Viral Replication and Antiviral Targets MCQs PDF

viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 1. Which of the following viral families would require the action of an RNA-dependent RNA polymerase during replication? Retroviridae Herpesviridae Parvoviridae Poxviridae Togaviridae Togaviridae Poxviridae, Par...

viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 1. Which of the following viral families would require the action of an RNA-dependent RNA polymerase during replication? Retroviridae Herpesviridae Parvoviridae Poxviridae Togaviridae Togaviridae Poxviridae, Parvoviridae, and Herpesviridae families contain DNA viruses, which are replicated by making DNA from DNA and RNA from that same DNA. They would not need an RNA-dependent RNA polymerase. Retroviridae contain RNA viruses but remember that retroviruses are first reverse-transcribed from RNA into DNA, and then the RNA genome is made from that DNA template. The only one that makes RNA directly from RNA during replication would be the togavirus. 2. Question 2 HTLV, a retrovirus 1 / 1 pts Of these options, all but HTLV A physician orders an RT-PCR test as are DNA viruses. Creating a part of the workup to diagnose a patient. DNA copy of RNA using the Which of the following viruses might be RT (reverse transcriptase) enphysician be concerned the patient has? zyme, and then amplifying that Cytomegalovirus (CMV), a herpesvirus via PCR, would be best used HTLV, a retrovirus to identify the presence of RNA Parvovirus B19, a parvovirus viruses, of which HTLV is the Chickenpox (Varicella-zoster virus), a only example here. herpesvirus 3. Question 3 Release occurs by budding 1 / 1 pts An enveloped virus that buds A research group is studying the replica- through the cell membrane detion of a novel enveloped viral pathogen. rives the envelope from that The group is interested in understanding membrane; it therefore cannot why viral particles are never found intra- be complete until it exits the cellularly, only extracellularly. Which of cell. Release by lysis or exocytothe following might explain that finding? sis would suggest that the virus Release occurs by exocytosis must already have it's mem1 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 Release occurs by cell lysis Release occurs by budding There is a gap between the end of the eclipse and latent periods brane before exit. The eclipse period marks the first production of complete virus particles, so if this period ends prior to the latent period, which marks the appearance of these particles extracellularly, that would indicate that complete particles are present intracellularly. 4. Question 4 1 / 1 pts Which virus is most likely susceptible to detergents? Rhinovirus, a picornavirus Parvovirus B19 Human herpesvirus 1 Human herpesvirus 1 Naked viruses are resistant to most detergents, as they have no lipid component. A detergent would have to be quite strong to denature protein. The only enveloped virus family in the options are the herpesviruses. All others are likely to be resistant. 5. Question 5 1 / 1 pts If a pharmaceutical company were to develop an antiviral drug aimed at neutralizing a virus by inhibiting its fusion protein, which stage of the viral replication cycle would most likely be affected? Binding Integration Entry Assembly Entry Fusion of viral and host cell membranes is part of the viral entry process. Attachment will already have occurred, and assembly occurs later. Integration refers to the genome of the virus becoming incorporated into the host cell genome, not the viral particle itself becoming integrated into the host cell. It is possible that a fusion protein may also play a role in another phase of the replication process, but not commonly. 6. Question 6 1 / 1 pts A research group is studying a viral Early protein Early proteins are those involved in nucleic acid synthesis, most 2 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 protein that produces copies of the viral genome. What descriptor would most likely fit this protein? Nucleoprotein Early protein Immediate early protein Late protein Fusion protein Integrase protein notably the nucleic acid polymerases. Late proteins form the structure of the virion, for example, capsid proteins, fusion proteins, or attachment proteins. Immediate early proteins redirect host cell function, for example, a viral protein that acts as a transcription factor and causes the host RNA polymerase to prefer viral promoters. Fusion proteins are involved in combining the viral envelope with a host membrane (either the plasma membrane or an endosome membrane), allowing the envelope to be removed. Integrases are found in a few types of viruses and incorporate the viral genome into the host genome. They do not produce copies of the viral genome. A viral nucleoprotein attaches to the genome, helping with protection from degradation, determining location, or controlling replication. It does not replicate the genome. 