2.2 - ANTIVIRALS (ANTIVIRAL MEDICATIONS / TREATMENTS)
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Questions and Answers

A patient presents with flu-like symptoms. You want to confirm the presence of a specific viral antigen. Which of the following diagnostic methods would be most suitable?

  • Rapid antigen (correct)
  • PCR
  • Rapid antibody
  • Serology

What type of diagnostic method involves exposing a patient's sample to specific antibodies, aiming to capture and quantify the viral antigen present?

  • Serology
  • PCR
  • Rapid antibody
  • ELISA (correct)

Which of the following is NOT a method of disrupting the surface of a virus, particularly enveloped viruses?

  • Enzymes (correct)
  • Acids
  • Detergents
  • Lipids

Which of the following antiviral agents would likely be effective against a virus that relies on a specific enzyme for its replication?

<p>A nucleoside analog (A)</p> Signup and view all the answers

What is the primary function of thymidine kinase in viral replication?

<p>To convert nucleoside analogs into active antiviral forms (D)</p> Signup and view all the answers

You are treating a patient with a viral infection. You wish to prescribe an antiviral that targets the process of viral protein synthesis. Which of the following would be the most suitable choice?

<p>Ribavirin (B)</p> Signup and view all the answers

You want to prevent the spread of a particular virus by disrupting its surface proteins. Which of the following would be the most effective approach?

<p>Using a detergent (A)</p> Signup and view all the answers

What is the primary mechanism by which viruses attach to host cells?

<p>Binding of viral attachment proteins (VAPs) to host cell surface receptors. (A)</p> Signup and view all the answers

Which of the following is NOT a potential receptor for viral attachment?

<p>Nucleic acids (C)</p> Signup and view all the answers

Which of the following best describes the role of receptor antagonists in preventing viral attachment?

<p>They block the host cell's receptors, preventing viral attachment. (A)</p> Signup and view all the answers

Which of the following is NOT a common mechanism for the penetration of naked viruses into host cells?

<p>Membrane fusion (A)</p> Signup and view all the answers

Heparan sulfate and dextran are known to interfere with viral attachment to host cells. What is the mechanism by which these molecules block viral entry?

<p>They compete with viral attachment proteins for binding sites on host cell receptors. (D)</p> Signup and view all the answers

What is the main difference between the attachment and penetration stages of the viral lifecycle?

<p>Attachment involves binding to host cell receptors, while penetration involves entry into the host cell. (A)</p> Signup and view all the answers

How does the uncoating process differ between enveloped and naked viruses?

<p>Enveloped viruses uncoat their envelope at the host cell membrane, whereas naked viruses uncoat their capsid inside the cytoplasm. (D)</p> Signup and view all the answers

Which of these is NOT an example of an agent that can prevent viral attachment?

<p>Antibiotics (B)</p> Signup and view all the answers

The drug Maraviroc is used to treat HIV infections. What is its specific mechanism of action?

<p>It blocks the HIV co-receptor CCR5, inhibiting viral entry into the host cell. (B)</p> Signup and view all the answers

What is the primary function of matrix proteins (M proteins) in enveloped viruses?

<p>They assist in the assembly of the nucleocapsid into the virion. (A)</p> Signup and view all the answers

Which of the following post-translational modifications are NOT typically associated with viral proteins?

<p>Methylation (C)</p> Signup and view all the answers

How do interferons indirectly inhibit viral replication?

<p>By inducing the expression of cellular proteins that interfere with viral protein synthesis machinery. (A)</p> Signup and view all the answers

Which of the following statements accurately describes the release of non-enveloped viruses?

<p>It often results in the lysis of the host cell. (B)</p> Signup and view all the answers

Which of the following is a reason why mRNA synthesis is NOT considered a good target for antiviral drugs?

<p>Inhibiting viral mRNA synthesis often leads to severe side effects due to the disruption of cellular mRNA synthesis. (A)</p> Signup and view all the answers

Which of the following antiviral agents specifically targets the uncoating process of picornaviruses?

<p>Arildone (C)</p> Signup and view all the answers

What is the primary reason why the genomes of DNA viruses, excluding poxviruses, must be delivered to the nucleus?

<p>To utilize the cellular transcription machinery (B)</p> Signup and view all the answers

Which of these viral proteins is targeted by the antiviral agent Enfuvirtide?

<p>Fusion protein (A)</p> Signup and view all the answers

Which of the following viruses is NOT targeted by nucleoside analogs?

<p>Influenza A (B)</p> Signup and view all the answers

Which of the following statements accurately describes the mechanism of action of nucleoside analogs as antiviral agents?

<p>They inhibit viral DNA replication by preventing chain elongation or altering base pairing (C)</p> Signup and view all the answers

How does Amantadine and Rimantadine affect influenza A replication?

