Question 1

Which of the following best describes the difference between positive-sense single-stranded RNA (+ssRNA) viruses and negative-sense single-stranded RNA (-ssRNA) viruses?

Accepted Answer

+ssRNA viruses can be directly used as mRNA by host ribosomes, while -ssRNA viruses must first be transcribed into mRNA.

Question 2

A patient presents with acute gastroenteritis characterized by diarrhea but no vomiting. Which virus is most likely responsible for these symptoms?

Accepted Answer

Astrovirus

Question 3

Which of the following is the most effective method for preventing the transmission of rhinoviruses, the most common cause of the common cold?

Accepted Answer

Handwashing

Question 4

A child develops a fever, sore throat, and vesicular lesions on the hands, feet, and inside the mouth. Which virus is most likely responsible for these symptoms?

Accepted Answer

Coxsackie A virus

Question 5

Which of the following statements about poliovirus is TRUE?

Accepted Answer

Poliovirus can cause asymptomatic, minor, nonparalytic, and paralytic infections.

Question 6

Which of the following best explains why hepatitis D virus (HDV) requires hepatitis B virus (HBV) for virulence?

Accepted Answer

HDV cannot attach to liver cells without HBV envelope proteins.

Question 7

A hospital ward in the 1950s is filled with patients in mechanical respirators (iron lungs). Which viral disease is most likely responsible for this scenario?

Accepted Answer

Poliomyelitis

Question 8

Which of the following viruses is most commonly associated with zoonotic transmission via mosquitoes and can cause encephalitis in humans?

Accepted Answer

Togavirus

Question 9

Which of the following best describes the replication strategy of retroviruses?

Accepted Answer

They use reverse transcriptase to synthesize double-stranded DNA from their RNA genome.

Question 10

A patient is diagnosed with AIDS. Which of the following criteria must be met for this diagnosis?

Accepted Answer

Presence of HIV antibodies and a CD4 count below 200 cells/μL

Question 11

Which of the following is a major challenge in developing a vaccine for HIV?

Accepted Answer

HIV glycoprotein gp120 exhibits high antigenic variability.

Question 12

Which of the following viruses is most likely to cause severe, often fatal, hemorrhagic fever with uncontrolled bleeding and a mortality rate up to 90%?

Accepted Answer

Ebola virus

Question 13

A segmented, negative-sense RNA virus causes annual outbreaks of respiratory illness with fever, malaise, and myalgia. Which process is responsible for the emergence of new viral strains that can lead to pandemics?

Accepted Answer

Antigenic shift

Question 14

Which of the following viruses is the leading cause of fatal respiratory disease in infants and young children, often resulting in dyspnea and syncytia formation in the lungs?

Accepted Answer

Respiratory syncytial virus (RSV)

Question 15

A patient presents with parotitis (painful swelling of the parotid glands) but recovers completely without specific treatment. Which virus is most likely responsible?

Accepted Answer

Mumps virus

Question 16

Which of the following viruses is most commonly associated with outbreaks of acute gastroenteritis in day care centers and hospitals, causing diarrhea, nausea, and vomiting?

Accepted Answer

Calicivirus (e.g., norovirus)

Question 17

Which of the following statements about hepatitis A virus (HAV) is TRUE?

Accepted Answer

HAV is transmitted via the fecal-oral route and does not cause chronic infection.

Question 18

Which of the following viruses is most likely to cause a zoonotic disease transmitted by ticks, resulting in fever and chills, and is usually self-limiting?

Accepted Answer

Coltivirus (Colorado tick fever)

Question 19

A patient develops severe pneumonia after inhaling dried rodent urine in the southwestern United States. Which virus is most likely responsible?

Accepted Answer

Hantavirus

Question 20

Which of the following best explains why vaccination against hepatitis B virus (HBV) also helps prevent hepatitis D virus (HDV) infection?

Accepted Answer

HDV requires HBV for attachment and virulence, so preventing HBV infection prevents HDV infection.

RNA Viruses: Structure, Classification, and Human Diseases

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