7. Question 7 1 / 1 pts A researcher is studying a new virus, and is trying to determine its tropism. She attempts to infect a variety of cell lines and looks for the location of virions using confocal fluorescence microscopy. In one cell line, she finds virions lining the surface of the cells, but no viral protein inside the cells. What phenomenon would best explain this finding? The cell is susceptible but not permissive If the virus particles are binding to the surface, but not entering the cell, then the cell line is susceptible, but not permissive. If the adhesin did not recognize the receptor, binding to the surface would not occur. It is irrelevant what the genome is, or whether the virus is enveloped or not. 3 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 The cell is susceptible but not permissive The virus is a -ssRNA virus The virus adhesin does not match the cellular receptor The virus is a naked virus 8. Question 8 1 / 1 pts An 8-month-old girl is brought to her pediatrician with a runny nose, sneezing, and cough. Her mother states that the baby is not able to nurse as efficiently as before due to her symptoms, which precipitated their visit. The child has no fever or signs of dehydration. The physician diagnoses her with the common cold, which is likely picornaviral in origin. What is most likely a component of the causative agent? Lipid bilayer Polysaccharide capsule Protein capsid Lipopolysaccharide Peptidoglycan cell wall Protein capsid The common cold is a viral infection (if you didn't know this, not a problem, and now you do!). Peptidoglycan and lipopolysaccharide are bacterial components, while polysaccharide capsules are found on various microbe types (but not viruses). Protein capsids are found in all viruses, whereas lipid bilayers are only seen in some. This makes capsid the best answer. 9. Question 9 1 / 1 pts A pharmaceutical company is developing "achoozimab", a monoclonal antibody antiviral therapeutic that interrupts early steps in the replication cycle of rhinoviruses, a type of picornavirus that is a major cause of common colds. What viral component is most likely being targeted by the therapeutic agent? RNA Capsid protein Spike glycoprotein Capsid protein Early steps in replication include attachment, entry, and uncoating, which in a naked virus such as a picornavirus are going to be mediated by the capsid protein. Antibodies against the capsid could block any or multiple of these steps, rendering the infection non-productive. Picornaviruses such as rhinoviruses, being naked, do not have membrane lipids (which would like- 4 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 DNA Envelope lipid ly not be a great target for an antibody anyhow) or spike glycoproteins (glycoproteins usually being associated with membrane proteins), and the DNA and RNA are irrelevant to these early stages of the infection. 10. Question 10 1 / 1 pts A 34-year-old woman presents to an urgent care clinical with frequent vomiting and diarrhea over the past 2 days. The clinic has seen numerous cases of a similar illness over the past few weeks. She is advised to remain quarantined and have her home cleaned with a bleach-based agent to prevent transmission to her family, as the causative agent is not inactivated by most cleaning agents and will remain infectious on surfaces for long periods of time. Based on this description, what is a feature of the most likely causative agent? Filamentous capsid DNA genome Spike glycoproteins Single-stranded RNA genome Non-enveloped capsid Non-enveloped capsid The persistence of the virus in the environment indicates resistance to drying, while resistance to common cleaners indicates detergent resistance. These suggest the virus is naked, as an envelope would likely render it sensitive to these (and other) stresses. Therefore, the capsid is not covered by an envelope, and it does not have spike glycoproteins. You may not have noticed, but all the filamentous viruses are enveloped (as are all the -ssRNA viruses...). The composition of the genome is not directly relevant, as the outer layers determine protection. 