<p>They prevent the uncoating of the virus by neutralizing the pH of the vesicle (C)</p> Signup and view all the answers

Which of the following viral genomes are considered infectious nucleic acids?

<p>Positive-sense RNA viruses (B)</p> Signup and view all the answers

Which of the following is TRUE about the synthesis of viral proteins and nucleic acids?

<p>Early mRNA and nonstructural proteins are synthesized before genome replication (A)</p> Signup and view all the answers

Why are DNA viruses, except for poxviruses, able to replicate in the nucleus?

<p>They utilize the host cell's DNA polymerase (B)</p> Signup and view all the answers

Which of the following is a defining characteristic of DNA viruses, excluding poxviruses?

<p>They can establish latent infections (C)</p> Signup and view all the answers

Which of the following best describes the mechanism by which acyclovir inhibits viral DNA polymerase?

<p>Acyclovir is converted to its triphosphate form, which then competitively inhibits viral DNA polymerase. (B)</p> Signup and view all the answers

Why are HSV mutants lacking thymidine kinase activity resistant to acyclovir?

<p>These mutants lack the ability to convert acyclovir into its active form. (C)</p> Signup and view all the answers

What is the primary mode of action of ribavirin?

<p>Ribavirin induces mutations in the viral genome. (D)</p> Signup and view all the answers

Which of the following statements regarding phosphonoformate (PFA) is correct?

<p>PFA is a non-competitive inhibitor of herpesvirus DNA polymerase. (B)</p> Signup and view all the answers

What is the significance of the polarity of a viral RNA genome?

<p>The polarity influences the mechanism of viral replication and transcription. (B)</p> Signup and view all the answers

Why are most RNA viruses able to replicate in the cytoplasm?

<p>The nucleus is primarily involved in the replication of DNA viruses. (D)</p> Signup and view all the answers

What is the function of RNA-dependent RNA polymerase in negative-sense RNA viruses?

<p>It transcribes a positive-sense RNA strand from the negative-sense genome. (D)</p> Signup and view all the answers

Which of the following statements best describes the relationship between viral genome structure and replication?

<p>The structure of the viral genome dictates the mechanism of replication. (C)</p> Signup and view all the answers

Which of the following viruses is an exception to the general rule that RNA viruses replicate in the cytoplasm?

<p>Influenza virus (B)</p> Signup and view all the answers

What is the primary reason for the high mutation rate observed in RNA viruses?

<p>RNA viruses lack proofreading mechanisms during replication. (A)</p> Signup and view all the answers

Flashcards

Diagnostic Tests for Viral Infections

Tools like rapid antibody, rapid antigen, culture, PCR, serology, and ELISA to identify viral infections.

Virucidal Agents

Substances that can kill viruses by disrupting their structure.

Viral Life Cycle Steps

Nine stages including attachment, entry, replication, and release through which a virus infects a host cell.

RNA vs DNA Viruses

Differences between types of viruses based on their genetic material—RNA can be single or double-stranded; DNA can also be single or double-stranded.

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PCR in Viral Diagnosis

A rapid and precise technique to find viral DNA or RNA in samples.

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Culture Method for Viruses

Placing virus samples in cell cultures to check for cytopathic effects indicating infection.

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Role of Thymidine Kinase

An enzyme crucial for the activation of some antiviral medications, especially for herpesviruses.

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Virus Attachment

Virus VAPs bind to host cell receptors to initiate infection.

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Types of Receptors

Receptors on host cells may include proteins, carbohydrates, glycoproteins, or glycolipids.

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Enveloped Viruses

Viruses with lipid membranes use surface VAPs for attachment.

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Naked Viruses

Viruses with no lipid membrane use capsid regions to attach.

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Neutralizing Antibodies

Synthetic antibodies that bind to and neutralize VAPs.

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Receptor Antagonists

Drugs that block receptor activation to prevent viral attachment.

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HIV Co-receptor Blockers

Drugs like Maraviroc block HIV co-receptors necessary for entry.

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Penetration Phase

The process where viruses move along cell surfaces to enter.

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Uncoating Process

The disassembly of virions after they enter host cells.

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mRNA synthesis

Process of creating messenger RNA from DNA, essential for virus production.

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Antisense oligonucleotides

Short DNA or RNA pieces that bind to RNA, blocking protein synthesis.

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Interferons

Proteins that inhibit viral replication and protein synthesis in host cells.

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Matrix proteins (M proteins)

Proteins that assist in virus assembly and stabilize envelope interactions.

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Virus release mechanisms

Methods by which viruses exit host cells, including lysis and budding.

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Capsid Uncoating

Process where the viral capsid is removed to expose the genome for cellular machinery access.

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Viral Genome Delivery

DNA viruses (except poxviruses) need their genome delivered to the nucleus to replicate.

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Cytoplasmic RNA Viruses

Most RNA viruses remain in the cytoplasm for replication and do not enter the nucleus.

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Preventing Viral Uncoating

Methods to inhibit viral fusion proteins and prevent uncoating of viral capsids.

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Enfuvirtide

Drug that blocks HIV fusion proteins, preventing virus entry into cells.

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Nucleic Acid Synthesis

Processes involving the transcription of mRNA and replication of the viral genome in infected cells.

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Infectious Nucleic Acids

Naked genomes of some DNA and positive-sense RNA viruses that can replicate upon injection into cells.

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DNA Viruses Persistence

Many DNA viruses establish latent infections where the viral DNA resides in the host cell's nucleus.

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Nucleoside Analogues

Drugs that mimic nucleosides, blocking viral replication by preventing chain elongation or causing mutations.

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Phosphorylation of Nucleosides

Nucleoside analogs must be converted to triphosphate form to be effective against viruses.

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Acyclovir (ACV)

An antiviral drug phosphorylated by HSV thymidine kinase to inhibit viral DNA polymerase.

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HSV Thymidine Kinase

An enzyme that activates acyclovir by phosphorylation, crucial for the drug's function.

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Ribavirin

A purine nucleoside analogue that inhibits both RNA and DNA virus replication and causes hypermutation.

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Hypermutation

The increased mutation rate of a viral genome due to antiviral treatment.

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Non-nucleoside polymerase inhibitors

Drugs that inhibit polymerases without mimicking nucleotides, like Phosphonoformate.

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Phosphonoformate (PFA)

A noncompetitive inhibitor resembling pyrophosphate, targeting herpesvirus DNA polymerase.

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Positive-sense RNA

RNA that acts directly as mRNA for immediate protein synthesis upon entry.

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Negative-sense RNA

RNA that cannot be translated directly; serves as a template for creating positive-sense RNA.

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RNA-dependent RNA polymerase

An enzyme required by (-) RNA viruses for their replication process.

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Labile RNA

Refers to RNA's instability and short lifespan in the environment.

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Study Notes

Antiviral Drugs

  • Antivirals are drugs used to treat viral infections.
  • Development of antiviral drugs has seen a rise since the discovery of specific viruses.
  • Diagnostic methods like rapid antibody, rapid antigen tests, culture, PCR, serology, and ELISA are used to identify viral infections.
  • Preventing viral infections can involve disrupting viral structures (virions) and creating virucidal agents.
  • The viral life cycle has nine detailed steps, involving virus entry, uncoating, synthesis, assembly, and release.
  • Different viruses can utilize RNA or DNA.
  • Antiviral drugs target various steps in the viral life cycle.
  • Determining the mechanism of action (MOA) for antiviral drugs is important for selecting the correct drug for treating specific viral infections.
  • Thymidine kinase is an enzyme crucial to some antiviral drugs mechanisms.
  • There are various approved antiviral drugs targeting multiple viruses (HIV, HCV, Influenza, HSV, HBV, VZV, HCMV, RSV, HPV).
  • Some antiviral drugs don't need to be conventionally called "drugs" but also act by disrupting viral surfaces with lipids, detergents, or acids.
  • Citric acids can disrupt rhinovirus surface proteins.
  • Different viruses have methods that can be targeted, such as specific receptors, for viral treatment.
  • Synthetic neutralizing antibodies, receptor antagonists, and peptide analogs are among the agents that curb viral attachment mechanisms.
  • Some viral agents can penetrate and uncoat cells to produce infectious nucleic acids, which can be blocked by certain drugs.
  • Viral replication follows steps like genome replication, transcription, protein synthesis, and assembly.
  • Nucleoside analogs prevent viral genome replication and protein synthesis.
  • Some nucleoside analogues include acyclovir, ribavirin, and famciclovir.
  • Non-nucleoside enzyme inhibitors block polymerase action.
  • Different classes of viral inhibitors, such as protease inhibitors and neuraminidase inhibitors, help prevent virus assembly and release.
  • Some important scientists have contributed to antiviral research.

Viral Replication

  • Viruses must recognize and attach to the appropriate target cells.
  • Viruses typically infect cells with specific receptors.
  • Viruses penetrate and uncoat inside target cells.

Diagnostic Methods

  • ELISA and PCR are crucial for diagnosis and monitoring of viral infections.

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Antivirals - Microbiology Block 2 - Past Paper PDF

Description

Explore the essential concepts surrounding antiviral drugs, including their mechanisms of action, the viral life cycle, and diagnostic methods. This quiz covers a range of antiviral treatments for various viral infections and their importance in medicine. Test your knowledge on the latest advancements and approved drugs in antiviral therapy.

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