Question 1

A drug is designed which blocks the attachment of the Epstein Barr virus to its receptor.Which physiological effect might be observed in patients receiving this medication?

Accepted Answer

A

Question 2

Most non-enveloped animal viruses enter the host cell by

Accepted Answer

Most non-enveloped animal viruses enter the host cell through receptor-mediated endocytosis, where the virus binds to specific receptors on the cell surface and is then engulfed by the cell in a vesicle.

Question 3

The influenza virus gains entry into a host cell by

Accepted Answer

The influenza virus gains entry into a host cell through receptor-mediated endocytosis, where the virus binds to specific receptors on the cell surface, and is then engulfed by the cell through invagination of the cell membrane. Once inside the cell, the virus uncoats and releases its genetic material, which then undergoes replication and transcription to take over the host cell's machinery for virus production.

Question 4

Which of the following techniques would most efficiently identify a virus causing an emerging disease?

Accepted Answer

The answer of Which of the following techniques would most...

Question 5

Which of the following cellular functions is unlikely for a host cell receptor recognized by a virus?

Accepted Answer

A virus is unlikely to recognize a host cell receptor that is involved in the cellular function of a glycolytic enzyme. This is because viruses typically do not mimic or use the cellular metabolic pathways of the host cell for their own replication. Instead, they rely on host cell machinery and processes for viral entry, genome replication, and virion assembly. Receptors involved in hormone signaling, ionic channel transport, active transport, and cell signaling are more commonly targeted by viruses as they play important roles in cell-cell interactions and viral tropism.

Question 6

E.coli strain K12 is susceptible to infection by phage T2.T2 binds to K12 via two attachment proteins.These two proteins specifically bind to the following two host cell receptor proteins found on the surface of strain K12.

Accepted Answer

Phage T2 binds to strain K12 through two attachment proteins, which specifically bind to OmpF and lipopolysaccharide receptors found on the surface of the host cell. This is the only option given that includes OmpF and lipopolysaccharide as receptor proteins, so it must be the correct choice.

Question 7

A non-enveloped virus will have its attachment proteins present in its:

Accepted Answer

Non-enveloped viruses do not have an envelope, so their attachment proteins must be present on the surface of their capsid. Capsid spikes are protein structures that protrude from the surface of the virus and are responsible for mediating attachment to host cells.

Question 8

The second step in viral replication is entry.For bacteriophage,entry usually involves

Accepted Answer

Bacteriophages typically inject their nucleic acid directly into the bacterial cell, bypassing the need for mechanisms like endocytosis or membrane fusion.

Question 9

Plant viruses often gain entry into host cells by

Accepted Answer

Plant viruses often gain entry into host cells through injury caused by insects, which act as vectors and transmit the virus from one plant to another. The virus enters the plant cell through wounds caused by the feeding of the insect vector. This is an example of mechanical transmission.

Question 10

The influenza virus is most likely to bind to a host cell receptor with amino acid sequence similarity to:

Accepted Answer

The influenza virus is known to bind to host cells using hemagglutinin protein that specifically recognizes and binds to sialic acid receptors on the surface of host cells. Therefore, the most likely choice of amino acid sequence similarity for the host cell receptor is sialic acid.

Question 11

Antibody produced in response to a viral infection is able to neutralize viral attachment by

Accepted Answer

Antibodies are proteins that are produced by the body's immune system in response to an infection. One of the ways in which antibodies can neutralize viruses is by binding to viral attachment proteins, which are proteins on the surface of the virus that allow it to attach to and enter host cells. By binding to these attachment proteins, antibodies can prevent the virus from attaching to the host cell and therefore prevent infection. Option A and B refer to steps in viral replication; Option C is an indirect way of combating the virus by recruiting immune cells to clear the infection, whereas Option E is incorrect because the host cell receptor doesn't interact with viral antibodies.

Question 12

Most non-enveloped viruses enter the host cell by receptor-mediated endocytosis.The virus or its nucleic acid is able to leave the endosome and enter the cytoplasm

Accepted Answer

Non-enveloped viruses often utilize their capsid proteins to form pores in the endosomal membrane, allowing their nucleic acid to enter the cytoplasm.

Question 13

Structurally,the drug Fuzeon is similar to:

Accepted Answer

The answer of Structurally,the drug Fuzeon is similar to:

...

Question 14

The influenza virus gains entry into a host cell by an endocytotic process.The viral nucleocapsid leaves the endosome and enters the cytoplasm through a membrane fusion mechanism.Fusion of the viral envelope with the endosomal membrane is facilitated by

Accepted Answer

Hemagglutinin undergoes a conformational change to expose a fusion protein, which facilitates fusion of the viral envelope with the endosomal membrane, allowing the viral nucleocapsid to enter the cytoplasm.

Question 15

The SARS virus is most likely to bind a receptor similar in amino acid sequence to:

Accepted Answer

The SARS virus, specifically SARS-CoV, binds to the ACE2 receptor, which is similar in amino acid sequence to Bgp1^a (also known as CEACAM1), a receptor used by some coronaviruses.

Question 16

The ability of a virus or bacteriophage to specifically attach to a host cell occurs through the interactions of the viral attachment protein with the host cell receptor.This binding determines

Accepted Answer

The host range of a virus is determined by its ability to specifically attach to a host cell receptor. Different viruses have different viral attachment proteins that interact with different host cell receptors, thus determining the range of host species that a virus can infect.

Other choices are incorrect because viral DNA or RNA replication, the mechanism of viral entry, and the presence of an envelope are all determined by factors within the virus itself and not solely by the binding of the viral attachment protein with the host cell receptor.

Question 17

The viral attachment protein specifically binds to a host cell receptor.All of the following are examples of known host cell receptors except

Accepted Answer

DNA is not typically found on the surface of a host cell and therefore cannot serve as a receptor for viral attachment proteins. The other options, proteins, glycoproteins, lipopolysaccharides, and sialic acids, are all known to serve as host cell receptors for various viruses.

Question 18

Fuzeon is an antiviral drug that prevents membrane fusion for entry into the cell by HIV.The mode of action for this drug is

Accepted Answer

Fuzeon (enfuvirtide) is a fusion inhibitor, which means it works by preventing HIV from fusing with the CD4 host cell membrane. Specifically, it binds to the gp41 protein of HIV, which is responsible for mediating membrane fusion with the host cell. By binding to gp41, Fuzeon blocks the fusion process and prevents HIV from entering the host cell. Options A, B, C, and E are not correct because they do not accurately describe the mode of action of Fuzeon.

Question 19

Most likely,"host specificity" of a virus is determined by

Accepted Answer

Host specificity of a virus is determined by its ability to attach to host cell receptors. This is mediated by interactions between viral attachment proteins and host cell receptors. The specificity of the interaction between the two determines the host range of the virus. Viruses that are able to recognize and bind to receptors on a particular host cell can infect and replicate within those cells, leading to the onset of infection.

Question 20

Antiviral drugs such as Maraviroc that act at the level of host recognition are designed to

Accepted Answer

Antiviral drugs, such as Maraviroc, that act at the level of host recognition, interfere with the attachment of the virus to the host cell receptor. This prevents the virus from entering the host cell, stopping the infection process.

Quiz 8: Viral Replication Strategies