MicrobiologyLesson 2 of 3 in the course Microbial Mechanisms of Pathogenicity

Pathogen Virulence: Adhesion, Invasion, Immune Evasion, and Viral Change

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Virulence factors are pathogen features that help microbes cause disease. This lesson introduces how virulence relates to disease severity and how adhesins enable pathogens to attach to host cells, an early step in pathogenesis.

A pathogen’s virulence is its relative ability to cause disease or produce severe disease. Virulence factors contribute to particular steps in pathogenesis, including attachment, invasion, survival in the host, and damage to tissues. The presence and activity of these factors help explain why different pathogens, or different strains of one pathogen, can cause diseases of different severity.

All flashcards

What is virulence?
A pathogen’s relative ability to cause disease or produce severe disease.
What is an adhesin?
A protein or glycoprotein on a pathogen’s surface that binds a host-cell receptor.
What does molecular Koch’s postulates predict when a virulence gene is inactivated?
If the gene contributes to virulence, inactivating it should diminish the pathogen’s ability to cause disease.
How does ETEC attach to intestinal epithelial cells?
Its type 1 fimbriae carry adhesins that bind mannose glycans on intestinal epithelial cells.
What causes antigenic shift in influenza viruses?
Reassortment of gene segments, which can produce major changes in viral surface proteins.

Quiz questions

  1. What does listeriolysin O (LLO) enable Listeria monocytogenes to do after entering a host cell?Answer: Escape from the vacuole into the host-cell cytoplasm.
  2. Which statement defines septicemia?Answer: Bacteria are present and multiplying in the blood.
  3. What is the endotoxin of gram-negative bacteria?Answer: Lipid A, a component of lipopolysaccharide in the outer membrane.
  4. How does diphtheria toxin damage host cells?Answer: It interferes with EF-2 and thereby blocks protein synthesis.
  5. What does viral tropism describe?Answer: A virus’s preference for particular cells, tissues, or organs.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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