11. Question 11 1 / 1 pts A researcher is studying an emerging infectious disease. A novel agent is isolated that, when injected into a susceptible animal model, is able to cause the same disease. The novel agent is characterized further after being propagated in a cell line in the lab. Which finding Infectious agent cannot be purified soon after infecting the cell line Once a virion infects a susceptible and permissive host cell, it uncoats to release the genome. If there is an envelope, this will have been removed by fusing with a cell membrane, releasing 5 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 would indicate that the causative agent is a virus? Infectious agent cannot be purified soon after infecting the cell line Isolated ribosomes contain 23S rRNA molecules Purified agent contains a dsDNA genome Purified agent contains only proteins Treatment with membrane-disrupting disinfectants prior to inoculation prevents infection the capsid, and the capsid proteins will detach from themselves and from the nucleic acid they are protecting, releasing the nucleic acid. Therefore, the agent no longer exists as a single thing that can be purified; this is known as the eclipse phase. Viral components might be recoverable, but not the entire virion. While some viruses have a double-stranded DNA genome, other infectious agents such as bacteria and eukaryotes do as well. So, this finding would not indicate that the agent was a virus, just that it could be one. Viruses do not contain ribosomes. 23s rRNA is found in the large subunit of bacterial ribosomes. Some viruses have membranes, but so do other infectious agents such as bacteria and eukaryotes, and the membranes of many of these could be susceptible to these agents. So, this finding would not indicate that the agent is a virus, just that it might be an enveloped virus. Viruses must contain at least protein and nucleic acid. An infectious agent made only of protein is a prion. 6 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 12. Question 12 1 / 1 pts A novel viral pathogen is being studied to determine its tropism. Findings include: Respiratory cells but not kidney cells The respiratory cells appear to be both susceptible to the virus (capsid component can attach) and permissive (the genome can 1. A viral capsid protein can bind to both direct the production of viral parrespiratory and kidney cells. ticles). This suggests that respiratory cell infection would be suc2. Virions are produced by respiratory cessful. While the virion would cells when the viral genome is introbe expected to attach to the kidduced directly into the cytoplasm. ney cells, which indicates that these cells are susceptible to the 3. Virions are not produced by kidney virus, the cells cannot replicate cells when the viral genome is introthe virus from the genome, induced directly into the cytoplasm. dicating they are not permissive. A productive infection of kidney Which cell type(s) would be expected to cells would not likely be producsupport infection with this virus? tive. Kidney cells but not respiratory cells Respiratory cells but not kidney cells Neither respiratory nor kidney cells Both respiratory and kidney cells 13. Question 13 1 / 1 pts What are the components of a poliovirus virion? ssRNA, polymerase, capsid & envelope ssRNA, ribosome & capsid ssRNA & capsid ssRNA, capsid & envelope ssRNA, ribosome, capsid & envelope ssRNA, polymerase, capsid 7 / 10 ssRNA & capsid Poliovirus is a picornavirus, which means it is a naked, +ssRNA virus. Therefore, it would not package a pre-formed RNA-dependent RNA polymerase in the virion, as this enzyme could be translated directly from the +ssRNA genome, which is equivalent to mRNA, upon uncoating into the cytoplasm. Ribosomes used in viral replication come from the host cell. They are not viral in ori- viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 gin. A naked virus does not have an envelope. 14. Question 14 RNA molecule 1 / 1 pts The genome of a -ssRNA virus A 3-year-old girl is brought to an urgent is the reverse complement of the care clinic with an erythematous, blanch- sequence that makes "sense" for ing, maculopapular rash on her face, translation. The first viral moleneck, and trunk that appeared overnight. cule that is produced after inShe has a fever that started about 5 days fection for a -ssRNA virus must ago and then had a cough. Her eyes ap- therefore be a sense, or positive, pear red. Her history indicates that she strand of RNA; this must precede is unvaccinated due to religious beliefs. the production of any protein. She is diagnosed with measles, which is Since the virus cannot produce caused by a paramyxovirus. What virally the protein needed for the proencoded component would be produced duction of this sense strand (the first during the replication process? viral RNA-dependent RNA polyDNA molecule merase), the virion must carry a Viral attachment protein pre-formed RdRp enzyme within RNA molecule it. It is attached to the -ve sense RNA-dependent RNA polymerase genome, and produces that +ssNucleoprotein RNA molecule as the first viral product. 