Recent

  • Show all results for ""

🎧 New: AI-Generated Podcasts Turn your study notes into engaging audio conversations. Learn more

Animal Models in Bacterial Infection Research
40 Questions
0 Views

Animal Models in Bacterial Infection Research

Created by
@LighterBlueLaceAgate803

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the role of the Lewis b antigen in H.pylori infections?

  • It enhances the immune response against H.pylori.
  • It serves as a receptor for attachment of H.pylori to gastric cells. (correct)
  • It protects gastric cells from bacterial adhesion.
  • It is a type of antibiotic used in treatment.

    • What is a primary characteristic of gnotobiotic animals?

  • They require a high level of standard care for maintenance.
  • They are selectively bred for resistance to pathogens.
  • They have fully developed mucosa-associated-lymphoid tissue.
  • They are raised without any exposure to microbes. (correct)

    • Which statement best describes specific-pathogen-free (SPF) animals?

  • They have never been exposed to any microbes.
  • They are living under constant sterile conditions.
  • They possess immunity from prior infections by all pathogens.
  • They are only free of a particular pathogen while exposed to others. (correct)

    • What is a significant limitation of using gnotobiotic animals in research?

    <p>They cannot develop immunity to pathogens.</p> Signup and view all the answers

    Why is it essential to fully characterize bacterial strains before conducting animal experiments?

    <p>To accurately interpret the host's response to the pathogen.</p> Signup and view all the answers

    What ethical consideration must be made when conducting experiments with animal models?

    <p>There must be compelling reasons for infection experiments with animals.</p> Signup and view all the answers

    What could be a reason for the cost of maintaining gnotobiotic animals?

    <p>They need sterile environments that are expensive to maintain.</p> Signup and view all the answers

    What primary insight have gnotobiotic animals provided in the study of microbes?

    <p>They offer insights into the nature of commensalism and microbial interactions.</p> Signup and view all the answers

    What does a lower LD50 value indicate about a bacterium?

    <p>The bacterium is more infectious.</p> Signup and view all the answers

    Why might LD50 and ID50 values lack sensitivity according to the limitations discussed?

    <p>They do not account for mutations in virulence genes.</p> Signup and view all the answers

    In comparing the infectious nature of two bacteria, which factor must be considered when using ID50 values?

    <p>The cumulative effect of colonization.</p> Signup and view all the answers

    What is a major limitation of using LD50 and ID50 values across different diseases?

    <p>They cannot effectively compare different diseases.</p> Signup and view all the answers

    What is the ID50 value of the bacterium that causes cholera in humans?

    <p>10,000 bacteria.</p> Signup and view all the answers

    Which bacterium is considered more infectious based on the ID50 values provided?

    <p>Bacterium A with ID50 = 102</p> Signup and view all the answers

    What is the typical ID50 value range for bacterial dysentery?

    <p>10 to 20 bacteria.</p> Signup and view all the answers

    What does having a high ID50 value suggest about a bacterium's ability to cause disease?

    <p>It is less infectious and may require more organisms to cause disease.</p> Signup and view all the answers

    What is necessary to achieve a polarized monolayer in tissue culture cells?

    <p>Providing an extracellular-matrix substitute and hormones</p> Signup and view all the answers

    What discrepancy may arise when comparing tissue culture cells to in vivo tissue cells?

    <p>Surface proteins are typically misdistributed in culture</p> Signup and view all the answers

    What is often overlooked in the evaluation of polarized monolayers in tissue culture?

    <p>The expression and distribution of surface molecules</p> Signup and view all the answers

    How can cultured cell lines be effectively utilized despite their limitations?

    <p>By designing experiments that can be tested in intact animals</p> Signup and view all the answers

    What is a common mistake made when interpreting results from tissue culture studies?

    <p>Assuming similarities between cultured cells and in vivo environments</p> Signup and view all the answers

    What specific characteristic is observed in nonconfluent tissue culture cells?

    <p>Lack of polarity</p> Signup and view all the answers

    What is the role of extracellular matrix substitutes in tissue culture?

    <p>To aid in the formation of a polarized monolayer</p> Signup and view all the answers

    Why is it important to confirm the characteristics of polarized cell monolayers?

    <p>To validate their similarity to in vivo conditions</p> Signup and view all the answers

    What role does gentamicin play in the invasion assay?

    <p>It selectively kills extracellular bacteria.</p> Signup and view all the answers

    What is the primary measurement obtained from the invasion frequency calculation?

    <p>The ratio of gentamicin-resistant CFU to cell-associated CFU.</p> Signup and view all the answers

    What does a lack of colonies form on agar plates from the second and third sets of wells indicate?

    <p>The bacterial strain is defective in adhesion factors.</p> Signup and view all the answers

    In the context of the gentamicin protection assay, what does the presence of colonies only on plates from the second set of wells suggest?

    <p>Bacteria successfully adhered but did not invade.</p> Signup and view all the answers

    Which of the following is NOT a step in the invasion assay procedure?

    <p>Centrifuging all samples before plating.</p> Signup and view all the answers

    What can be inferred if there is a significant variation in the ratio of gentamicin-resistant CFU to the total CFU?

    <p>The adherence frequency varies for different bacterial strains.</p> Signup and view all the answers

    In which situation would centrifugation steps be necessary during the invasion assay?

    <p>When mammalian cells are cultured in suspension.</p> Signup and view all the answers

    What defines a bacterial strain as a mutant in the context of this assay?

