If you strip a virus of its virulence factors, it becomes weak and harmless (______).
Many vaccines use a live, but weakened (______) version of the virus.
attenuated
attenuated
The ______ is that "I think I'm coming down with something" phase. It's the early feeling you get (fever, body aches, chills) right before the actual, specific sickness—like a distinct rash or a massive sore throat—shows its face.
Why it happens: These aren't actually caused by the virus damaging your cells yet; they are caused by your immune system releasing alarms (______) as it realizes it's under attack.
prodrome
cytokines
Convalescence is just a fancy medical word for the _____ _____. It's the period when your body has officially won the battle against the virus, but it's still cleaning up the mess and repairing the damage.
recovery phase
______ is probably the most common route of viral infection.
Inhalation
The transport of virus in the blood is termed _____.
viremia
1. The First Wave (Primary Viremia): The virus enters the bloodstream in _____ numbers and hitches a ride to local "staging areas" like the liver, lungs, or immune cells .
small
2. The ______ : The virus uses these organs like breeding factories. It replicates rapidly inside them, pumping out millions of new copies of itself.
Amplification
3. The Second Wave (Secondary Viremia): Once these factory organs are overflowing, they dump a massive ______ wave of viruses back into the ______.
second
bloodstream
4. The Final Strike (Target Tissue): This overwhelming second wave delivers the virus to its ultimate destination (the ____ tissue), which determines the actual disease you get.
target
An encephalitis virus enters the brain. Which route did it use?
A. Sensory neurons
B. Bloodstream
C. Macrophages
D. Cerebrospinal fluid
B. Bloodstream
A viral infection spreads from the fluid surrounding the brain into brain tissue. Which route is this?
A. Peripheral nerves
B. Bloodstream
C. Macrophage migration
D. Meninges or cerebrospinal fluid
D. Meninges or cerebrospinal fluid
Infected immune cells carry a virus across the blood-brain barrier. Which cells are responsible?
A. Macrophages
B. Neutrophils
C. B cells
D. Eosinophils
A. Macrophages — Infected macrophages can migrate into the CNS and carry the virus with them.
A virus travels from the nasal cavity to the brain through the olfactory nerve. Which route did it use?
A. Cerebrospinal fluid
B. Bloodstream
C. Peripheral or sensory neurons
D. Macrophages
C. Peripheral or sensory neurons — Viruses can travel along nerves, including olfactory neurons, to reach the brain.
A virus is continuously present or produced for a long time. What type of infection is this?
A. Latent
B. Lytic
C. Recurrent
D. Chronic
D. Chronic — A chronic infection continues for a long period.
A viral genome remains inside a cell but produces little or no virus for a period of time. What type of infection is this?
A. Latent
B. Lytic
C. Acute
D. Transforming
A. Latent — The viral genome remains quiet inside the cell.
A latent virus becomes active again and causes repeated episodes of disease. What type of infection is this?
A. Chronic
B. Lytic
C. Recurrent
D. Acute
C. Recurrent — Recurrent infections occur when a latent virus reactivates.
A virus causes an infected cell to keep growing without normal limits. What type of persistent infection is this?
A. Chronic
B. Transforming
C. Recurrent
D. Latent
B. Transforming — A transforming infection can make the cell immortal.
Many DNA viruses struggle to multiply in neurons and other non-dividing cells because these cells are locked in a ______ state and don't have the active "copier ______" that the virus needs to replicate its DNA.
resting
machinery
What is a nonpermissive cell?
A. A cell that cannot support viral replication
B. A cell that immediately releases viruses
C. A cell that produces antibodies
D. A cell that supports the complete viral cycle
A. A cell that cannot support viral replication
What is a permissive cell?
A. A cell that blocks viral entry
B. A cell that destroys the viral genome
C. A cell that supports the complete viral replication cycle
D. A cell that cannot make viral proteins
C. A cell that supports the complete viral replication cycle — It provides the machinery needed to make new viruses.
What happens during a lytic viral infection?
Viral _____ kills the infected cell
replication
The microscope reveals giant, multi-headed cells containing dozens of nuclei crowded together. Which viral mechanism directly caused the formation of these large, multi-nucleated cells?