15. Question 15 1 / 1 pts A 34-year-old woman reported to her physician that she had experienced genital burning pain for the past 2 days. The pain and burning were worse during urination and accompanied by fever and malaise. Physical examination revealed multiple blisters and ulcerative lesions in the vaginal area. A presumptive diagnosis of herpes genitalis was made, and acyclovir was prescribed. Which of the following steps of the viral growth cycle was most likely primarily inhibited by the prescribed drug? 8 / 10 Transcription Acyclovir is a first-line agent for herpes genitalis. Oral therapy speeds up the healing and reduces the frequency of reactivation episodes. Acyclovir must be activated by phosphorylation, then the triphosphate compound competitively inhibits viral DNA polymerase, thus blocking DNA synthesis. Transcription is therefore inhibited. viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 Entry Proteolytic cleavage Uncoating Transcription Assembly Translation 16. Question 16 1 / 1 pts A 30-year-old man with AIDS was recently diagnosed with cytomegalovirus retinitis, and therapy with ganciclovir was started. Two weeks later, the disease was not much improved, and the ophthalmologist decided to add a drug that, unlike ganciclovir, can directly inhibit DNA polymerase without requiring activation by phosphorylation. Which of the following drugs was most likely prescribed? Ribavirin Oseltamivir Foscarnet Acyclovir Amantadine Foscarnet Foscarnet is an inorganic pyrophosphate analogue that inhibits viral DNA polymerase, RNA polymerase, and HIV reverse transcriptase directly without requiring activation by phosphorylation. The drug, given only by intravenous injection, is effective in the treatment of cytomegalovirus (CMV) infections, including retinitis, colitis, and esophagitis. It is often given together with ganciclovir because it has been shown that the combination is superior to either agent alone in delaying the progression of retinitis. Adverse effects can be severe, and renal impairment may occur in up to 30% of patients. 17. Question 17 1 / 1 pts A 5-month-old baby girl born prematurely at 31 weeks gestation was found to have bronchopulmonary dysplasia and required oxygen administration. A respiratory syncytial virus (RSV) outbreak was ongoing in the community, and the pediatrician decided to prescribe Palivizumab. Which of the follow- Entry Palivizumab is a humanized monoclonal antibody that binds to the A antigen site on the F surface protein of respiratory syncytial virus (RSV) preventing viral entry into cells. It is approved for the prevention of RSV infection in high-risk infants and children, 9 / 10 viral replication and antiviral targets MCQs Study online at https://quizlet.com/_ehlgp6 ing steps of the viral growth cycle was such as those with pulmonary most likely primarily inhibited by the pre- dysplasia, as in this case. scribed drug? Proteolytic cleavage Assembly Transcription Translation Uncoating Entry 18. Question 18 1 / 1 pts A 71-year-old man was brought to the emergency department because of a fever (103.2°F, 39.6°C), chills, dyspnea, and generalized aches in his back and legs. The social history of the patient was significant for an outbreak of flu in the community. A clinical diagnosis of influenza was made, and treatment with a neuraminidase inhibitor was started. Which of the following actions most likely mediated the therapeutic effect of the drug in the patient's disease? Prevention of virus release from infected cells Inhibition of viral transcription Blockade of fusion of the virus with the host cell Inhibition of viral protein synthesis Inhibition of viral proteolytic cleavage 10 / 10 Prevention of virus release from infected cells Oseltamivir is an inhibitor of neuraminidase, an enzyme produced by influenza A and B viruses. The enzyme cleaves sialic acid residues from cell surfaces, promoting the release of newly formed viruses from the surface of infected cells. By blocking the enzyme, these drugs inhibit virus release from the infected cells.