Virology Basics Quiz
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Questions and Answers

What is the primary function of viral glycoproteins during influenza virus infection?

  • They assemble into new virions.
  • They replicate viral RNA.
  • They release viral proteins.
  • They attach the virus to host epithelial cells. (correct)

Which process allows some enveloped viruses to deliver their internal components directly to the cytoplasm of a host cell?

  • Fusion (correct)
  • Endocytosis
  • Lysis
  • Budding

What mechanism do non-enveloped viruses commonly use to exit the host cell after replication?

  • Cell lysis (correct)
  • Endocytosis
  • Budding
  • Exocytosis

During the replication cycle of a virus, which step immediately follows penetration?

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

What type of viruses utilize host cell membranes to form an envelope during their release phase?

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

What is the first step in the viral life cycle?

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

What type of nucleic acid is generated during the synthesis of viral components?

<p>mRNA and viral proteins (C)</p> Signup and view all the answers

Which of the following best describes the replication cycle of the HIV virus?

<p>It undergoes cell fusion to enter the host. (D)</p> Signup and view all the answers

What are viroids primarily composed of?

<p>Naked single-stranded RNA without protein coat (A)</p> Signup and view all the answers

What is the primary function of the outer viral proteins?

<p>Mediate attachment to specific receptors (D)</p> Signup and view all the answers

Which of the following correctly describes prions?

<p>Entirely made of protein without nucleic acids (D)</p> Signup and view all the answers

Which statement about the replication of viruses is true?

<p>The entire virus enters the cells during the penetration phase. (A)</p> Signup and view all the answers

What type of genetic material does a retrovirus contain?

<p>Single-stranded RNA with reverse transcriptase (C)</p> Signup and view all the answers

What occurs during the biosynthesis phase of virus replication?

<p>Viral proteins and nucleic acids are synthesized. (A)</p> Signup and view all the answers

How do naked viruses typically release their components from host cells?

<p>By cell lysis (D)</p> Signup and view all the answers

Which characteristic is NOT used in virus classification?

<p>Presence of metabolic enzymes (B)</p> Signup and view all the answers

What type of nucleic acid do viruses possess?

<p>Either DNA or RNA (A)</p> Signup and view all the answers

What is the primary function of the virus capsid?

<p>To protect the viral genome and help entry into host cells (A)</p> Signup and view all the answers

Which of the following is a characteristic of a ds RNA virus?

<p>Contains double-stranded RNA (C)</p> Signup and view all the answers

What structural component distinguishes an enveloped virus from a naked virus?

<p>Presence of a lipid bilayer membrane (D)</p> Signup and view all the answers

How are viral genomes generally categorized?

<p>By nucleic acid type and structure (D)</p> Signup and view all the answers

What are capsomeres?

<p>The structural components of the virus capsid (A)</p> Signup and view all the answers

Which shape is NOT one of the common capsid structures of viruses?

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

What role do glycoprotein spikes on a virus serve?

<p>Host cell attachment (D)</p> Signup and view all the answers

What are the main components of a virus particle?

<p>Internal core and protein coat (B)</p> Signup and view all the answers

Why are viruses classified as obligate intracellular parasites?

<p>They require a host cell to replicate. (C)</p> Signup and view all the answers

Which statement correctly describes the size of viruses?

<p>They range from about 10 to 300 nanometers. (B)</p> Signup and view all the answers

What type of nucleic acid can viruses contain?

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

What is the purpose of the capsid in a virus?

<p>To provide protection to the genome (B)</p> Signup and view all the answers

Which of the following statements is true regarding viruses?

<p>They lack ribosomes and cannot synthesize proteins. (C)</p> Signup and view all the answers

In which decade were the first photographs of viruses obtained?

<p>1940s (A)</p> Signup and view all the answers

What defines a virus as acellular?

<p>It does not have a cellular structure. (C)</p> Signup and view all the answers

What is a common symptom of infectious mononucleosis caused by Epstein-Barr Virus?

<p>Swollen lymph glands (B)</p> Signup and view all the answers

What is the primary mode of transmission for the Epstein-Barr Virus?

