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General Properties of Viruses
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General Properties of Viruses

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Questions and Answers

Which of the following statements accurately describes the structure of the SARS-CoV-2 virus?

  • The virus is composed of nucleocapsid, membrane, envelope, and spike proteins. (correct)
  • The primary structural protein is the nucleocapsid, which aids in viral entry.
  • It contains only a single-stranded RNA and does not have any structural proteins.
  • SARS-CoV-2 is a double-stranded DNA virus with a lipid capsule.

    • What is the primary method through which SARS-CoV-2 enters host cells?

  • Using the S glycoprotein to bind to the ACE2 receptor followed by membrane fusion. (correct)
  • Through endocytosis after binding to the ACE2 receptor.
  • By fusing with the mitochondrial membrane.
  • Direct penetration of the membrane without receptor binding.

    • Which of the following is considered an indirect method of transmission for SARS-CoV-2?

  • Direct person-to-person contact.
  • Touching contaminated surfaces followed by face touching. (correct)
  • Respiratory droplets from coughing.
  • Aerosolized particles that remain airborne.

    • Which of the following types of vaccines is NOT classified as an mRNA vaccine?

    <p>AstraZeneca.</p> Signup and view all the answers

    What is the primary target tissue for SARS-CoV-2 infection?

    <p>Respiratory tract, particularly the alveolar epithelial cells.</p> Signup and view all the answers

    Which non-pharmaceutical intervention is least effective in preventing SARS-CoV-2 transmission?

    <p>Consuming high amounts of vitamin C.</p> Signup and view all the answers

    What is the primary reason viruses cannot replicate independently?

    <p>They require host cell machinery and enzymes.</p> Signup and view all the answers

    Which of the following best describes the size range of viruses?

    <p>20-300 nm</p> Signup and view all the answers

    What protective structure do viruses have that aids in entry into host cells?

    <p>Capsid</p> Signup and view all the answers

    Which group of organisms can viruses infect?

    <p>Unicellular organisms and higher plants and animals</p> Signup and view all the answers

    Why are viruses resistant to antibiotics?

    <p>They are not composed of cells.</p> Signup and view all the answers

    What type of nucleic acid can be found in viruses?

    <p>Both DNA and RNA</p> Signup and view all the answers

    Which of the following substances can effectively combat viruses?

    <p>Chlorine</p> Signup and view all the answers

    What distinguishes obligate intracellular parasites from other types?

    <p>They require living cells to grow and reproduce.</p> Signup and view all the answers

    What is a major group of viruses that specifically infect bacteria called?

    <p>Bacteriophage</p> Signup and view all the answers

    Which geometric symmetry is characterized by having 20 equilateral triangular faces?

    <p>Icosahedron</p> Signup and view all the answers

    What structural feature always surrounds helical animal viruses?

    <p>Viral envelope</p> Signup and view all the answers

    What is the primary function of the capsid in viruses?

    <p>Protection of nucleic acid</p> Signup and view all the answers

    Which type of viruses are described as not fitting into the standard symmetry classifications?

    <p>Complex viruses</p> Signup and view all the answers

    What distinguishes helical viruses from icosahedral viruses?

    <p>Their geometric shape</p> Signup and view all the answers

    In which scenario does a virus have a naked capsid?

    <p>When it lacks a viral envelope</p> Signup and view all the answers

    What type of symmetry is represented by a coiled configuration of the capsid?

    <p>Helical</p> Signup and view all the answers

    Which of the following statements about virus shapes is true?

    <p>The arrangement of capsid subunits determines the virus shape.</p> Signup and view all the answers

    Which description best fits a virus with irregular configurations that do not adhere to typical symmetry?

    <p>Complex virus</p> Signup and view all the answers

    What characteristic is unique to RNA viruses in relation to their capsid?

    <p>Their capsid forms a coil shape.</p> Signup and view all the answers

    Which method can effectively inactivate viruses by altering their nucleic acids?

    <p>Photodynamic inactivation</p> Signup and view all the answers

    What characteristic makes the single-stranded genome more susceptible to inactivation than the double-stranded genome?

    <p>Reactivity with formaldehyde</p> Signup and view all the answers

    Which of the following statements regarding detergents is correct?

    <p>Anionic detergents disrupt capsids into separate polypeptides.</p> Signup and view all the answers

    Under what conditions do enteroviruses typically transmit?

    <p>Through both respiratory and fecal-oral routes</p> Signup and view all the answers

    What is the primary effect of extreme alkaline conditions on viruses?

    <p>It destroys all viruses.</p> Signup and view all the answers

    What concentration of ethanol is generally recognized as more effective against viruses?

    <p>50-70%</p> Signup and view all the answers

    Why are antibiotics ineffective against viruses?

    <p>Viruses lack cell walls targeted by antibiotics.</p> Signup and view all the answers

    Which of the following treatments acts primarily on the lipid component of viral envelopes?

    <p>Ether</p> Signup and view all the answers

    What is necessary for antimicrobial agents like chlorine to effectively kill viruses?

