Virology Quiz on Viral Genomes and Classification
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Questions and Answers

Which of the following viruses are classified as members of the Parvoviridae family?

  • Human Papilloma virus (HPV)
  • Hepatitis C virus
  • Parvovirus B19 (correct)
  • Adenovirus1

Which viral family is known for causing hemorrhagic fever?

  • Bunyaviridae (correct)
  • Picornaviridae
  • Rhabdoviridae
  • Orthomyxoviridae

Which type of viral genome can be classified as 'gapped'?

  • Circular DNA with a gap (correct)
  • Linear DNA
  • Circular DNA
  • Segmented RNA

What is the key characteristic of a 'single-stranded ambisense (+/-)' RNA genome?

<p>It contains both positive and negative strands linked together with a loop (A)</p> Signup and view all the answers

Which of the following viruses is NOT classified as a DNA virus based on the provided information?

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

What is the difference between ssRNA(+) and ssRNA(-) viral genomes?

<p>ssRNA(+) genomes can directly translate into proteins, ssRNA(-) needs to be transcribed first (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of viral genomes?

<p>Viral genomes always encode for all the proteins needed for replication (A)</p> Signup and view all the answers

Which of the following viruses is known as the agent of smallpox?

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

What is the primary purpose of the molecular technique based on the detection of viral antigens?

<p>To confirm a diagnosis in immunocompromised patients (A)</p> Signup and view all the answers

Which of the following is NOT a potential problem associated with the rapid diagnosis technique based on viral antigens?

<p>Quick availability of results (A)</p> Signup and view all the answers

What is a critical factor to consider for an accurate diagnosis when suspecting a respiratory infection?

<p>Sample collection method (D)</p> Signup and view all the answers

Which immunological technique is mentioned as a method to detect specific viral antigens?

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

What is a notable disadvantage of using rapid antigen detection tests?

<p>It has low sensitivity compared to traditional methods. (B)</p> Signup and view all the answers

In the context of viral infections, which patient group is primarily targeted for the rapid diagnosis based on detection of viral antigens?

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

What type of samples are primarily used for the detection of respiratory and gastrointestinal viruses?

<p>Samples from specific locations (B)</p> Signup and view all the answers

Why is it particularly important to have good specimens when performing viral antigen tests?

<p>To achieve better accuracy in diagnosis. (B)</p> Signup and view all the answers

What is the main enzymatic function of reverse transcriptase in retroviruses?

<p>To convert RNA into cDNA (C)</p> Signup and view all the answers

Which retrovirus was discovered by Gallo in 1981?

<p>HTLV-III (A)</p> Signup and view all the answers

Which of the following statements about retroviruses is correct?

<p>They are enveloped viruses with a single-stranded RNA. (B)</p> Signup and view all the answers

What did Bishop and Varmus contribute to the understanding of retroviruses?

<p>They elucidated the origins of retroviral oncogenes. (B)</p> Signup and view all the answers

Which viruses were initially dismissed by the scientific community despite their later importance?

<p>Avian leukosis and Rous sarcoma viruses (B)</p> Signup and view all the answers

What significant change did the discovery of reverse transcriptase contribute to molecular biology?

<p>It demonstrated that RNA can serve as a template for DNA synthesis. (A)</p> Signup and view all the answers

What role did Ellerman and Bang play in the study of viruses and cancer?

<p>They established the viral cause of leukemia in chickens. (C)</p> Signup and view all the answers

When was the first case of AIDS reported and by whom?

<p>In 1981 by Antony Fauci (D)</p> Signup and view all the answers

What is the main role of IgGs in relation to viruses?

<p>They block the interaction of receptors to anti-receptors. (C)</p> Signup and view all the answers

What does seropositivity indicate?

<p>Presence of antibodies against various viruses. (D)</p> Signup and view all the answers

Which virus typically offers lifelong immunity?

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

What is primarily detected in direct virologic diagnosis?

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

What is seroconversion?

<p>The appearance of IgMs and/or IgGs in a second sample. (A)</p> Signup and view all the answers

What characteristic is true of IgMs during a primary viral infection?

<p>They decrease after one month. (A)</p> Signup and view all the answers

Which method is considered the most current for direct viral detection?

<p>Nucleic acid detection. (C)</p> Signup and view all the answers

Which antibodies usually rise in levels after the decline of IgMs?

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

What characterizes acute infections followed by viral clearance?

<p>They resolve quickly within 1-2 weeks. (A)</p> Signup and view all the answers

What is an essential component of the immune response to viral infections like influenza?

<p>A protective long-term immune response. (A)</p> Signup and view all the answers

What usually occurs after the resolution of an acute viral infection?

