HE432 Test 2 Practice Questions (High Yield Quiz Based)

What is the term for when the addition of a nucleotide analog causes the growing nucleic acid to stop growing?

Chain termination

Which antiviral mechanism involves incorporation that results in chain termination?

Nucleoside/nucleotide analogues

Which drug works by competing with guanosine for incorporation into viral DNA and causes chain termination?

Acyclovir

Which viral enzyme is inhibited by acyclovir?

Virus specific DNA polymerase

Which antiviral strategy blocks viral entry into host cells?

Entry inhibitors

Which type of entry inhibitor blocks fusion of viral and host membranes?

Fusion inhibitors

Which antiviral approach uses monoclonal antibodies to block viral entry?

Entry inhibitors

Which nucleic acid-based antiviral directly interferes with regulatory proteins?

Decoy oligonucleotides

What is the mechanism of decoy oligonucleotides?

Compete with viral genome or mRNA for binding so regulatory proteins bind decoy sequence instead

Which nucleic acid-based approach targets viral RNA and forms dsRNA?

Antisense inhibition

What happens to dsRNA formed during antisense inhibition?

Digested by DICER → RNAi pathway

Which nucleic acid-based antiviral blocks transcription by forming a triple helix?

Antigene oligonucleotides

Which antiviral drugs are preferentially selected by reverse-transcriptase?

Nucleoside or nucleotide analogs

Which antiviral therapy uses tenofovir and emtricitabine?

PrEP/TRUVADA

Which type of reverse-transcriptase inhibitor binds directly to RT and prevents activity?

NNRTIs

Why is combination therapy used in antiretroviral treatment?

To mitigate resistance

Which stage of the viral life cycle is blocked by neuraminidase inhibitors?

Release

Which viral protein is targeted by oseltamivir (Tamiflu)?

Neuraminidase

Why does inhibiting neuraminidase stop viral spread?

Prevents virus detachment from the cell

Which antiviral mechanism targets the host immune response?

Immunostimulation

What immunostimulant is used as a broad-spectrum antiviral?

Interferon

Which antiviral approach can target latent viruses?

Nucleic acid-based approaches

Most antiviral therapies are broad-spectrum

False

Why are most antiviral drugs not broad-spectrum?

Drugs affect only one or a few related viruses

Why is antiviral toxicity a major issue?

Difficult to separate viral metabolism from cellular metabolism

Why do viruses rapidly develop resistance to antivirals?

High mutation rate (especially RNA viruses)

Which characteristic best describes viral replication?

Replication - mainly host machinery

Which characteristic best describes bacterial replication?

Replication - independent of host

Why is it difficult to target viruses without harming host cells?

Virus uses the cell's machinery and metabolic processes

Which antiviral strategy would still work if the virus is latent?

Nucleic acid-based approaches

Which antiviral mechanism would NOT require active viral replication?

Oligonucleotides

Which factor most determines whether a newly introduced virus will persist in humans?

Efficiency of transmission between humans

Which scenario best explains why a highly virulent virus may fail to spread?

Killing the host rapidly can limit transmission opportunities

Which route of transmission involves arthropod vectors?

Mosquito-mediated transmission

Emerging infectious diseases are defined only as infections caused by completely new viruses

False

Which scenario best illustrates an emerging infectious disease?

A virus whose incidence has increased over time

What is the term for when too many mutations occur in a viral genome leading to nonfunctional viruses?

Error catastrophe

Which antiviral drug induces errors in genome replication leading to error catastrophe?

Ribavirin

Why do antiviral drugs rapidly lose effectiveness against viruses?

High mutation rate

Which mechanism allows reverse transcriptase to avoid binding NRTIs while still binding natural nucleotides?

NRTI discrimination

What type of mutation is most commonly responsible for NRTI resistance?

Single base pair changes

What mechanism allows HIV to remove incorporated NRTIs from the growing DNA strand?

Increased proofreading ability

What type of antiviral strategy reduces resistance by requiring multiple mutations to occur simultaneously?

Combination therapy

What is the definition of combination therapy?

Treating an infection with more than one antiviral

Why does combination therapy reduce resistance?

Decreased chance that a strain will acquire all mutations necessary

Which antiviral treatment strategy is particularly important for HIV due to rapid resistance?