    <p>Utilizing them at high concentrations.</p> Signup and view all the answers

    Which characteristic applies to naked viruses regarding their stability?

    <p>They can withstand drying and high detergent concentrations.</p> Signup and view all the answers

    What is the primary infection caused by Varicella Zoster Virus (VZV)?

    <p>Chickenpox</p> Signup and view all the answers

    Which of the following viruses is classified as a flavivirus?

    <p>Yellow fever virus</p> Signup and view all the answers

    How do enveloped viruses such as VZV maintain infectivity?

    <p>By remaining intact and wet</p> Signup and view all the answers

    What characterizes a reactivation of the Varicella Zoster Virus?

    <p>Vesicular rash along a dermatome</p> Signup and view all the answers

    Which group is NOT considered high-risk for influenza virus infection?

    <p>Individuals with healthy immune systems</p> Signup and view all the answers

    What diagnostic method is not typically used for detecting Varicella Zoster Virus (VZV)?

    <p>Rapid diagnostic tests</p> Signup and view all the answers

    Which antiviral medication is NOT used to treat Varicella Zoster Virus infections?

    <p>Ribavirin</p> Signup and view all the answers

    What is a significant symptom of influenza virus infection?

    <p>Body aches</p> Signup and view all the answers

    With what structural characteristic does Varicella Zoster Virus (VZV) entry into host cells occur?

    <p>Interaction between glycoproteins and host cell receptors</p> Signup and view all the answers

    Study Notes

    General Characteristics of Viruses

    • Unique, smallest infectious agents ranging from 20-300 nm in size.
    • Composed of a nucleic acid core (DNA or RNA) and a protective protein coat called a capsid.
    • Obligate intracellular parasites; require living cells for replication and lack metabolic machinery.
    • Not susceptible to antibiotics, but can be inactivated by antimicrobial chemical agents (e.g., chlorine, alcohol).
    • Infect a variety of hosts, including unicellular organisms, plants, and animals.

    Major Viral Groups

    • Plant viruses: Infect plants.
    • Insect viruses: Infect insects.
    • Bacteriophage: Viruses that infect bacteria.
    • Animal viruses: Infect vertebrates.

    Virus Structure

    • Virions contain either DNA or RNA and can vary in shape:
      • Icosahedral: Regular structure with 20 triangular faces.
      • Helical: Coil-shaped structure found in many RNA viruses.
      • Complex: Irregular structures that do not fit traditional symmetries.
    • Capsids can be naked or enveloped.

    Mode of Transmission

    • Transmission routes depend on virus type; naked viruses are robust against environmental challenges and transmitted via respiratory and fecal-oral routes.
    • Enveloped viruses are fragile and transmitted through moist environments such as respiratory droplets or bodily fluids.
    • Vulnerable populations include infants, children, and the elderly.

    Viruses of Medical Importance

    • Notable examples include Flaviviruses, Ebola, Measles, Rubella, Polio, Mumps, and SARS-CoV-2.

    Varicella Zoster Virus (VZV)

    • A double-stranded DNA virus belonging to the Herpesvirus family.
    • Causes chickenpox (primary infection) and shingles (reactivation).
    • Diagnosed via clinical presentation or laboratory tests (PCR, serology).
    • Prevention includes vaccination (live attenuated for chickenpox, recombinant for shingles).

    Influenza Virus

    • Causes acute respiratory infections.
    • Spreads through respiratory droplets; symptoms include fever, cough, and malaise.
    • High-risk groups include pregnant women and individuals with chronic conditions.
    • Diagnosis through clinical evaluation and laboratory tests; prevention focuses on hygiene and vaccination.

    SARS-CoV-2 (COVID-19)

    • An enveloped, positive-sense, single-stranded RNA virus of the Betacoronavirus genus.
    • Transmission occurs through respiratory droplets, contact with surfaces, or aerosols.
    • Primary targets are cells in the respiratory tract; the S protein binds to ACE2 receptors for entry.
    • Preventive measures include vaccination (mRNA and viral vector options) and non-pharmaceutical interventions (mask-wearing, hygiene).

    Photodynamic Inactivation and Chemical Agents

    • Vital dyes can penetrate viruses, enhancing susceptibility to inactivation by light.
    • Ultraviolet and high-energy particles are effective for sterilization.
    • Chemical agents like ether and detergents can disrupt viral envelopes, while formaldehyde inactivates viral infectivity.

    Antibiotic and Antimicrobial Knowledge

    • Antibiotics have no effect on viruses; chlorinated solutions are effective for viral eradication.
    • Concentration of alcohol is crucial; 50-70% ethanol is more effective against certain viruses.

    Pathogenesis Overview

    • Viral infection involves receptor binding, fusion with the host cell, replication of viral components, assembly of new virions, and eventual release, often damaging host cells in the process.

    These notes capture essential characteristics and important aspects of viruses, serving as a comprehensive study guide.

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    Description

    Explore the unique characteristics and properties of viruses in this quiz. Learn about their structure, their role as obligate intracellular parasites, and their infectious nature. Test your knowledge on the fundamental aspects that distinguish viruses from other microorganisms.

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