VMED280: Introduction to Virology

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Questions and Answers

What is a key structural feature that differentiates viruses from bacteria?

  • Viruses possess a simple structure compared to bacteria.
  • Viruses have DNA while bacteria have RNA.
  • Viruses always have a membrane structure. (correct)
  • Bacteria contain protein coats while viruses do not.

Which of the following diseases is indicative of smallpox?

  • Pock marks. (correct)
  • Lung inflammation.
  • Leg deformities.
  • Respiratory distress.

In what year were leg deformities indicative of poliomyelitis first recorded?

  • 1500 BC (correct)
  • 1000 AD
  • 500 AD
  • 2000 BC

Which of these is not considered a property of viruses?

<p>Ability to replicate independently. (C)</p> Signup and view all the answers

What is the general classification criterion for viruses?

<p>Structure and type of genetic material. (C)</p> Signup and view all the answers

What type of viral infection is characterized by ongoing viral replication with few or no symptoms?

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

Which virus is primarily associated with oncogenesis?

<p>Human papilloma virus (B)</p> Signup and view all the answers

Which method is NOT typically used in the laboratory diagnosis of viral infections?

<p>Patient history review (A)</p> Signup and view all the answers

Which characteristic is associated with latent infections?

<p>Virus remains non-replicating and may integrate its genome (B)</p> Signup and view all the answers

What viral disease does NOT typically present any apparent disease symptoms?

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

What is a mode of transmission for HIV?

<p>Direct personal contact (C)</p> Signup and view all the answers

Which of the following viruses is known for airborne spread?

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

What type of transmission involves sharing needles or blood products?

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

Which virus is NOT typically associated with vertical transmission?

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

Which of the following is a common method of virus release from an infected cell?

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

What is a feature of enteral transmission?

<p>Involves ingestion of contaminated food or water (C)</p> Signup and view all the answers

Which is an example of a virus that can be spread via fomites?

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

What types of viruses are primarily formed within a host cell during infection?

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

What is essential for a virus to enter a host cell?

<p>The outer surface of the virus (C)</p> Signup and view all the answers

How do viruses typically transmit from one host to another?

<p>In droplets or food and water (D)</p> Signup and view all the answers

What do viruses rely on to process their genetic information into new virus particles?

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

What is the role of viral enzymes during the replication process?

<p>To facilitate the replication of viral RNA or DNA (A)</p> Signup and view all the answers

What is one requirement for a virus to survive in the outside world?

<p>A viable outer surface structure (C)</p> Signup and view all the answers

Which of the following is an example of a naked DNA virus?

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

What is a helical RNA virus from the provided list?

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

Which route is most commonly associated with viral entry into the body?

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

Which of the following viruses is transmitted through food or water?

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

What type of virus is Coxsackie virus classified as?

<p>Naked RNA virus (C)</p> Signup and view all the answers

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Study Notes

Introduction to Virology

  • Viruses differ from bacteria in structure, classification, and properties.
  • Viral diseases have been recognized for centuries, with evidence of smallpox around 1500 BC and poliomyelitis-related leg deformities.

Virus Structure and Classification

  • Viruses can be categorized based on their genetic material: DNA or RNA.
  • DNA viruses:
    • Examples include Papillomavirus (naked), Herpes viruses (enveloped), and Pox viruses (complex).
  • RNA viruses:
    • Examples include Picornaviruses (naked), Influenza (enveloped), and Retroviruses (enveloped).

Modes of Virus Entry

  • Common routes of viral entry include:
    • Inhaled droplets (e.g., rhinovirus).
    • Ingestion through contaminated food or water (e.g., hepatitis A).
    • Direct transfer from infected hosts (e.g., HIV).
    • Arthropod bites (e.g., yellow fever).

Infection Acquisition

  • Transmission methods:
    • Direct contact (e.g., herpes viruses, HIV).
    • Airborne spread (e.g., chickenpox).
    • Parenteral exposure (e.g., HIV, hepatitis B and C).
    • Contact with fomites (e.g., enteroviruses).
    • Vectors (e.g., West Nile virus).
    • Vertical transmission (e.g., HIV, rubella).
    • Foodborne routes (e.g., hepatitis A).

Viral Replication Process

  • A single host cell can produce thousands of viral particles.
  • Enveloped RNA viruses (e.g., Influenza A) replicate by budding through the host cell membrane.

Consequences of Virus-Cell Interaction

  • Viral infections can lead to various outcomes:
    • Lysis of host cells, as seen in cold sores and chickenpox.
    • Latent infections with non-replicating viruses (e.g., herpes viruses).
    • Persistent infections with ongoing viral replication, resulting in tissue injury (e.g., hepatitis B and C, HIV).
    • Induction of oncogenesis, linking certain viruses to cancer (e.g., human papillomavirus, EBV).
    • Asymptomatic infections may occur (e.g., hepatitis G).

Diagnosis of Viral Infections

  • Diagnosis relies on clinical features and laboratory tests, including:
    • Histology and cytology techniques.
    • Electron microscopy for direct examination.
    • Detection of viral antigens in tissues and serum.
    • Antibody testing (IgG, IgM detection).
    • Virus isolation and amplification of viral DNA or RNA.

Important Virus Characteristics

  • Viruses depend on host cells for replication and require cellular machinery to process genetic information.
  • Virus envelopes or capsids play critical roles in host cell attachment and entry.
  • Transmission typically occurs through respiratory droplets or contaminated food/water.

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