A. The virus used host DNA polymerase to copy its genome inside the nucleus.
B. Viral surface fusion proteins forced the membranes of adjacent host cells to melt together.
C. The virus released toxic enzymes that dissolved the extracellular matrix between the skin cells.
D. The virus blocked cellular mitosis, causing a single cell to grow massive without dividing.
B. Viral surface fusion proteins forced the membranes of adjacent host cells to melt together.
How do syncytia help a virus spread?
A. They allow direct cell-to-cell spread
B. They increase antibody production
C. They prevent viral attachment
D. They destroy viral proteins
A. They allow direct cell-to-cell spread — The virus can move between fused cells without entering the extracellular space.
Why can spreading through syncytia help a virus avoid antibodies?
A. Antibodies cannot enter the blood
B. The virus stops making proteins
C. The virus does not need to leave the cells
D. Antibodies become viral receptors
C. The virus does not need to leave the cells
A virus causes visible changes in the shape or appearance of an infected cell. What are these changes called?
A. Selection pressure
B. Cytopathologic effects
C. Complementation
D. Reassortment
B. Cytopathologic effects
A stained infected cell contains a new visible structure made of viral or altered cellular material. What is this structure called?
A. Syncytium
B. Plaque
C. Virion
D. Inclusion body
D. Inclusion body — Inclusion bodies can be seen inside infected cells.
Why are viral inclusion bodies useful?
A. They can help with laboratory diagnosis
B. They prevent viral replication
C. They produce antibodies
D. They repair damaged cells
A. They can help with laboratory diagnosis
What happens to the host cell during a persistent infection?
A. It always immediately lyses
B. It becomes a bacterial cell
C. It remains alive while the infection continues
D. It loses its entire genome
C. It remains alive while the infection continues
A DNA virus enters a cell that cannot transcribe all of its viral genes. What may result?
A. Immediate lysis
B. Latent infection
C. Antigenic shift
D. Reassortment
B. Latent infection
Some viruses suppress their own replication to remain in the host longer. What does this promote?
A. Acute bacterial infection
B. Immediate cell death
C. Viral clearance
D. Latency
D. Latency — Reduced viral replication allows long-term persistence.
Which feature is typical of a transformed cell?
A. Continued growth without normal aging
B. Immediate destruction after division
C. Inability to use glucose
D. Complete loss of protein synthesis
A. Continued growth without normal aging
Viral transformation can change which properties of a cell?
A. Only its DNA sequence
B. Only its membrane thickness
C. Its shape and metabolism
D. Only its number of chromosomes
C. Its shape and metabolism
Which change may occur in a transformed cell?
_____ growth and increased _____ uptake
Faster growth and increased sugar uptake
Normal cells usually stop growing when they touch nearby cells. What may transformed cells lose?
A. Viral receptors
B. Their nucleus
C. Their cell membrane
D. Contact inhibition
D. Contact inhibition — Transformed cells may continue growing even when crowded.
What may transformed cells do when grown in laboratory culture?
A. Grow in suspension or pile up into foci
B. Stop dividing after touching another cell
C. Immediately undergo apoptosis
D. Produce bacterial spores
A. Grow in suspension or pile up into foci — These are signs of abnormal growth.
How can a virus help immortalize a cell?
A. By blocking all protein production
B. By destroying growth genes
C. By activating growth-stimulating genes
D. By stopping glucose transport
C. By activating growth-stimulating genes — These genes push the cell to keep dividing.
Viruses can promote uncontrolled cell growth by removing what?
A. Viral attachment proteins
B. Normal brakes on DNA synthesis and cell growth
C. Host-cell ribosomes
D. Cell-surface sugars
B. Normal brakes on DNA synthesis and cell growth
How does preventing apoptosis help a virus transform a cell?
A. It stops viral entry
B. It destroys viral DNA
C. It prevents cell division
D. It keeps the infected cell alive
D. It keeps the infected cell alive
Some viruses promote cell growth by producing or inducing what?
A. Growth-stimulating cytokines
B. Antiviral antibodies
C. Complement proteins
D. Bacterial toxins
A. Growth-stimulating cytokines
DNA viruses commonly immortalize what type of cell?
A. Fully permissive cell
B. Nonpermissive cell
C. Semipermissive cell
D. Red blood cell
C. Semipermissive cell
What occurs in a semipermissive cell infected by an oncogenic DNA virus?
Selected viral _____ are expressed, but new _____ are not produced
Selected viral genes are expressed, but new viruses are not produced
HPV and SV40 promote cell transformation by interfering with which tumor-suppressor protein?