Combination therapy

What is the term for when two drugs interact negatively and reduce each other's effects?

Antagonistic effect

What is the term for when two drugs produce a combined beneficial effect?

Additive effect

What is the term for when two drugs together have a stronger effect than separately?

Synergistic effect

What is the name of highly active antiretroviral therapy used for HIV?

HAART

How many drugs are typically included in HAART?

At least 3 drugs

What is a major limitation of HAART therapy?

Drug toxicity and poor treatment compliance

What type of antiviral strategy is used before exposure to prevent infection?

Pre-exposure prophylaxis

What is the abbreviation for pre-exposure prophylaxis?

PrEP

What type of antiviral strategy is used after exposure to prevent infection?

Post exposure prophylaxis

What is the abbreviation for post exposure prophylaxis?

PEP

Which antiviral drug is a guanosine nucleoside that inhibits mRNA capping?

Ribavirin

Why can many antiviral drugs not cure infections?

Long term infections

Why do symptoms not correlate with viral infection?

Symptoms are related to immune response

When do antiviral drugs tend to work best?

If present before the virus infects

What is a limitation of prophylactic antiviral treatment?

Long term treatment effects, patient compliance, cost

What example shows treating symptoms rather than infection?

Hydrocortisone reduces cold sore but increases viral titres

Which antiviral drug is a prodrug that becomes a ribonucleotide analogue inhibiting RNA polymerase?

Remdesivir

What therapy involves giving plasma from a recovered patient to an infected patient?

Convalescent plasma therapy

What does CRISPR stand for?

Clustered Regularly Interspaced Short Palindromic Repeats

Which CRISPR enzyme cuts DNA?

Cas9

Which CRISPR enzyme cuts RNA?

Cas13

What molecule guides Cas enzymes to the target sequence?

sgRNA

What sequence is required for CRISPR-Cas to cut DNA?

PAM sequence

What limits where CRISPR can target DNA?

Presence of PAM sequences

What DNA repair pathway introduces errors after CRISPR cutting?

Non-homologous end joining

What DNA repair pathway uses a donor template to repair DNA?

Homology directed repair

What does SDSA stand for?

Synthesis dependent strand annealing

What does DSBR stand for?

Double strand break repair

What is one antiviral application of CRISPR-Cas?

Modify host or viral factors

Which viral form can CRISPR target in infected cells?

Proviral DNA

What is a major limitation of CRISPR antiviral therapy?

Off-target editing

What is another limitation of CRISPR antiviral therapy?

Delivery challenges

What viral adaptation can reduce CRISPR effectiveness?

Viral escape mutations

What immune-related limitation exists for CRISPR therapies?

Immune responses to components

Most antiviral drugs are broad-spectrum

False

What is a key limitation of antiviral drugs regarding spectrum?

No broad-spectrum antiviral drugs

Which antiviral is an exception with activity against multiple RNA viruses?

Ribavirin

Which factor best determines whether a virus persists in humans?

Efficiency of transmission between humans

Why might a highly virulent virus fail to spread widely?

Killing the host rapidly can limit transmission opportunities

Which route of transmission involves arthropod vectors?

Mosquito-mediated transmission

Which scenario best represents an emerging infectious disease?

A virus whose incidence has increased over time

Emerging infectious diseases are only caused by completely new viruses

False

PCR can determine if a virus is actively replicating

False

Which diagnostic method can determine if a virus is actively replicating?

Detection of viral RNA or replicative intermediates

Which type of cytopathic effect results in multinucleated cells?

Syncytia

What causes syncytia formation in infected cells?

Fusion of infected cells

Marburg virus is an arbovirus

False

What defines an arbovirus?

Virus transmission via biting insects and ticks

Which virus transmission route involves arthropods?

Vector-borne transmission

Zika virus causes microcephaly in fetuses because it infects which cells?

Cells responsible for neuronal development

Why does Zika virus infection during pregnancy cause developmental defects?

Infection of neuronal development cells

All viruses are culturable in the lab

False

Why are some viruses not culturable in the lab?

Require specific host conditions

Which diagnostic method does not require prior knowledge of the virus?

Electron microscopy