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Questions and Answers
What is the primary enzymatic activity of the medication Acyclovir targeting viral replication?
What is the primary enzymatic activity of the medication Acyclovir targeting viral replication?
Which of the following antiviral agents is categorized as an acyclic guanine nucleoside analogue?
Which of the following antiviral agents is categorized as an acyclic guanine nucleoside analogue?
What is a key characteristic that distinguishes Trifluridine from Idoxuridine in the context of herpes keratitis treatment?
What is a key characteristic that distinguishes Trifluridine from Idoxuridine in the context of herpes keratitis treatment?
Which antiviral drug's mechanism involves acting as an inorganic pyrophosphate, directly interacting with and inhibiting viral polymerases?
Which antiviral drug's mechanism involves acting as an inorganic pyrophosphate, directly interacting with and inhibiting viral polymerases?
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What is the primary method by which Foscarnet resistance develops in viruses?
What is the primary method by which Foscarnet resistance develops in viruses?
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Why do some antiviral drugs need to undergo phosphorylation to be effective?
Why do some antiviral drugs need to undergo phosphorylation to be effective?
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What is the effect of amino acid substitutions in viral proteins?
What is the effect of amino acid substitutions in viral proteins?
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What does the IC50 or IC90 value represent in the context of antiviral drug resistance?
What does the IC50 or IC90 value represent in the context of antiviral drug resistance?
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Why are RNA viruses, such as HIV and influenza, more prone to developing drug resistance?
Why are RNA viruses, such as HIV and influenza, more prone to developing drug resistance?
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According to the provided text, why is host cell immunity important in the treatment of viral infections with antivirals?
According to the provided text, why is host cell immunity important in the treatment of viral infections with antivirals?
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What is true regarding the relationship between in vitro and in vivo testing results for antiviral agents?
What is true regarding the relationship between in vitro and in vivo testing results for antiviral agents?
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What is a characteristic of current antiviral agents mentioned in the text?
What is a characteristic of current antiviral agents mentioned in the text?
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Why might prolonged use of an antiviral drug predispose to sequential acquisition of mutations?
Why might prolonged use of an antiviral drug predispose to sequential acquisition of mutations?
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Which of the following best describes the mechanism of action of enfuvirtide?
Which of the following best describes the mechanism of action of enfuvirtide?
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Maraviroc, an entry inhibitor, functions by targeting which specific protein?
Maraviroc, an entry inhibitor, functions by targeting which specific protein?
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What is the primary mechanism of action of raltegravir in preventing HIV replication?
What is the primary mechanism of action of raltegravir in preventing HIV replication?
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Emtricitabine, when converted to the triphosphate form, directly inhibits what specific viral enzyme?
Emtricitabine, when converted to the triphosphate form, directly inhibits what specific viral enzyme?
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Tenofovir functions to inhibit viral replication by means of what action?
Tenofovir functions to inhibit viral replication by means of what action?
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In the treatment of Hepatitis B, which of the following drugs functions as a nucleoside reverse transcriptase inhibitor (NRTI)?
In the treatment of Hepatitis B, which of the following drugs functions as a nucleoside reverse transcriptase inhibitor (NRTI)?
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Imiquimod, used for HPV treatment, works through which mechanism of action?
Imiquimod, used for HPV treatment, works through which mechanism of action?
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What is the primary target of drugs such as boceprevir, telaprevir, and simeprevir in the treatment of Hepatitis C?
What is the primary target of drugs such as boceprevir, telaprevir, and simeprevir in the treatment of Hepatitis C?
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Which of the following describes the role of Gardasil 9?
Which of the following describes the role of Gardasil 9?
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Why are reverse transcriptase (RT) drugs useful for treating Hepatitis B, which is a DNA virus?
Why are reverse transcriptase (RT) drugs useful for treating Hepatitis B, which is a DNA virus?
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Which of the following scientists is credited with identifying LAV as HIV?
Which of the following scientists is credited with identifying LAV as HIV?
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Which category of antiretroviral drugs includes both Nevirapine and Efavirenz?
Which category of antiretroviral drugs includes both Nevirapine and Efavirenz?
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Which of the following drug combinations is classified as an NRTI?
Which of the following drug combinations is classified as an NRTI?
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What is the primary mechanism of action for HIV protease inhibitors?
What is the primary mechanism of action for HIV protease inhibitors?
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How do NRTIs differ from NNRTIs in their mechanism of action related to the reverse transcriptase enzyme?
How do NRTIs differ from NNRTIs in their mechanism of action related to the reverse transcriptase enzyme?
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In the context of antiretroviral therapy, what does the term 'avir' typically indicate?
In the context of antiretroviral therapy, what does the term 'avir' typically indicate?
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What is the key difference between Nucleoside Reverse Transcriptase Inhibitors (NRTIs) and Nucleotide Reverse Transcriptase Inhibitors (NtRTIs)?
What is the key difference between Nucleoside Reverse Transcriptase Inhibitors (NRTIs) and Nucleotide Reverse Transcriptase Inhibitors (NtRTIs)?
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Reverse transcriptase uses which of the following as a substrate to generate DNA?
Reverse transcriptase uses which of the following as a substrate to generate DNA?
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Which of these is the function of Adefovir in the context discussed?
Which of these is the function of Adefovir in the context discussed?
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Which of the following best describes the general trend in resistance development in the provided list of anti-retroviral agents?
Which of the following best describes the general trend in resistance development in the provided list of anti-retroviral agents?
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Which antiviral drug is primarily indicated for CMV retinitis but is currently not available in the US?
Which antiviral drug is primarily indicated for CMV retinitis but is currently not available in the US?
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Which of the following best describes the mechanism of action of DNA or RNA base ‘analogues’ in preventing viral replication?
Which of the following best describes the mechanism of action of DNA or RNA base ‘analogues’ in preventing viral replication?
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Which antiviral agent is primarily used for influenza and is administered via inhalation?
Which antiviral agent is primarily used for influenza and is administered via inhalation?
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Which medication, used for both RSV and hepatitis C, functions as a broad-spectrum antiviral?
Which medication, used for both RSV and hepatitis C, functions as a broad-spectrum antiviral?
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Which of these antiviral medications is used explicitly for COVID-19 with investigational use noted?
Which of these antiviral medications is used explicitly for COVID-19 with investigational use noted?
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Which antiviral medication is a prodrug of penciclovir?
Which antiviral medication is a prodrug of penciclovir?
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Which antiviral agent is primarily used for the treatment of CMV and is administered intravenously?
Which antiviral agent is primarily used for the treatment of CMV and is administered intravenously?
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Which of the following medications is classified as a monoclonal antibody and is used to prevent severe RSV infections in infants?
Which of the following medications is classified as a monoclonal antibody and is used to prevent severe RSV infections in infants?
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Which of the following is not categorized primarily as an anti-herpetic agent but has shown efficacy against CMV?
Which of the following is not categorized primarily as an anti-herpetic agent but has shown efficacy against CMV?
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Which category of antiviral drugs includes both ‘Intron A’ and ‘Avonex’?
Which category of antiviral drugs includes both ‘Intron A’ and ‘Avonex’?
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Study Notes
Antiviral Agents
- Antiviral agents often affect host cell function.
- Effective agents typically target viral proteins.
- Mutations in viral proteins can lead to drug resistance.
- Current antiviral agents inhibit viral replication, but replication can continue after drug withdrawal.
- Effective host immune response is crucial for recovery.
- Current drugs may not eliminate latent or non-replicating viruses.
- Many drugs require phosphorylation to be effective.
- In vitro results may not always predict in vivo efficacy.
Biological Basis of Viral Resistance
- Drug resistance is defined as reduced susceptibility to a drug, measured by altered IC50 or IC90 values.
- Resistance often arises from specific mutations in the viral genome that affect the viral target protein or drug activator.
- RNA viruses, like HIV and influenza, exhibit high error rates during genome replication, leading to diverse viral variants and potential drug resistance.
- High-level resistance can require multiple mutations and insufficient viral suppression by antiviral drugs.
Viral Replication Cycle and Drug Targets
- Various antiviral drugs target different stages of the viral replication cycle within the host cell.
- Drugs can block attachment, penetration, uncoating, nucleic acid synthesis, and viral protein synthesis.
- Specific drugs can target various viral proteins and stages of the viral replication cycle.
Anti-herpetic and Anti-CMV Agents
- Idoxuridine, vidarabine, trifluridine, acyclovir, valacyclovir, ganciclovir, valganciclovir, penciclovir, famciclovir, foscarnet, cidofovir, and fomivirsen are used against herpes and CMV.
Nucleoside Analogs Mechanism
- Nucleoside analogs are antiviral drugs that incorporate into viral DNA, preventing further viral DNA replication.
- These drugs often require intracellular biochemical transformation before they can inhibit viral DNA polymerase.
Influenza and RSV Drugs
- Amantadine, rimantadine, zanamivir, oseltamivir, and baloxavir marboxil are used against influenza and RSV.
COVID-19 Drugs
- Baricitinib, remdesivir, tocilizumab, nirmatrelvir/ritonavir are used against COVID-19, some are under investigation.
Non-specific Antiviral Agents
- Interferons (alpha/beta) are used as non-specific antiviral agents for various conditions, including hepatitis B and C, Kaposi's sarcoma, and other malignancies.
Antiretroviral Agents
- NRTIs (nucleoside reverse transcriptase inhibitors) target reverse transcriptase by competing with triphosphate-binding sites and include zidovudine, lamivudine, and emtricitabine.
- NNRTIs (non-nucleoside reverse transcriptase inhibitors) bind to an allosteric site of reverse transcriptase, inhibiting the enzyme, and include nevirapine, delavirdine, efavirenz, and etravirine.
- Protease inhibitors target viral proteases and include ritonavir, saquinavir, indinavir, atazanavir, and darunavir.
HIV Entry, Fusion and Integration Inhibitors
- Enfuvirtide and Maraviroc target HIV entry and fusion, disrupting interactions with human cells by targeting CCR5 receptors.
- Raltegravir specifically blocks integration of HIV into host DNA.
HIV PrEP Drugs
- Emtricitabine/Tenofovir are used for pre-exposure prophylaxis (PrEP).
HBV, HPV & HCV Drugs
- Drugs for Hepatitis B virus (HBV) include NRTIs like telbivudine and entecavir.
- HPV is targeted by immune response modifiers like imiquimod and vaccines like Gardasil 9.
- Hepatitis C virus (HCV) has drugs such as Boceprevir, Telaprevir, and sofosbuvir/ledipasvir and Viekira.
Other Topics
- Mechanisms of action for RNA/DNA base analogs.
- Why ribavirin drugs are useful for HCV (an RNA virus), but not for HBV (a DNA virus).
- Drug resistance mechanisms in various viruses.
- Clinical applications and uses of different antiviral drugs.
- Adverse effects of antiviral drugs.
- Important diseases and viruses treated with antiviral drugs.
- Viruses associated with HSV I and HSV II.
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Description
Explore the mechanisms of antiviral agents and how they affect host cell functions. This quiz covers topics such as drug resistance, the role of viral mutations, and the biological basis behind antiviral efficacy. Understand how current treatments target viral replication and the challenges posed by viral resistance.