_____
p53
What type of virus is human T-cell lymphotropic virus 1?
A. Oncogenic retrovirus
B. Nonenveloped DNA virus
C. Segmented RNA virus
D. Bacteriophage
A. Oncogenic retrovirus
HTLV-1–associated leukemia usually develops over what time period?
A. Several hours
B. Several days
C. About 20–30 years
D. Less than one month
C. About 20–30 years
Which early immune signals commonly produce flu-like symptoms during a viral infection?
A. Antibodies and complement
B. Histamine and IgE
C. Hemoglobin and albumin
D. Interferons and cytokines
D. Interferons and cytokines — These signals can cause fever, fatigue, and body aches.
Antibodies are most effective against viruses in which location?
A. Outside infected cells
B. Inside the nucleus
C. Inside the cytoplasm
D. Integrated into host DNA
A. Outside infected cells — Antibodies neutralize extracellular virus particles.
Why may antibodies be enough to control some cytolytic viruses?
A. Antibodies directly kill all infected cells
B. Cytolytic viruses cannot make proteins
C. Viral replication kills the infected cell that produces the virus
D. Cytolytic viruses never enter cells
C. Viral replication kills the infected cell that produces the virus.
Which immune response is needed to destroy cells infected with a noncytolytic virus?
A. Antibody production
B. Cell-mediated immunity
C. Complement production
D. IgE-mediated immunity
B. Cell-mediated immunity
Which immune response is especially important for enveloped viruses, such as hepatitis A?
A. Antibody neutralization
B. Mucus production
C. Stomach acid
D. Cell-mediated immunity
D. Cell-mediated immunity
Which immune response is best at limiting the local spread of a virus between infected cells?
A. Serum antibody
B. Cell-mediated immunity
C. Complement alone
D. IgE production
B. Cell-mediated immunity
What can serum antibodies prevent during a viral infection?
A. Viremic spread to the target tissue
B. Viral replication inside the nucleus
C. T-cell production
D. Formation of infected cells
A. Viremic spread to the target tissue
The symptoms of measles, mumps, and viral hepatitis are caused mainly by what?
A. Viral toxins
B. Direct bacterial invasion
C. T-cell–induced inflammation
D. Antibody deficiency
C. T-cell–induced inflammation — Much of the tissue damage comes from the immune response rather than direct viral destruction.
Large amounts of viral antigen and antibody are present in the blood during chronic hepatitis B infection. What reaction can occur?
A. Type I hypersensitivity
B. Type II hypersensitivity
C. Type IV hypersensitivity
D. Type III immune complex hypersensitivity
D. Type III immune complex hypersensitivity
Why may young children have milder symptoms from viruses such as measles, mumps, EBV, and varicella-zoster virus?
A. Their T-cell inflammatory response may be less intense
B. They cannot become infected
C. Their viruses cannot replicate
D. They produce no antibodies
A. Their T-cell inflammatory response may be less intense — A weaker inflammatory response may cause fewer symptoms.
What happens during the incubation period of a viral infection?
A. The virus has been completely cleared
B. The virus is replicating, but symptoms have not started
C. Antibodies have destroyed all infected cells
D. The virus has stopped multiplying
B. The virus is replicating, but symptoms have not started — It has not yet reached the target tissue or caused enough damage.
Why can nonenveloped viruses survive longer outside the body?
A. They have an extra lipid membrane
B. They reproduce on objects
C. Their capsids resist drying and harsh conditions
D. They contain host-cell enzymes
C. Their capsids resist drying and harsh conditions — Naked capsids can tolerate detergents, changes in pH, and temperature better than envelopes.
What is a fomite?
A. A contaminated object that can transmit infection
B. An infected insect
C. A viral surface protein
D. An immune complex
A. A contaminated object that can transmit infection — Examples include contaminated doorknobs, toys, and medical equipment.
Which route commonly spreads nonenveloped viruses?
A. Organ transplantation
B. Fecal-oral transmission
C. Blood transfusion
D. Sexual contact
B. Fecal-oral transmission — Their durable capsids allow them to survive the environment and gastrointestinal tract.
A person becomes infected after touching a contaminated object and then touching their mouth. What transmitted the virus?
A. A vector
B. A droplet nucleus
C. A fomite
D. A transplant
C. A fomite — A fomite is an object that carries an infectious organism.
Which group of routes commonly spreads nonenveloped viruses?
A. Respiratory, fecal-oral, and contaminated objects
B. Injection, transplantation, and blood
A. Respiratory, fecal-oral, and contaminated objects
Why do enveloped viruses usually require closer contact for transmission?
Their _____ envelopes are easily damaged outside the body
lipid
Which route can transmit an enveloped virus while protecting its fragile envelope?
A. Dry contaminated surfaces
B. Extreme stomach acid
C. Body fluids
D. Prolonged drying
C. Body fluids
Which routes may spread enveloped viruses directly into the body?
A. Injection and organ transplantation
B. Dry surfaces and soil
C. Fecal-oral transmission
D. Food left at room temperature
A. Injection and organ transplantation
A viral disease that passes between animals and humans is called what?
A. Viremia
B. Latency
C. Zoonosis
D. Fomite
C. Zoonosis
Which viral problem becomes more common as the immune system weakens with age?
A. Formation of bacterial spores
B. Reactivation of latent viruses
C. Loss of viral receptors
D. Elimination of all viral infections
B. Reactivation of latent viruses — Previously silent viruses may reactivate in older adults.
An older patient's specific immune profile renders him uniquely susceptible to which of the following clinical scenarios compared to a younger adult?
A. Severe clinical presentation of primary viral infections due to an expanded reservoir of naive T-cells.
B. Elevated risk of both novel viral pathogens and reactivation of latent viral reservoirs due to immunosenescence.
C. Exclusive susceptibility to non-enveloped viral pathogens requiring cell-mediated clearance.
D. Rapid clearance of newly encountered viral respiratory pathogens via intact mucosal innate defenses.
B. Elevated risk of both novel viral pathogens and reactivation of latent viral reservoirs due to immunosenescence.
A patient with severe vitamin deficiency develops a more dangerous case of measles. Which vitamin is most likely deficient?
Vitamin A
_____ infection is a persistent infection with limited viral macromolecular synthesis but no virus synthesis.
latent
_____ infection consists of periods of latency followed by virus production.
Recurrent
Phosphorylation of ______ inhibits viral protein synthesis by preventing ribosome assembly on 5′-capped mRNA.
A. eEF-2
B. eIF-4E
C. eIF-2a
D. Cap-binding complex
C. eIF-2a
_____ and some other viruses prevent the above process by inhibiting
PKR or activating a phosphatase that dephosphorylates eIF-2α.
Herpesviruses
An infected host cell places viral proteins (antigens) onto its outer cell membrane. What is the direct consequence of displaying these viral pieces?
A. The cell is targeted for immune cytolysis
B. The cell becomes completely hidden from antibodies
C. The cell stops making all viral proteins
D. The virus is forced to become latent
A. The cell is targeted for immune cytolysis
A virus replicates so aggressively inside a host cell that it physically ruptures the cell’s lysosomes, spilling digestive acids. What is the immediate result of this structural disruption?
A. The virus is safely trapped inside the cell forever
B. The cell dies from internal self-digestion
C. The immune system repairs the cell membrane
D. The cell transforms into a immortal cancer cell
B. The cell dies from internal self-digestion
HSV establishes latent infection in _____ that lack the nuclear factors required to transcribe immediate early viral genes
neurons
HPV, SV40, and adenovirus encode proteins that inactivate p53 and ____, releasing cell-cycle control.
Rb
EBV immortalizes ____ cells by stimulating cell growth and preventing apoptosis.
B
Some _____ cause oncogenesis by encoding viral oncogenes that stimulate cell growth.
retroviruses
While there are plenty of retroviruses out there (like HIV), HTLV-1 is the only one that directly transforms _____ cells into cancer
human
How does HTLV-1 promote cancer formation?
A. It carries a viral oncogene
B. It produces the TAX protein
C. It destroys all T cells
D. It blocks viral integration
B. It produces the TAX protein
Which growth-promoting cytokine gene is activated by the HTLV-1 TAX protein?
A. IL-4
B. IL-10
C. IL-2
D. IFN-γ
C. IL-2
How can HTLV-1 integration contribute to cancer?
A. It can activate nearby cellular growth genes
B. It removes all host chromosomes
C. It prevents the cell from dividing
D. It destroys nearby viral genes
A. It can activate nearby cellular growth genes — Viral integration can turn on genes that stimulate cell growth.
How do hepatitis B and hepatitis C viruses mainly promote liver cancer?
A. By directly carrying cancer genes
B. By producing growth hormones
C. Through chronic inflammation and repeated liver cell regeneration
D. By preventing all liver cell division
C. Through chronic inflammation and repeated liver cell regeneration — Continuous damage and repair increase the chance of mutations.
Why does repeated liver cell regeneration increase the risk of cancer in chronic HBV or HCV infection?
A. More cell division increases the chance of mutations
B. It prevents viral replication
C. It removes all damaged DNA
D. It stops inflammation
A. More cell division increases the chance of mutations — Repeated DNA copying makes harmful mutations more likely.
Human herpesvirus 8 is most strongly associated with which cancer?
A. Liver cancer
B. Kaposi sarcoma
C. Cervical cancer
D. Adult T-cell leukemia
B. Kaposi sarcoma — HHV-8 is the major viral cause of Kaposi sarcoma.
How does HHV-8 promote the development of Kaposi sarcoma?
A. It encodes growth-promoting cytokines
B. It blocks all cytokine production
C. It destroys blood vessel
D. It prevents infected cells from growing
A. It encodes growth-promoting cytokines — These signals stimulate the growth and survival of infected cells.
What mainly produces the first innate immune response against a viral infection?
A. Complement and neutrophils
B. Antibodies and plasma cells
C. Interferons and cytokines
D. Eosinophils and IgE
C. Interferons and cytokines — These provide the early antiviral response before antigen-specific immunity develops.
Why does the antigen-specific immune response not control a new viral infection immediately?
A. It takes several days to become activated
B. It cannot recognize viruses
C. It works only against bacteria
D. It begins only after the virus is gone
A. It takes several days to become activated — Specific T cells and antibodies must first be activated and expanded.
How does antigen-specific immunity help resolve a viral infection?
A. By increasing viral attachment
B. By eliminating free viruses and infected cells
C. By preventing cytokine production
D. By producing bacterial toxins
B. By eliminating free viruses and infected cells — Antibodies target extracellular virus, while T cells target infected cells.
How do CMV and adenovirus help infected cells escape T-cell killing?
A. They increase MHC I expression
B. They block all cytokines
C. They remove viral receptors
D. They inhibit MHC I expression
D. They inhibit MHC I expression — Reduced MHC I makes viral antigens harder for cytotoxic T cells to detect.
Which influenza changes help the virus avoid previously formed antibodies?
A. Antigenic drift and antigenic shift
B. Complementation and marker rescue
C. Transcapsidation and latency
D. Lysis and transformation
A. Antigenic drift and antigenic shift — These changes alter influenza surface antigens.
What process helps HIV escape antibody recognition over time?
A. Antigenic variation
B. Reassortment
C. Capsid removal
D. Plaque formation
A. Antigenic variation — Frequent mutations change HIV antigens and reduce antibody effectiveness.
What causes many of the fever, fatigue, and body aches associated with viral infections?
A. Viral capsids
B. Interferons and cytokines
C. Red blood cell destruction
D. Antibody deficiency
B. Interferons and cytokines — These immune signals produce many flu-like systemic symptoms.
What is a cytokine storm?
A. A failure to produce cytokines
B. A normal antibody response
C. Excessive and uncontrolled cytokine production
D. The removal of all infected cells
C. Excessive and uncontrolled cytokine production — Too many cytokines can cause widespread inflammation and organ damage.
In a genetically predisposed person, severe immune dysregulation after a viral infection may contribute to what?
A. Autoimmune disease
B. Bacterial sporulation
C. Loss of all antibodies
D. Viral reassortment
A. Autoimmune disease — An abnormal immune response may begin attacking the person’s own tissues.
Why can the immune response to an enveloped virus damage tissue?
A. T cells may attack infected host cells
B. Antibodies prevent all inflammation
C. Enveloped viruses cannot enter cells
D. Complement repairs infected tissue
A. T cells may attack infected host cells — Cell-mediated immunity can cause immunopathology while removing infected cells.
In dengue hemorrhagic fever, enhanced immune responses can damage which cells?
A. Red blood cells
B. Endothelial cells
C. Neurons
D. Bone cells
B. Endothelial cells — Excessive T-cell and antibody responses can damage blood vessel lining.
In atypical measles, an enhanced immune response can cause inflammation in which tissues?
A. Liver and kidneys
B. Brain and heart
C. Skin and lungs
D. Bone and muscle
C. Skin and lungs — Strong antigen-specific responses can produce inflammatory tissue damage.
Why are asymptomatic viral infections important to public health?
A. They never spread
B. They are major sources of contagion
C. They always become latent
D. They affect only animals
B. They are major sources of contagion — People can transmit the virus without realizing they are infected.
Why are sexually transmitted viral infections often spread unknowingly?
A. Transmission can occur during asymptomatic infection
B. Sexual transmission always causes immediate symptoms
C. The viruses cannot be detected in fluids
D. Antibodies increase viral spread
A. Transmission can occur during asymptomatic infection — A person may feel healthy while still being contagious.
What is typical of prion diseases and some slowly progressive viral infections?
A. Very short incubation periods
B. Immediate severe symptoms
C. Long incubation periods
D. Complete recovery within hours
C. Long incubation periods — Damage may build up for years before symptoms become obvious.
Why may symptoms progress quickly after the long incubation period of a prion disease?
A. Enough tissue damage has accumulated
B. The prion suddenly becomes a bacterium
C. Antibodies begin producing viruses
D. The nervous system starts making viral envelopes
A. Enough tissue damage has accumulated — Clinical decline may appear rapid once damage reaches a critical level.
Why are health care workers at increased risk for certain viral infections?
A. They are exposed to contaminated blood and body fluids
B. They cannot produce antibodies
C. They are exposed only to airborne bacteria
D. Viruses replicate on their skin
A. They are exposed to contaminated blood and body fluids — Needlesticks and contact with infectious fluids can transmit viruses.
Which viruses can be transmitted through contaminated blood?
A. HSV and influenza
B. HBV and HIV
C. Measles and mumps
D. Rhinovirus and rotavirus
B. HBV and HIV — Both can spread through exposure to infected blood.
Which virus may be transmitted through contact with fluid from a skin vesicle?
A. Hepatitis A virus
B. Influenza virus
C. Herpes simplex virus
D. Adenovirus
C. Herpes simplex virus — HSV is present in fluid from active vesicular lesions.
How are viruses that replicate in the respiratory tract commonly transmitted?
A. Fecal-oral transmission
B. Aerosol or respiratory droplets
C. Insect bites only
D. Organ transplantation only
B. Aerosol or respiratory droplets — Coughing, sneezing, and breathing can spread respiratory viruses.
How are enteric viruses commonly transmitted?
A. Fecal-oral route
B. Blood transfusion
C. Respiratory droplets
D. Vesicle fluid
A. Fecal-oral route — These viruses are shed in stool and enter through the mouth.
Why can cytomegalovirus be found in many different body secretions?
A. It infects mucoepithelial and secretory cells throughout the body
B. It infects only red blood cells
C. It cannot enter epithelial cells
D. It replicates only in the lungs
A. It infects mucoepithelial and secretory cells throughout the body
Why must enveloped viruses usually remain wet during transmission?
A. Their genomes dissolve when dry
B. Their lipid envelopes are easily damaged by drying
C. Water causes viral replication
D. Their capsids are made entirely of fluid
B. Their lipid envelopes are easily damaged by drying — Loss of the intact envelope usually makes the virus noninfectious.
What is the role of an animal or insect vector?
A. It maintains a virus only within one host
B. It carries a virus to a new host
C. It produces antiviral antibodies
D. It destroys the viral genome
B. It carries a virus to a new host — Vectors transmit viruses between hosts.
What is the role of an animal reservoir?
A. It maintains and amplifies a virus in nature
B. It immediately eliminates the virus
C. It prevents the virus from reaching humans
D. It carries only bacterial infections
A. It maintains and amplifies a virus in nature — Reservoir hosts help the virus continue circulating.
What is an arbovirus?
A. A virus transmitted by arthropods
B. A virus transmitted through blood
C. A virus that infects plants
D. A virus with no genetic material
A. A virus transmitted by arthropods — Mosquitoes and ticks are common arthropod vectors.
Why are older adults more susceptible to new influenza strains?
A. Their virus-specific immune responses decline with age
B. They produce too many new lymphocytes
C. Influenza cannot infect young people
D. Aging increases MHC I expression
A. Their virus-specific immune responses decline with age
Why are older adults more likely to develop shingles?
A. They are newly infected with varicella every year
B. Varicella-zoster immunity declines with age
C. The virus is transmitted only in old age
D. Antibodies cause the virus to enter neurons
B. Varicella-zoster immunity declines with age — Reduced cell-mediated immunity allows latent virus to reactivate.
When are many respiratory viral infections most common?
A. Winter
B. Summer
C. Only spring
D. Only autumn
A. Winter
Some enteric viruses, especially enteroviruses, are more common during which season?
A. Winter
B. Autumn
C. Summer
D. Early spring
C. Summer
Which intestinal cells can transport enteric viruses to the lymphatic system?
A. Goblet cells
B. M cells
C. Red blood cells
D. Neurons
B. M cells — M cells carry viruses across the intestinal lining to underlying lymphatic tissue.
Where do M cells deliver enteric viruses after carrying them across the intestinal lining?
A. Peyer patches
B. Bone marrow
C. Thymus
D. Spleen
A. Peyer patches
Which viruses commonly use M cells to reach Peyer patches?
A. Herpesviruses and poxviruses
B. Retroviruses and adenoviruses
C. Picornaviruses and reoviruses
D. Hepatitis B and hepatitis C viruses
C. Picornaviruses and reoviruses
What are the two main systems that spread viruses through the body?
A. Digestive and skeletal systems
B. Bloodstream and lymphatic system
C. Endocrine and urinary systems
D. Muscular and nervous systems
B. Bloodstream and lymphatic system
Where do many viruses begin an infection?
A. Oral mucosa or upper respiratory tract
B. Bone marrow or joints
C. Heart or kidneys
D. Brain or spinal cord
A. Oral mucosa or upper respiratory tract
How can a virus enter the body through the skin?
A. Through an intact outer skin layer
B. Through breaks in the skin
C. Through hair
D. Through sweat production
B. Through breaks in the skin
Viruses can enter through mucoepithelial membranes located where?
A. Around body openings
B. Only inside bones
C. Only in the brain
D. Inside skeletal muscles
A. Around body openings
What is the purpose of viral virulence factors?
A. To help the host eliminate the virus
B. To stop all viral gene expression
C. To help the virus infect, spread, and survive
D. To prevent the virus from binding cells
C. To help the virus infect, spread, and survive — Virulence factors promote disease within the host.
Which viral activity may be promoted by a virulence factor?
A. Replication and transmission
B. Antibody class switching
C. Red blood cell production
D. Bone formation
A. Replication and transmission — Virulence factors can help a virus multiply and move to new hosts.
How can viral virulence factors help a virus reach its target tissue?
A. By blocking all movement through the body
B. By promoting access and attachment to target cells
C. By destroying the viral genome
D. By preventing receptor binding
B. By promoting access and attachment to target cells — The virus must reach and bind the cells it can infect.
How can viral virulence factors help a virus remain in the host?
A. By helping it escape host defenses
B. By stopping its own replication permanently
C. By increasing antibody recognition
D. By preventing entry into cells
A. By helping it escape host defenses — Immune evasion allows the virus to survive longer.
Why may some viral virulence factors be unnecessary in tissue culture but important inside a person?
A. Tissue culture contains no living cells
B. Viruses face fewer barriers and immune defenses in tissue culture
C. Viruses cannot replicate in tissue culture
D. Tissue culture always produces antibodies
B. Viruses face fewer barriers and immune defenses in tissue culture — Inside a host, the virus must spread and avoid immune clearance.
What does tissue tropism mean?
A. A virus’s preference for a particular tissue or cell type
B. A virus’s ability to survive on objects
C. The movement of viruses through blood
D. The destruction of all infected cells
A. A virus’s preference for a particular tissue or cell type — Viruses infect tissues that contain the proper receptors and machinery.
How can different viruses cause the same type of disease?
A. They may all target the same tissue
B. They must have identical genomes
C. They always use the same receptor
D. They must belong to the same virus family
A. They may all target the same tissue — Similar tissue tropism can produce similar symptoms.
Which viral diseases are especially common in infants and young children?
A. Respiratory infections and viral rashes
B. Only chronic hepatitis
C. Only neurologic infections
D. Only latent infections
A. Respiratory infections and viral rashes — Young children commonly develop respiratory and exanthematous viral illnesses.