<p>A new infection can occur upon contact with the virus. (D)</p> Signup and view all the answers

What is necessary for achieving high levels of protection against viruses like influenza?

<p>Regular annual vaccinations. (D)</p> Signup and view all the answers

Why do symptoms recur with new strains of the influenza virus?

<p>The body does not recognize the new strain. (A)</p> Signup and view all the answers

What is true of the immune response to respiratory viruses?

<p>The immune response can be temporary or long-lasting. (D)</p> Signup and view all the answers

What typically begins the cycle of infection with viruses like influenza?

<p>Exposure to a new viral strain. (B)</p> Signup and view all the answers

Which of the following best describes the overall nature of acute viral infections?

<p>They usually resolve but may lead to re-infection. (C)</p> Signup and view all the answers

What is the primary characteristic of oncoretroviruses?

<p>They produce or activate oncoproteins that alter the cell cycle. (C)</p> Signup and view all the answers

What distinguishes lentiviruses from other retroviruses?

<p>They can persist in a clinically latent state for a long time. (C)</p> Signup and view all the answers

Which type of HIV is considered more pathogenic?

<p>HIV-1, as it is responsible for most AIDS cases. (B)</p> Signup and view all the answers

What is the role of antiretroviral therapy (ART) in HIV treatment?

<p>It halts viral replication, delaying disease progression. (B)</p> Signup and view all the answers

Which family of viruses are primarily associated with immune system disorders and tumors in humans?

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

What does the term 'oncogenic' refer to?

<p>Viruses that can lead to the formation of tumors. (A)</p> Signup and view all the answers

Which retrovirus subfamily is NOT associated with tumors in humans?

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

What structural feature is commonly observed in retroviruses using electron microscopy?

<p>A core with a capsid and an outer envelope. (B)</p> Signup and view all the answers

Flashcards

Viral Genome Structures

Viral genomes can be arranged in different ways, including linear, circular, segmented, and gapped structures.

ssRNA(+) virus

A single-stranded RNA virus whose genome directly serves as mRNA, allowing for immediate protein synthesis.

ssRNA(-) virus

A single-stranded RNA virus whose genome is complementary to mRNA and needs to be transcribed into a positive strand before protein synthesis can occur.

Ambisense RNA virus

A single-stranded RNA virus that has both positive and negative RNA segments in its genome, linked by a loop.

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Circular dsDNA

A complete double-stranded DNA molecule with both ends covalently linked.

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Gapped DNA virus

A viral DNA genome that is partially double-stranded and circular, but with a gap that needs to be filled before replication can occur.

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Cross-linked dsDNA

A viral DNA molecule that is partially double-stranded and has both ends covalently linked.

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DNA-RNA Hybrid

A type of viral DNA genome that is covalently attached to a RNA molecule.

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Acute viral infection with clearance

An infection where the virus is eliminated from the body by the immune system, leading to a short-term illness.

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Immune response

The body's response to infection, involving cells that target and destroy viruses.

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Antibodies

Specific proteins produced by the immune system to fight off viruses and other pathogens.

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Vaccination

The process of introducing weakened or dead virus particles to the body to stimulate antibody production and provide immunity.

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Vaccination and influenza

In the case of influenza, vaccination helps maintain high levels of antibodies to protect against different strains.

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Viral strain variation

Some viruses, like influenza, can evolve and change, creating new strains.

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Reinfection

Contact with a new or different influenza virus can lead to reinfection.

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Repeated infection cycles

Repeated exposure to the same or different viruses can lead to repeated cycles of infection and recovery.

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Neutralizing Antibodies (IgGs)

Antibodies that can block the interaction between a virus and its host cell receptor, preventing infection. They are often produced by vaccines to protect against viruses.

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Direct Virologic Diagnosis

A type of laboratory test used to detect the presence of viruses, typically through identifying viral antigens or nucleic acids directly in a sample.

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Indirect Virologic Diagnosis

A type of laboratory test used to detect the presence of antibodies against a specific virus, indicating past exposure or infection.

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Seropositivity

A state where a person's blood contains antibodies against a specific virus, indicating previous exposure to that virus. This can be a sign of immunity, but not necessarily a guarantee of protection.

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Seroconversion

The process of an immune response in which antibodies switch from the IgM type to IgG type, indicating a more sustained and specific immune response to a virus. This typically occurs a few weeks after initial infection.

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IgM Antibodies

The type of antibody primarily produced early in a viral infection, often disappearing after a few weeks.

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IgG Antibodies

The type of antibody that typically rises after IgM antibodies decline and can last for a longer period of time, often providing sustained protection against reinfection.