    <p>It is capable of adhering but cannot survive within mammalian cells.</p> Signup and view all the answers

    What is one of the main advantages of using organ cultures over tissue culture cells?

    <p>Presence of multiple cell types including immune cells</p> Signup and view all the answers

    Why might organ cultures be difficult for long-term experiments?

    <p>They can deteriorate within hours or days</p> Signup and view all the answers

    What specific example of organ culture research was mentioned?

    <p>Developing models with C. jejuni using gastrointestinal tissue</p> Signup and view all the answers

    Why have researchers turned to developing artificial organ cultures?

    <p>Due to limited supply of organ cultures from donors</p> Signup and view all the answers

    What process occurs in making artificial skin equivalents?

    <p>Using human foreskin fibroblasts in a collagen matrix</p> Signup and view all the answers

    What has the popularity of cosmetic surgery provided for scientific research?

    <p>Access to large amounts of skin tissue</p> Signup and view all the answers

    What has caused a decrease in the availability of fallopian tube and uterine tissues?

    <p>A trend away from complete hysterectomies</p> Signup and view all the answers

    What is the outcome of keratinocyte seeding in artificial skin development?

    <p>Covering the surface and forming skin layers</p> Signup and view all the answers

    Study Notes

    Animal Models in Bacterial Infection Research

    • Leb mice, carrying the human Lewis b antigen, are used to study Helicobacter pylori infections.
    • Lewis b antigen acts as a receptor for H. pylori attachment to gastric cells and mucin.
    • Germ-free animals, raised in sterile environments, lack bacteria and have underdeveloped mucosal-associated lymphoid tissue (MALT).
    • These animals are expensive to maintain and lack immunity due to prior exposure.
    • Specific-pathogen-free animals are raised in an environment free of a specific pathogen but exposed to other microbes.
    • They are useful for studying host response without pre-existing immunity.
    • Gnotobiotic animals are crucial for understanding immunity in "truly naive" animals and the nature of commensalism.

    Measuring Bacterial Infection in Animal Models

    • Ethical considerations are crucial when using animal models in research, as they involve bacterial infections.
    • Justification for animal experiments:
      • Characterize bacterial strains before conducting experiments
      • The lower the LD50 (lethal dose) or ID50 (infectious dose), the more lethal or infectious the bacterium.
    • LD50 and ID50 offer valuable measures of virulence but have limitations:
      • They lack sensitivity and may not always reflect individual virulence determinants.
      • They require a large number of animals for testing.
      • They provide a relative measure of virulence when comparing strains or mutants, but can be misleading when comparing different diseases.
    • For example, cholera has a higher ID50 than bacterial dysentery, but cholera can be fatal while dysentery is less lethal.

    Tissue Culture Models

    • Tissue culture cells can be used to study bacterial infections but have some limitations:
      • Protein distribution can differ from in vivo, as cells lack differentiated surfaces.
      • Polarization of monolayers may not accurately reflect in vivo tissue.
    • Though they have limitations, tissue culture cells are useful tools for discovering new phenomena.
    • They can generate hypotheses that can later be tested in animals.
    • Results from tissue culture cells should not be directly extrapolated to human diseases.

    Invasion Assay

    • A gentamicin protection assay is used to measure bacterial invasion.
    • Gentamicin kills extracellular bacteria and does not penetrate mammalian cells, allowing the measurement of internalized bacteria.
    • Invasion frequency is determined by comparing gentamicin-resistant CFU to cell-associated CFU.

    Interpretation of Invasion Assay

    • Bacterial mutants defective in adhesion factors will show no colonies on agar plates for the second and third sets of wells.
    • Mutants able to adhere but defective in invasion factors will produce colonies on plates from the second set but not the third.
    • Comparing adherence and invasion frequencies for wild-type and mutant bacteria helps determine the nature of the defective virulence factor.

    Organ Cultures

    • Offer a better model of natural infection than tissue culture cells as they contain multiple cell types, including immune cells.
    • They provide a more accurate representation of what occurs in vivo but can be difficult to obtain and maintain.
    • Ex vivo organ cultures using human gastrointestinal tissue are useful for studying pathogens like Campylobacter jejuni and its flagellum-mediated adherence.

    Source of Tissues and Organs

    • Skin cells for research are readily available due to cosmetic surgery.
    • Fallopian tube and uterine tissues are available from hysterectomies, but availability has decreased.
    • Obtaining tissues like liver or heart is limited.

    Artificial Organ Cultures

    • Artificial organ cultures are being developed to overcome limitations of donor-derived organ cultures.
    • Examples include artificial skin equivalents cultured from human foreskin fibroblasts and keratinocytes.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Measuring Infectivity and Virulence PDF

    Description

    Explore the role of various animal models in the study of bacterial infections, specifically focusing on Helicobacter pylori. This quiz covers the use and ethical considerations of germ-free, specific-pathogen-free, and gnotobiotic animals in research. Test your understanding of how these models contribute to our knowledge of host response and immunity.

    More Quizzes Like This

    Animal Models in Biomedical Research
    44 questions

    Animal Models in Biomedical Research

    AdorableSardonyx avatar
    AdorableSardonyx
    Atherosclerosis in Animal Models
    25 questions

    Atherosclerosis in Animal Models

    ElegantChrysanthemum avatar
    ElegantChrysanthemum
    Rabbit as an Animal Model for Research
    20 questions

    Rabbit as an Animal Model for Research

    AdventurousObsidian avatar
    AdventurousObsidian
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser