Question 1

The recent epidemic of SARS virus was caused by a(n)

Accepted Answer

The recent epidemic of SARS (Severe Acute Respiratory Syndrome) virus was caused by a coronavirus.

Question 2

Fever,jaundice,and hemorrhaging which often results in "black vomit" are characteristics of

Accepted Answer

The symptoms described are characteristic of yellow fever, a viral infection transmitted by mosquitoes. The fever, jaundice, and hemorrhaging can lead to organ failure and death, and the name "yellow fever" comes from the yellowing of the skin and eyes that occurs due to liver damage. "Black vomit" can also occur due to internal bleeding. Yellow fever is preventable with a vaccine.

Question 3

Which of the following is a family of double-stranded RNA viruses?

Accepted Answer

Reoviridae is a family of double-stranded RNA viruses, while Picornaviridae, Coronaviridae, Retroviridae, and Rhabdoviridae are families of single-stranded RNA viruses.

Question 4

Which of the following viruses can establish a chronic infection of the liver which may progress to liver cancer?

Accepted Answer

Hepatitis C virus can establish a chronic infection of the liver and over time, may cause liver damage, liver cancer, and liver failure. The other viruses listed do not typically result in chronic liver infections or do not have a strong association with liver cancer.

Question 5

Colorado tick fever is caused by a ________ and can cause headache,muscle aches and conjunctivitis in some individuals.

Accepted Answer

Colorado tick fever is caused by a virus called coltivirus. The symptoms include headache, muscle aches, and conjunctivitis. None of the other options are known to cause Colorado tick fever.

Question 6

Rodents are the normal hosts for which of the following encephalitis viruses?

Accepted Answer

Rodents are the primary hosts for Venezuelan equine encephalitis (VEE) virus, while the other viruses typically have birds as their primary hosts.

Question 7

Which of the following characteristics distinguishes coronaviruses from rhinoviruses?

Accepted Answer

Coronaviruses have an envelope surrounding the virion, while rhinoviruses do not.

Question 8

A scientist discovers a new virus affecting birds.After isolation,the virus is characterized as having single-strand RNA in an icosahedral capsid and an envelope.To which of the following virus families might this new virus belong?

Accepted Answer

The Flaviviridae family consists of enveloped viruses with single-stranded RNA and icosahedral capsids, matching the characteristics of the newly discovered virus.

Question 9

Which of the following cells are a major reservoir for and distributor of HIV?

Accepted Answer

Monocytes and macrophages are the major reservoir and distributor of HIV. They are also referred to as the "target cells" of the virus. HIV primarily infects and replicates within these cells, and they are responsible for spreading the virus throughout the body via the bloodstream and lymphatic system. Helper T cells, B lymphocytes, and cytotoxic T cells can also be infected by HIV, but they are not the major reservoirs of the virus. Infected dendritic cells can present HIV to target cells, but they are not the primary distributors of the virus.

Question 10

An emerging fatal disease in humans caused by one of the members of the Paramyxoviridae is known as

Accepted Answer

Nipah virus is a member of the Paramyxoviridae family and has emerged as a fatal disease in humans. It was first identified in Malaysia in 1998 and since then, outbreaks have occurred in Bangladesh and India. The virus is transmitted to humans from animals (particularly pigs and fruit bats) and has a high mortality rate.

Question 11

How are HIV virions rendered virulent?

Accepted Answer

HIV virions are rendered virulent after the action of protease, which releases reverse transcriptase and capsomeres after the virion buds from the cell. This allows the viral RNA to be reverse transcribed into DNA within the host cell, which can then integrate into the host genome and continue to produce new viral particles.

Question 12

Which of the following enzymes allows retroviruses to transcribe DNA from ssRNA?

Accepted Answer

Retroviruses rely on reverse transcriptase to transcribe their RNA genome into DNA, which can then be integrated into the host cell's genome. This is a key step in the viral life cycle and allows the virus to continue replicating within the host. Protease, DNA polymerase, integrase, and nuclease are all important enzymes in various biological processes, but they do not play a direct role in retroviral replication.

Question 13

Ebola hemorrhagic fever is caused by which type of virus?

Accepted Answer

Ebola hemorrhagic fever is caused by filovirus, specifically Ebola virus and Marburg virus. Rhabdovirus, paramyxovirus, rubulavirus, and pneumovirus are all different types of viruses that do not cause Ebola hemorrhagic fever.

Question 14

The human T-lymphotropic virus 1 causes

Accepted Answer

The human T-lymphotropic virus 1 (HTLV-1) is associated with the development of adult acute T-cell lymphocytic leukemia.

Question 15

Which of the following pairs is MISMATCHED?

Accepted Answer

Hantavirus infections do not typically cause paralysis. Symptoms of hantavirus include fever, muscle aches, and respiratory distress.

Question 16

Which of the following is the most correct description of the function of reverse transcriptase?

Accepted Answer

Reverse transcriptase synthesizes a complementary DNA (cDNA) strand from an RNA template. After this, the RNA strand is degraded by the enzyme ribonuclease H, and the reverse transcriptase synthesizes a new DNA strand complementary to the cDNA, resulting in a double-stranded DNA molecule.

Question 17

Public health scientists discover and become concerned about a new strain of RNA virus among farm animals,especially geese and pigs,in the Midwest.Each virion is composed of lipid,helical proteins,and multiple pieces of RNA.This new virus may be a(n)

Accepted Answer

Influenza viruses are RNA viruses that can infect animals like pigs and birds, have a segmented RNA genome, and are known for their lipid envelope and helical proteins.

Question 18

The transmission of enteric hepatitis is most effectively prevented by

Accepted Answer

Enteric hepatitis, such as hepatitis A and E, is primarily transmitted through the fecal-oral route, so good public sanitation and personal hygiene are key to preventing its spread.

Question 19

Which of the following bodily fluids is commonly a source of infection by HIV?

Accepted Answer

HIV can be transmitted through breast milk, semen, and vaginal secretions, making all these bodily fluids common sources of infection.

Question 20

Which of the following cells is NOT infected by HIV?

Accepted Answer

B lymphocytes are not infected by HIV. HIV primarily infects cells of the immune system that have CD4 receptors on their surface, such as helper T cells, microglia, macrophages, and dendritic cells. B lymphocytes do not have CD4 receptors, which makes it difficult for HIV to infect them. However, HIV can indirectly affect B lymphocytes by impairing the overall immune response, which can lead to increased susceptibility to infections and complications.

Quiz 25: Pathogenic RNA Viruses