<p>Intimate contact with saliva (A)</p> Signup and view all the answers

Which influenza virus type is known for causing pandemics?

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

What characterizes the structure of coronaviruses?

<p>Crown-like spikes (B)</p> Signup and view all the answers

Which of the following outcomes is commonly associated with a reactivation of Epstein-Barr Virus?

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

Which strain of coronavirus was first identified in Saudi Arabia in September 2012?

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

What percentage of all colds are estimated to be caused by coronaviruses?

<p>15-30% (D)</p> Signup and view all the answers

How does the Middle East Respiratory Syndrome (MERS) primarily spread from one person to another?

<p>Through the air by coughing and sneezing (B)</p> Signup and view all the answers

What is the incubation period for MERS-CoV infection?

<p>2-14 days (D)</p> Signup and view all the answers

Which of the following is NOT a symptom of MERS-CoV infection?

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

Which type of vaccine contains weakened forms of the virus?

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

What complications can arise from a MERS-CoV infection?

<p>Pneumonia and kidney failure (D)</p> Signup and view all the answers

Which type of vaccine is produced using biotechnology and genetic engineering techniques?

<p>Subunit vaccine (D)</p> Signup and view all the answers

What is the primary treatment approach for patients with MERS?

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

Why are antiviral drugs difficult to develop?

<p>Viruses replicate within host cells. (C)</p> Signup and view all the answers

Which of the following pre-existing conditions is NOT associated with increased risk for severe MERS?

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

Flashcards

What are viruses?

Viruses are tiny particles, smaller than bacteria, that can cause diseases.

Why are viruses not considered alive?

Viruses are not considered living organisms because they lack a cellular structure and cannot reproduce independently. They require a host cell to multiply.

What is the structure of a virus?

Viruses contain either DNA or RNA as their genetic material, which is enclosed within a protein coat called a capsid.

How are viruses classified?

Viruses are classified based on factors such as the type of nucleic acid they contain (DNA or RNA), the shape of their capsid, and the type of host cell they infect.

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How do viruses replicate?

A virus requires a host cell to replicate. It can only multiply inside a living cell by using the cell's machinery.

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What is a viral envelope?

Some viruses have an additional outer layer called an envelope that helps them infect cells. This envelope is composed of lipids and proteins from the host cell.

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How big are viruses?

Viruses can range in size from 10 to 300 nanometers. This means they are extremely small and can only be seen with an electron microscope.

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What diseases can viruses cause?

Viruses can cause a wide range of diseases, from the common cold to more serious illnesses like HIV/AIDS and Ebola.

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What is a viral capsid?

A protective protein coat that encases the viral genome, made up of repeating subunits called capsomeres.

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What is the nucleocapsid?

The capsid and the viral nucleic acid (DNA or RNA) together.

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What is a 'naked' or nonenveloped virus?

Viruses that lack an envelope, relying solely on their capsid for protection.

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What is the viral genome?

The genetic material of a virus, which can be either DNA or RNA, and can be single-stranded or double-stranded.

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Describe the shape of a helical virus.

Coiled, tube-like shapes.

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Describe the shape of an icosahedral virus.

Many-sided, geometric shapes.

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Describe the shape of a complex virus.

Viruses with complex shapes, often a combination of helical and icosahedral structures.

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What are viral outer proteins?

Viral proteins located on the outer surface of a virus that mediate attachment to host cell receptors, induce neutralizing antibodies, and are targeted by the immune system.

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What are prions?

A type of infectious agent that consists solely of protein and lacks any genetic material (DNA or RNA).

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What is uncoating?

The process by which a virus releases its genetic material (DNA or RNA) from its protective protein coat, allowing the viral genome to replicate.

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What is assembly in viral replication?

The step in viral replication where viral components (e.g., viral proteins and nucleic acids) are assembled into complete infectious virus particles.

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What is viral replication?

The process by which a virus enters a host cell and replicates its genetic material, leading to the production of new viral particles.

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What is biosynthesis in viral replication?

The stage in viral replication where viral components (e.g., viral proteins and nucleic acids) are synthesized, resulting in the production of new viral particles.

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What is attachment in viral replication?

The step in viral replication where the virus attaches to the surface of a host cell via its surface proteins or spikes.

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Epstein-Barr Virus

A virus that causes infectious mononucleosis, also known as the "kissing disease". It spreads through saliva and can remain dormant in the body for life.

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Coronaviruses

A group of viruses that cause a range of illnesses in humans, including common colds, SARS, MERS, and COVID-19.

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Infectious mononucleosis

A respiratory illness caused by the Epstein-Barr virus, often characterized by fever, sore throat, and swollen lymph nodes.

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Influenza A

A type of influenza virus that can cause pandemics and infect humans, animals, and birds.

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Influenza B

A type of influenza virus that primarily infects humans and seals.

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Influenza C

A type of influenza virus that infects humans and pigs.

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MERS

A respiratory illness caused by the Middle East Respiratory Syndrome coronavirus (MERS-CoV).

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COVID-19

The first major outbreak of coronaviruses in the 21st century to become a pandemic. It can cause respiratory illness and is highly contagious.

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What is the first step in the viral life cycle?

A viral glycoprotein binds to a receptor on the surface of a host cell, allowing the virus to attach.

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What is the second step in the viral life cycle?

This is the process by which the virus enters the host cell. It can occur through fusion of the viral envelope with the host cell membrane, or via endocytosis, where the virus is taken into a vesicle.

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What is the process of uncoating in the viral life cycle?

Once inside the host cell, the virus releases its genetic material (DNA or RNA).

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How does a virus replicate its genome?

Using the host cell's machinery, the virus replicates its genetic material. This usually results in the production of new viral proteins and copies of the viral genome.

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What happens during the assembly stage of the viral life cycle?

Newly synthesized viral proteins and nucleic acid assemble into new viral particles, known as virions.

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How are new viruses released from the host cell?

New viruses are released from the host cell. This can happen through budding, where viruses are released from the cell membrane and acquire an envelope, or through cell lysis, where the host cell bursts open releasing the virions

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What is the role of the viral envelope in the life cycle?

Enveloped viruses acquire their envelope from the host cell membrane during budding. This envelope contains proteins that can help the virus attach to and enter new cells

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What is cell lysis?

This is a type of viral release caused by a non-enveloped virus. The virus attacks the cell membrane or peptidoglycan of the host cell causing it to burst, releasing the virions.

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What are the typical symptoms of MERS-CoV infection?

Symptoms of MERS-CoV infection typically include fever, cough, shortness of breath, and sometimes gastrointestinal issues like diarrhea and nausea/vomiting. Complications can include pneumonia and kidney failure.

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What is the incubation period for MERS-CoV?

The incubation period for MERS-CoV is between 2 and 14 days. This means that the time between exposure to the virus and the onset of symptoms can vary.

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Who is at higher risk of severe MERS-CoV infection?

Individuals with pre-existing medical conditions, such as diabetes, cancer, and chronic lung, heart, or kidney diseases, are more vulnerable to becoming infected with MERS-CoV or experiencing a severe case.

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What do live vaccines contain?

Live vaccines contain weakened forms of the virus, which don't cause disease but trigger immunity. However, they can be risky for people with weak immune systems.

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What do killed vaccines contain?

Killed vaccines contain killed, but previously virulent, micro-organisms. These organisms have been inactivated using methods like chemicals, heat, radiation, or antibiotics.

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What do subunit vaccines use?

Subunit vaccines use only specific parts of the virus, like the capsid proteins, to stimulate the immune system. These vaccines are produced using biotechnology techniques.

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How do antiviral drugs work?

Antiviral drugs are medications that suppress the replication of viruses, blocking the virus' ability to multiply inside host cells.

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Why are antiviral drugs difficult to develop?

Antiviral drugs are challenging to develop and use because viruses rely on host cells to reproduce. This means targeting the virus without harming the host cell is crucial.

