Viral Structure and Function Quiz
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Which viral component directly facilitates the penetration of a host cell membrane?

  • Envelope (correct)
  • Structural proteins
  • Capsid
  • Nucleic acid

    • What is the primary role of viral structural proteins?

  • To form the capsid and package the genome. (correct)
  • To encode information for the production of new virions.
  • To catalyze replication of the viral genome.
  • To suppress the host immune response.

    • Which of the following characteristics is common among influenza viruses, rhinoviruses and coronaviruses?

  • Non-segmented genome
  • ssRNA genome (correct)
  • Enveloped capsid
  • dsDNA genome

    • Which of the following viruses utilizes CD4 as a cell receptor?

    <p>HIV-1 (D)</p> Signup and view all the answers

    What is the estimated percentage of acute respiratory disease (ARD) cases in the United States caused by viral infections?

    <p>Approximately 80% (A)</p> Signup and view all the answers

    Influenza viruses use HA to attach to which receptor on respiratory epithelial cells:

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

    What is the typical mode of transmission for most viral respiratory infections?

    <p>Respiratory droplets or hand transfer (C)</p> Signup and view all the answers

    Which of the following is an example of a non-structural protein?

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

    Which receptor does the SARS-CoV-2 Spike glycoprotein interact with to facilitate entry into host cells?

    <p>ACE2 receptor (C)</p> Signup and view all the answers

    What is the primary function of the ciliated epithelium in the upper respiratory tract?

    <p>Trapping debris in mucus and moving it towards the GI tract. (D)</p> Signup and view all the answers

    Which structural change occurs in the respiratory epithelium as it transitions from the upper to the lower respiratory tract?

    <p>The cells become shorter and lose cilia and mucus-producing cells. (B)</p> Signup and view all the answers

    What is a key characteristic of the Coronavirus genome?

    <p>It is comprised of a positive-sense RNA genome. (B)</p> Signup and view all the answers

    Which method is suitable for detecting active SARS-CoV-2 infection?

    <p>Molecular (RT-PCR) test (B)</p> Signup and view all the answers

    Which part of the respiratory tract is located above the larynx?

    <p>Sinuses, nasal cavity, and pharynx. (B)</p> Signup and view all the answers

    Which of the following is a structural component of coronaviruses?

    <p>Spike (S) glycoprotein (C)</p> Signup and view all the answers

    What is the purpose of the respiratory epithelium losing cilia as it transitions to the lower respiratory tract?

    <p>To improve efficiency of oxygen and carbon dioxide diffusion. (A)</p> Signup and view all the answers

    Where does the coronavirus acquire its envelope?

    <p>Endoplasmic Reticulum-Golgi intermediate compartment (C)</p> Signup and view all the answers

    Which receptor is primarily targeted by the SARS-CoV-2 virus for cell entry?

    <p>ACE2 receptor (C)</p> Signup and view all the answers

    Besides the respiratory system, where else are ACE2 receptors found?

    <p>Kidney and myocardium of the heart (D)</p> Signup and view all the answers

    How is SARS-CoV-2 primarily transmitted?

    <p>Through respiratory droplets (A)</p> Signup and view all the answers

    Which of the following viruses is non-enveloped?

    <p>Parvovirus B19 (B)</p> Signup and view all the answers

    Where does initial SARS-CoV-2 viral replication typically occur?

    <p>Nasopharyngeal and/or oropharyngeal cells. (C)</p> Signup and view all the answers

    Which of the following coronaviruses had the highest fatality rate?

    <p>MERS-CoV (C)</p> Signup and view all the answers

    What is the glycoprotein on the SARS-CoV-2 virus that facilitates binding to host cells?

    <p>S (Spike) Glycoprotein (B)</p> Signup and view all the answers

    Which of these is a part of/located in the lower respiratory tract?

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

    What is the function of viral RNA polymerase in coronaviruses?

    <p>To replicate the viral RNA genome (A)</p> Signup and view all the answers

    Which of the following is a characteristic of the lower respiratory tract compared to the upper respiratory tract?

    <p>Shorter epithelial cells (D)</p> Signup and view all the answers

    In which part of the cell does Coronavirus replication and assembly occur?

