4

By infecting macrophages and dendritic cells, HIV damages cells needed for which process?

A. IgE crosslinking

B. CTL activation

C. Keratinocyte growth

D. Fas signaling

B. CTL activation

HIV-infected immune cells can carry virus from tissues to which site?

A. Bone marrow

B. Thymic cortex

C. Splenic red pulp

D. Lymph nodes

D. Lymph nodes

Within lymph nodes, HIV can undergo which change?

Faster ________

Faster proliferation

In lymph nodes, HIV may be coated by antibodies or which other system?

A. Coagulation

B. Kallikrein

C. Complement

D. Fibrinolysis

C. Complement

Opsonized HIV in lymph nodes can become trapped on which stromal immune cell?

A. Macrophages

B. Follicular dendritic cells

C. Mast cells

D. Neutrophils

B. Follicular dendritic cells

ART improves survival but does not do what?

A. Eliminate HIV

B. Block replication

C. Target viral enzymes

D. Slow progression

A. Eliminate HIV

ART works mainly by targeting components of which process?

A. Antibody class switching

B. Complement activation

C. Viral replication cycle

D. T-cell thymic selection

C. Viral replication cycle

The main clinical benefit of ART is best described how?

A. Sterilizes latent reservoirs

B. Lengthens patient survival

C. Restores thymus completely

D. Prevents all cancers

B. Lengthens patient survival

Patients on ART have increased risk of cancer and which neurologic complication?

_____ disorders

Cognitive disorders

_____-term ART-treated HIV patients have increased risk affecting kidneys, liver, bone, and the heart.

long

Average lifespan on ART is approximately how much shorter than uninfected individuals?

A. 5 years

B. 10 years

C. 15 years

D. 20 years

D. 20 years

Approximately what fraction of HIV-infected individuals are elite controllers?

A. 3%

B. 0.3%

C. 10%

D. 30%

B. 0.3%

Some elite controllers can control HIV infection for as long as what duration?

A. 30 years

B. 10 days

C. 3-4 weeks

D. 5-10 days

A. 30 years

In some elite controllers, CTLs are described as unusually what?

A. Suppressed

B. Vicious

C. Latent

D. Opsonized

B. Vicious