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Study Notes

Virology Lecture Notes

  • Virology is the study of viruses
  • Viruses were discovered in the 1800s, recognized as something smaller than bacteria that could cause disease
  • Electron microscopes and x-ray crystallography made it possible to see viruses in the 1930s, and the first photographs were taken in 1940
  • Objectives of the lecture include general characteristics, structure and symmetry, classification, and replication steps of viruses

Viral Characteristics

  • Acellular particles
  • Composed of an internal core, protein coat, and in some cases, a lipoprotein membrane (envelope)
  • Obligate intracellular parasites (need a host cell to reproduce)
  • Lack an ATP generating system
  • Lack ribosomes or protein synthesis mechanisms

Viral Structure

  • Viruses contain genetic material (DNA or RNA) enclosed in a protein coat called a capsid
  • The capsid is made up of subunits called capsomeres and provides the virus its shape and size. It protects the viral nucleic acid and aids in cell entry
  • Some viruses have a lipid bilayer membrane called an envelope, derived from the host cell membrane

Viral Genome

  • Viruses have either DNA or RNA genomes
  • Viral nucleic acid can be linear or circular
  • Some can be single-stranded or double-stranded

Viral Classification

  • Viruses are characterized by their genetic material (DNA or RNA), shape of the capsid, number of capsomeres, size of the capsid, presence or absence of an envelope, type of host, type of disease, target cells and immunological properties

Viral Replication

  • Attachment - Virus binds to a host cell receptor
  • Penetration - Virus enters the host cell
  • Uncoating - Release of viral genome from its protective capsid
  • Synthesis of viral components - Virus uses the host cell to synthesize mRNA, viral proteins and nucleic acids
  • Assembly - Nucleic acid and viral proteins assemble to form new viruses
  • Release - New viruses are released from the host cell (budding for enveloped viruses, cell lysis for non-enveloped viruses)

Atypical Virus-like Agents

  • Viroids: Naked ssRNA, requiring host cell DNA-dependent RNA polymerase to replicate; plant pathogens
  • Prions: Entirely composed of proteins, causing fatal neurological diseases in animals (e.g., Mad cow disease)

Viral Proteins

  • Outer viral proteins mediate attachment to host receptors, induce neutralizing antibodies, and are targets of antibodies
  • Internal viral proteins include structural proteins (capsid proteins in enveloped viruses), non-structural proteins (enzymes), certain ssRNA viruses with transcriptase (RNA dependent RNA polymerase) inside the virions, and retroviruses and HBV with reverse transcriptase

Viral Infections

  • Include various types: encephalitis, meningitis, common cold, gingivostomatitis, cardiovascular, hepatitis, skin, sexually transmitted diseases, etc.
  • The outcome of viral infection can be cytopathic, latent, or transformational

Outcomes of Viral Infections

  • Lytic infection: Host cell dies at the end of the virus replication cycle (e.g., influenza and polio)
  • Persistent infection: Host cell remains alive and continues to produce progeny virions (e.g., hepatitis B)
  • Latent infection: The virus enters a latent state, and the host cell remains alive, virus activity becoming dormant until triggered and the virus replicates (e.g., HIV and herpes infections)
  • Transformation Infection: Infected host cells are transformed by the virus (carrying oncogenes), potentially leading to cancer (e.g., some herpesviruses.)

Specific Viruses

  • Herpesviruses: Can cause fever blisters, genital herpes, latent infections (a-herpes, b-herpes, Y-herpes)
  • Influenza: A common viral respiratory infection, varied strains lead to different pandemics and range of infections.
  • Coronavirus (MERS-CoV): Identified in Saudi Arabia in 2012; transmitted via air and close contact, causing severe acute respiratory illness; no vaccine.
  • HIV: An enveloped virus causing AIDS.
  • CMV (cytomegalovirus): A common infection that can be asymptomatic or cause mononucleosis-like symptoms.

Prevention and Treatment for Viral Infection

  • Vaccines: Used to prevent viral infections (live/attenuated, inactivated/killed, subunit)
  • Antiviral drugs: Inhibit viral replication or proteins involved in replication in the host cell (they work by inhibiting viral replication inside cells, attachment, uncoating, and Inhibit DNA/RNA synthesis)

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Virology Lecture Notes (CLS212) PDF

Description

Test your knowledge on the fundamental concepts of virology with this quiz. Topics include viral structures, replication cycles, and distinct virus classifications. Perfect for students studying virology or biology.

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