Question 1

Viral spikes are inserted into the host cell membrane before budding or exocytosis.

Accepted Answer

Viral spikes are integral components of the viral envelope that are inserted into the membrane of the host cell during the budding process. This allows the newly formed virus particles to bind to and infect other cells.

Question 2

Viruses are unable to multiply outside of a host cell.

Accepted Answer

Viruses are obligate intracellular parasites, meaning they need a host cell in order to replicate and multiply. They lack the necessary cellular machinery to carry out metabolic processes on their own, and therefore rely entirely on the host cell's machinery to reproduce.

Question 3

Viruses contain the necessary tools to invade and control a host cell. These tools may consist of a ________.

Accepted Answer

Viruses contain a capsid or envelope which protects the nucleic acid strands of DNA or RNA. They may also have enzymes that aid in their invasion and control of the host cell. The nucleus is not typically found within a virus.

Question 4

Viruses are not filterable.

Accepted Answer

Viruses are filterable, meaning they can pass through filters that trap bacteria. This ability was first demonstrated by the scientist Dmitri Ivanovsky in 1892.

Question 5

Which of the following is not true regarding the structure and function of viral spikes?

Accepted Answer

Viral spikes are not coded for by the host genome, but are instead coded for by the viral genome.

Question 6

An ideal antiviral drug would be one that killed the host cell, effectively preventing the virus from replicating.

Accepted Answer

An ideal antiviral drug would specifically target the virus and prevent it from replicating without harming the host cell. Killing the host cell would cause damage to healthy tissue and potentially harm the patient.

Question 7

Viruses mutate and some have not been discovered.

Accepted Answer

Viruses can mutate quickly and there are likely many viruses that have not yet been discovered.

Question 8

The adeno-associated virus (AAV) is a prion.

Accepted Answer

AAV is not a prion. Prions are infectious agents composed solely of protein, while AAV is a non-pathogenic virus that requires a helper virus (such as adenovirus) to replicate.

Question 9

Respiratory syncytial virus (RSV) is a common respiratory virus that causes mild cold-like symptoms in most individuals, but can be more serious in infants and the elderly. RSV is so-named because ________.

Accepted Answer

RSV causes the fusion of damaged host cells, forming a large, multinucleated cell called a syncytium.

Question 10

A specific animal virus has the ability to attach to and enter almost any animal host cell.

Accepted Answer

Each virus has a specific host range and can only infect specific types of cells. A virus cannot attach to and enter any animal host cell.

Question 11

It is necessary to culture viruses both in vivo and in vitro so that vaccines can be developed, analysis of viral genomes can be made and viruses in clinical specimens can be identified.

Accepted Answer

Culturing viruses in both in vivo (living animals) and in vitro (laboratory cell cultures) environments allows for experimentation and study of viral behavior, which is necessary for developing vaccines, analyzing viral genomes, and identifying viruses in clinical specimens.

Question 12

Viruses are the most common cause of acute infections that do not result in hospitalization.

Accepted Answer

Viruses are the most common cause of acute infections that do not result in hospitalization, such as the common cold, flu, and many cases of sore throat and ear infections.

Question 13

The patient asks the RN how she contracted this viral infection since she has not come in contact with anyone with anyone infected with shingles. Which of the following statements is an appropriate response?

Accepted Answer

Varicella zoster virus can hide from the immune system within nerve cells, specifically in the dorsal root ganglia. When the virus reactivates, it travels down the nerve fibers and manifests as shingles. The virus can remain dormant in nerve cells for years before reactivating.

Question 14

Viruses are simple, noncellular, and lack ribosomes.

Accepted Answer

Viruses are not considered living organisms and do not have the necessary cellular machinery such as ribosomes to carry out protein synthesis.

Question 15

A patient undergoing chemotherapy for cancer develops an infection with cytomegalovirus, conclusively diagnosed by the presence of "owl's eye" viral nuclear inclusions in a liver biopsy. This is an example of a(n) ________.

Accepted Answer

The presence of "owl's eye" viral nuclear inclusions in a liver biopsy is a classic cytopathic effect of cytomegalovirus infection. This indicates that the virus is replicating and causing damage to the host cells. The immune response by the host may also be present, but is not the direct cause of the "owl's eye" appearance. Cytomegalovirus does not become a provirus, as it is a DNA virus that does not integrate into the host genome. Transformation of the host cell by cytomegalovirus refers to the virus causing the host cell to become cancerous, which is not the case in this scenario.

Question 16

Glycoprotein spikes are essential for mediating the release stage of the viral life cycle.

Accepted Answer

Glycoprotein spikes are essential for mediating the attachment and entry of viruses into host cells, not the release stage.

Question 17

You are running an experiment in calf serum, which cannot be autoclaved because proteins essential to your protocol will be denatured. You decide to filter sterilize the serum since the 0.22μm filter is small enough to block any bacteria that may contaminate your tissue culture. The success of this procedure hinges on the fact that ________.

Accepted Answer

The 0.22μm filter is designed to block bacteria but not viruses, so the success of the procedure in preventing bacterial contamination does not depend on the ability to block viruses. If the presence of viruses is inconsequential to the experiment, then the procedure can be considered successful despite not filtering out viruses.

Question 18

Viral genetic studies, vaccine development and clinical identification would not be possible without the ability to ________.

Accepted Answer

Culture is essential for studying viruses in the laboratory and for testing vaccines. Without the ability to culture viruses, it would not be possible to study their genetic makeup, replication, and transmission. The other options are not directly related to viral genetic studies, vaccine development, or clinical identification.

Question 19

An ideal antiviral drug would be one that ________.

Accepted Answer

An ideal antiviral drug would selectively target viral processes while causing minimal harm to the host cell. This would allow for effective treatment of the infection without causing further damage or harm to the patient. Choices B and C are not ideal because they would harm the host cell and potentially cause more harm than good. Choice D is also not ideal as it would prevent the host cell from functioning properly, leading to other issues.

Question 20

Prophages can be activated into viral replication and enter the lytic cycle.

Accepted Answer

Prophages can be activated by certain stimuli, such as stress or DNA damage, and undergo prophage induction, which leads to the lytic cycle and the production of new virus particles.

Quiz 5: Viral Structure and Multiplication