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

    Which HPV type is commonly associated with plantar warts?

    <p>HPV 1 (C)</p> Signup and view all the answers

    Which of the following HPV types is LEAST likely to be associated with common warts?

    <p>HPV 16 (D)</p> Signup and view all the answers

    Which of the following is a less common HPV type associated with cervical cancer?

    <p>HPV 31 (C)</p> Signup and view all the answers

    Which HPV type is commonly associated with epidermodysplasia verruciformis?

    <p>HPV 17 (C)</p> Signup and view all the answers

    Which of the following HPV types is commonly associated with oral papilloma?

    <p>HPV 11 (A)</p> Signup and view all the answers

    Which HPV type is often implicated in conjunctival papilloma?

    <p>HPV 11 (D)</p> Signup and view all the answers

    Which HPV type is commonly associated with laryngeal papilloma?

    <p>HPV 6 (A)</p> Signup and view all the answers

    What structural feature is characteristic of coronaviruses?

    <p>An envelope with club-shaped protein peplomers forming a corona. (C)</p> Signup and view all the answers

    Which of the following is a primary mode of transmission for coronaviruses?

    <p>Respiratory droplets and fecal-oral routes. (C)</p> Signup and view all the answers

    The E2 or spike glycoprotein of coronaviruses is significant because it functions as the:

    <p>Viral attachment protein (VAP). (C)</p> Signup and view all the answers

    What is the typical tropism of coronaviruses within a host?

    <p>Respiratory tract or gastrointestinal tract epithelium. (C)</p> Signup and view all the answers

    The relatively high rate of diversity observed in coronaviruses is thought to be linked to:

    <p>Production of multiple, individual mRNAs during replication. (C)</p> Signup and view all the answers

    What direct effect do 'common' coronavirus infections have on the respiratory tract?

    <p>Disruption of cilia function on the epithelial cells. (B)</p> Signup and view all the answers

    Why are the club-shaped protein peplomers of coronavirus significant, besides giving the virus its distinctive appearance?

    <p>They protect against acidic gastrointestinal conditions. (C)</p> Signup and view all the answers

    The optimal growth temperature for 'common' coronaviruses is:

    <p>33°C (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the coronavirus genome?

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

    What types of infection are possible with coronaviruses, depending on the infecting strain?

    <p>Lytic, latent and transforming infections (A)</p> Signup and view all the answers

    Flashcards

    Nucleic Acid

    The genetic material that encodes information necessary for virus reproduction, either DNA or RNA.

    Capsid

    A protein shell that packages and protects viral nucleic acid between infections.

    Structural Proteins

    Proteins that form the capsid and can be involved in virus attachment or packaging.

    Non-Structural Proteins

    Proteins needed for virus replication and assembly but not part of the virus's structure.

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    Envelope

    A lipid bilayer that surrounds some viruses, helping in cell attachment and penetration.

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    Transmission of Respiratory Viruses

    Mainly through respiratory droplets or hand transfer, with an incubation of 1-14 days.

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    Common Respiratory Viruses

    Includes influenza, RSV, coronaviruses, and more, causing acute respiratory disease (ARD).

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    VAP (Viral Attachment Proteins)

    Proteins that allow viruses to attach to specific host cell receptors.

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    Coronaviruses

    Largest RNA viruses, positive-sense RNA genome, helical nucleocapsid.

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    Spike (S) glycoprotein

    Protein on the surface of coronaviruses that binds to ACE2 receptors.

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    ACE2 receptor

    Receptor in upper and lower respiratory tract for SARS-CoV-2 binding.

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    SARS-CoV-2

    The virus responsible for COVID-19, part of the coronavirus family.

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    Transmission method of SARS-CoV-2

    SARS-CoV-2 is transmitted through respiratory droplets.

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    Infection rate of COVID-19

    COVID-19 caused approximately 178 million cases globally.

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    Fatality rates of SARS and MERS

    SARS had a 10% fatality rate; MERS had a 35% fatality rate.

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    Testing for SARS-CoV-2

    Molecular (RT-PCR) and antigen tests available to detect SARS-CoV-2.

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    Antibody test

    Test for past exposure to SARS-CoV-2.

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    Virus assembly

    Coronaviruses assemble in the cytoplasm and acquire an envelope from ER-Golgi.

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    Plantar wart

    A type of skin wart caused by HPV types 1 and 2.

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    Common wart

    Skin warts commonly caused by HPV types 2 and 4, found on various body parts.

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    Flat wart

    A smooth, slightly elevated skin lesion caused mainly by HPV types 3 and 10.

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    Cervical intraepithelial neoplasia

    A precancerous condition associated with high-risk HPV types, notably 16 and 18.

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    Condyloma acuminatum

    Anogenital warts often linked to HPV types 6 and 11.

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    Anogenital warts

    Warts in the genital and anal regions typically caused by HPV.

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    Laryngeal papilloma

    Benign tumors in the larynx caused by HPV types 6 and 11.

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    Coronaviridae

    Family of viruses that are enveloped with a positive-sense ssRNA genome.

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    Peplomers

    Club-shaped protein spikes on the virus envelope that form a crown appearance.

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    Tropism

    The affinity of a virus for specific host tissues, such as the respiratory or GI tract.

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    Transmission Mechanisms

    Methods through which coronaviruses spread, including respiratory droplets and fecal-oral routes.

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    Viral Attachment Protein (VAP)

    Proteins like E2 or spike glycoprotein that facilitate pathogen adherence to host cells.

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    mRNA Diversity

    The process of generating multiple mRNAs from a single viral genome, contributing to genetic diversity.

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    Infectious Disease Mechanism

    Coronaviruses can cause lytic, latent, or transforming infections based on the strain.

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    Epithelial Disruption

    Coronaviruses infect respiratory epithelial cells and disrupt their cilia function.

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    Optimal Growth Temperature

    The temperature at which coronaviruses grow best, around 100°F.

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    Upper Respiratory Epithelium

    The epithelium above the larynx, including sinuses and nasal cavity, with taller cells containing cilia and mucus-producing cells.

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    Function of Cilia

    Cilia in the upper respiratory epithelium help move trapped debris towards the GI tract for neutralization.

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    Lower Respiratory Epithelium

    The epithelium below the larynx with shorter cells lacking cilia and mucus cells, facilitating gas diffusion.

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    SARS-CoV-2 Entry

    SARS-CoV-2 enters the body through the upper respiratory and possibly the gastrointestinal tract.

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    Viral Replication Locations

    SARS-CoV-2 replicates in upper airways and can spread to lower respiratory tract components.

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    Bronchial Epithelial Cells

    Cells in the lower respiratory tract, part of the bronchi that can be infected by viruses.

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    Alveolar Macrophages

    Immune cells located in the alveoli that defend against pathogens in the lungs.

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    Mucus Production

    Mucus traps debris in the upper respiratory epithelia, aiding in air filtration.

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    Diffusion of Gases

    Shorter cells in the lower respiratory tract optimize the diffusion of oxygen and carbon dioxide between alveoli and blood.

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    Study Notes

    MABS Microbiology

    • Course covers virology, respiratory viruses, hepatitis viruses, papilloma and polyoma viruses, and human retroviruses.

    Course Instructional Objectives

    • MCRO 3.1: Students will describe the taxonomy, structure, and function of coronaviruses, including transmission, pathogenesis, stages of viral infection, viral gene expression, viral replication, effects at the cellular level and/or human immune response.
    • MCRO 3.2: Students will describe the taxonomy, structure, and function of influenza viruses, including transmission, pathogenesis, stages of viral infection, viral gene expression, viral replication, effects at the cellular level, human immune response and treatment
    • MCRO 3.3: Students will describe the taxonomy, structure and function of RSV, including transmission, pathogenesis, effects at the cellular level, and human immune response.
    • MCRO 3.4: Students will describe the taxonomy, structure, and function of adenoviruses, including transmission, pathogenesis, viral gene expression, viral replication, effects at the cellular level and/or human immune response.
    • MCRO 3.5: Students will describe the taxonomy, structure, and function of retroviruses, especially HIV-1, including transmission, pathogenesis, stages of viral infection, viral gene expression, viral replication, effects at the cellular level, and human immune response and/or treatment.
    • MCRO 3.6: Students will describe the taxonomy, structure, function of papillomaviruses, including transmission, pathogenesis, stages of viral infection, viral gene expression, viral replication, and the likelihood of HPV to cause cancer.
    • MCRO 3.7: Students will describe the taxonomy, structure, and function of hepatitis viruses, focusing on transmission, pathogenesis, and cellular effects.

    Review: Components of a Virus

    • Viral Component: Nucleic acid, Capsid, Structural proteins, Non-structural proteins, Envelope.
    • Role in Viral Life Cycle: Encodes information for progeny virions, protein shell protecting nucleic acid, contains/packages viral nucleic acid, form capsid, package genome, and/or attachment proteins, required for replication, for assembly, or facilitate disease progression, lipid bilayer for viral attachment, penetrates host cell membrane.
    • Example: DNA or RNA, icosahedral, helical, complex, Matrix, nucleocapsid, VP, Polymerase, helicase, protease, transcription factors.

    Respiratory Viruses

    • Respiratory disease accounts for ~75-80% of acute morbidity in the United States.
    • Most illnesses are viral, typically transmitted by respiratory droplets or hand-transfer.
    • Incubation period is generally 1-4 days, but up to 14 days.
    • The viruses commonly associated with acute respiratory disease (ARD) include parainfluenza viruses, influenza viruses, respiratory syncytial virus (RSV), coronaviruses, adenoviruses, rhinoviruses, human metapneumovirus (hMPV), and bocaviruses.

    Overview: Coronaviruses

    • Coronaviruses are large RNA viruses with a helical nucleocapsid and a lipid bilayer envelope.
    • Viral Spike (S) glycoprotein, membrane, and envelope glycoproteins are essential.
    • Replication occurs in the cytoplasm, acquiring an envelope from ER-Golgi membranes.
    • Three novel coronaviruses have been identified: SARS-CoV-1, MERS-CoV, and SARS-CoV-2 (COVID-19).
    • COVID-19, while initially limited, became a pandemic.

    Respiratory Epithelium

    • Upper respiratory tract epithelium is composed of taller, ciliated epithelial cells, with mucus-producing cells.
    • Aids in debris clearance within inhaled air.
    • Lower respiratory tract epithelium is composed of shorter, non-ciliated cells to facilitate better O2 & CO2 diffusion.

    SARS-CoV-2

    • SARS-CoV-2 enters the body through the respiratory tract (nasopharynx, oropharynx), airways, and alveolar epithelial cells.
    • Viral Spike (S) glycoprotein's RBD interacts with ACE2 receptor.
    • ACE2 receptors are in the respiratory system, kidney, and myocardium.

    Coronavirus Characteristics

    • Linear, positive sense ssRNA
    • Envelope with club-shaped protein peplomers, which protect against acidic conditions (unique among enveloped viruses).

    Viral Infection and the Immune System

    • The body's innate immune response involves phagocytes, T-cells, and the release of cytokines.

    Immune System & Coronaviruses

    • Recruited leukocytes (lymphocytes, monocytes, and neutrophils) are essential immune responses to viral infections.
    • Cell-mediated immunity plays a role in controlling severe and reducing viral infection, though antibody-mediated can result in more lingering protection.
    • Viral infections can lead to tissue damage which, in turn, makes the body more susceptible to bacterial infections.

    Influenza Virus

    • Influenza is classified into three types (A, B, and C), based on antigenic differences.
    • Influenza A viruses cause more extensive epidemics than other subtypes.
    • Influenza B viruses are more stable and cause more localized outbreaks.
    • Influenza C, less frequent, commonly affects humans and pigs.

    Pathogenicity and Virulence

    • Pathogenicity describes a microbe’s ability to cause disease within a person.
    • Virulence describes the degree of pathogenicity among strains of the same microbe.

    Antigenic Shift vs. Antigenic Drift

    • Antigenic drift: Gradual, slight changes in viral surface proteins (HA & NA) due to mutations, resulting in less effective antibodies.
    • Antigenic shift: Abrupt, major changes in viral surface proteins via re-assortment of the viral genome from different sources (typically host exchange from animals).

    Influenza Virus Summary

    • Family is Orthomyxoviridae.
    • Genome is linear ssRNA.
    • Enveloped with helical capsid.
    • Transmission is by respiratory droplets.
    • Tropism primarily affecting respiratory tract epithelium.
    • Major surface glycoproteins are HA (hemagglutinin) and NA (neuraminidase)
    • 18 HA and 11 NA subtypes are known, and some cause significant human disease.

    Influenza Life Cycle

    • Viral RNA transcription and genome replication occur in host cell's nucleus.
    • Nucleocapsids assemble in the nucleus, then assemble/bud from plasma membrane in cytoplasm.

    Influenza Disease

    • Can cause different degrees of severity, from mild cold to fatal pneumonia.
    • Severity can be influenced by pre-existing immunity and the specific influenza strain.

    Influenza Treatment and Prevention

    • Symptomatic treatment (e.g. acetaminophen, antihistamines).
    • Antiviral medication (e.g. amantadine, rimantadine, oseltamivir, zanamivir) can be effective if given early.
    • Prevention via vaccinations, which are updated to combat prevalent strains.

    Classification of RNA Viruses

    • All RNA viruses are single-stranded, except for the Reoviridae family
    • All negative sense RNA viruses are enveloped with helical capsid structure.
    • All non-enveloped RNA viruses have an icosahedral capsid.

    Paramyxoviridae (e.g., Respiratory Syncytial Virus (RSV))

    • RSV primarily infects bronchi, bronchioles, and alveoli of the lung, resulting in croup, bronchitis, or pneumonia in infants.
    • RSV is spread via respiratory secretions and has an incubation period of 4-6 days.

    Respiratory Syncytial Virus (RSV)

    • Leading cause of fatal acute respiratory infection in infants and young children.
    • Two serotypes circulating during the RSV season (October-March).
    • Viral attachment proteins (attachment G glycoprotein and fusion F glycoprotein).
    • Tropism is limited to the respiratory epithelium, with no viremia (absence of virus in the bloodstream).
    • Transmission is through respiratory droplets and direct contact.
    • At high risk include premature infants and elderly.

    Adenovirus

    • Adenoviruses are dsDNA viruses, generally non-enveloped, helical capsid.
    • They are highly resistant to disinfectants.
    • Frequently cause respiratory infections (types 1, 2, 3).
    • Can cause conjunctivitis, and other non-respiratory infections.

    Retroviruses

    • Retroviruses are RNA viruses, using reverse transcriptase to convert their RNA genome into DNA during replication, and then are integrated into the host cell's genome.

    Human Immunodeficiency Virus (HIV)-1

    • A retrovirus, with two copies of positive-sense RNA.
    • Viral attachment protein gp160 (gp120 + gp41)
    • CD4 receptors are an initial target, along with co-receptors CCR5 and CXCR4 in cells (T-cells, macrophages, DCs).

    Hepatitis Viruses

    • A diverse group of viruses affecting liver inflammation, known for their variety regarding genomes (RNA or DNA viruses).
    • A to E are caused by different viruses, with varied transmission routes, leading to acute or chronic illnesses.
    • Hepatitis B is a DNA virus, while others are RNA.

    Hepatitis A (HAV)

    • Fecal-oral transmission of a picornavirus.
    • Short incubation (~1 month).
    • Primarily associated with acute hepatitis.
    • No chronic sequelae (e.g. no long-term complications).

    Hepatitis B (HBV)

    • DNA virus (Hepadnavirus family).
    • Primarily transmitted via body fluids (e.g. blood, sexual contact).
    • Long incubation (3 months).
    • Frequently resulting in chronic infections.
    • Potential for severe complications, including cirrhosis and hepatocellular carcinoma (liver cancer)

    Hepatitis C (HCV)

    • RNA virus (Flavivirus).
    • Transmitted through blood-to-blood contact.
    • Long incubation (~6-7 weeks).
    • Predominantly a chronic infection.
    • High risk of cirrhosis and hepatocellular carcinoma.

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    Description

    Test your knowledge on the structural components of viruses and their roles in penetrating host cells. This quiz covers various aspects of viral infections, focusing on respiratory viruses like influenza and coronaviruses. Explore concepts such as viral receptors, structural proteins, and modes of transmission.

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