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Serology

A laboratory test that analyzes blood serum for the presence of specific antibodies. This can help diagnose past or current infections, monitor immune responses, and assess levels of immunity.

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Rapid Antigen Detection for Immunocompromised Patients

Rapid diagnosis based on detecting viral antigens is particularly important for immunocompromised patients who may not mount a robust immune response.

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Molecular Technique in Rapid Antigen Detection

Rapid antigen detection utilizes molecular techniques to identify specific viral antigens in patient samples.

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Applications of Rapid Antigen Detection

Rapid antigen detection is highly useful for identifying respiratory and gastrointestinal viruses, as it allows for quick and accurate diagnosis.

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Immunofluorescence in Rapid Antigen Detection

Immunofluorescence is a common technique used in rapid antigen detection to identify specific antigens.

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Sensitivity of Rapid Antigen Detection

Rapid antigen detection can be less sensitive than cell culture, with a sensitivity as low as 20%.

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Specificity of Rapid Antigen Detection

Rapid antigen detection can have poor specificity, leading to potential false positive results.

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Specimen Quality in Rapid Antigen Detection

Rapid antigen detection requires good quality specimens for accurate results.

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Time and Cost of Rapid Antigen Detection

Rapid antigen detection procedures can be tedious and time-consuming, leading to increased costs.

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Retroviridae

A family of enveloped (+) sense ssRNA viruses that replicate through a DNA intermediate using reverse transcriptase.

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Oncovirus

A type of retrovirus known to cause cancer.

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Reverse Transcriptase

The enzyme used by retroviruses to create a DNA copy from their RNA genome.

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Integration

The process where the viral DNA integrates into the host's genome.

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Subverting the Central Dogma

The central dogma of molecular biology states that genetic information flows from DNA to RNA to protein. Retroviruses subvert this dogma by transcribing RNA into DNA.

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Retroviral Oncogenes

Genes originating from cellular DNA that are captured by retroviruses. They can contribute to cancer development.

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Acquired Immunodeficiency Syndrome (AIDS)

A condition caused by retroviruses, primarily HIV, causing a severe immune deficiency.

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Human Immunodeficiency Virus (HIV)

The retrovirus responsible for causing AIDS.

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Lentiviruses

These viruses are known for their slow progression and ability to persist in the body for extended periods, even in a clinically latent state, before causing symptoms.

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Oncoretroviruses

These viruses are directly associated with the development of tumors in various animals. While they don't directly kill cells, they produce or activate proteins that alter the cell cycle, leading to uncontrolled growth.

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Lentivirus (Slow Virus)

A type of retrovirus that replicates slowly and can remain dormant in the body for long periods, eventually causing significant immune suppression.

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HIV-1

A type of retrovirus that is particularly common in humans and is responsible for the majority of AIDS cases worldwide.

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Oncoretroviruses

Responsible for causing a wide range of cancers in diverse animal species including leukemias, lymphomas, and sarcomas. These viruses are not known to kill cells directly, but they produce or activate proteins that can lead to uncontrolled growth.

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HIV-2

A less pathogenic type of HIV that is mainly found in less developed countries. It is also found in West Africa.

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Lentivirus

A member of the Retroviridae family that can persist in the body for many years before causing symptoms. It is known for its ability to integrate its genetic material into the host's DNA, leading to long-term infection.

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Study Notes

Medical Virology

  • Viruses are ubiquitous, infecting all organisms from bacteria to humans.
  • Viruses carry viral genomes as part of genetic material.
  • Viruses can have interactions with organs that can be beneficial.
  • Viruses are responsible for many human diseases.
  • Viruses interact with the host, and after infection, can persist for a lifetime.
  • Viruses are abundant in marine environments, killing up to 40% of marine microbes daily, converting them into phytoplankton.

The Virome

  • Virtually all parts of the body are susceptible to viral infection.
  • Viruses can persist in either an active or latent form within the host.
  • Asymptomatic infections are common in immunocompetent hosts.
  • Symptomatic infections are more common in immunocompromised hosts.
  • A vast majority of viruses have no significant effect on human health.

History of Virology

  • Molecular evolution places some viruses among dinosaurs.
  • Viral study started in the 19th century.

First Vaccine and Variolation

  • Variolation, first method for smallpox vaccination, involved inoculation of pus from a smallpox pustule into healthy individuals.
  • This method developed specific antibodies to prevent and contrast the infection, demonstrating the effectiveness of introducing small particles to counteract large diseases.

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Description

Test your knowledge on virology with this quiz covering various viral families, genome types, and diagnostic techniques. Explore key concepts related to viruses such as Parvoviridae, smallpox, and methods for detecting viral antigens. Challenge yourself and see how well you understand the intricacies of viral classification and characteristics.

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