Agricultural Microbiology Course Quiz

Agricultural Microbiology Course

• Course code: MICR20010
• Lecturer: Dr. Tadhg Ó Cróinín

Remaining Lectures

• Lecture 10: Microorganisms and Disease
• Lecture 11: The Immune System
• Lecture 12: Pathogenic Bacteria
• Lecture 13: Pathogenic Fungi and Viruses
• Lecture 14: Antibiotic Resistant Microorganisms
• Lecture 15: Microbiology in the Food Industry - Fungi
• Lecture 16: Microbiology in the Food Industry - Fermentation
• Lecture 17: The Nitrogen Cycle

Immune System vs Pathogens

• An image of an immune cell interacting with a pathogen is displayed.

Immunity Concepts

• Susceptibility: Lack of resistance to a disease
• Immunity: Ability to ward off disease
• Innate immunity: Defenses against any pathogen
• Adaptive immunity: Immunity to a specific pathogen

Pathogens and the Immune System

• Pathogens: Agents that cause disease, infecting a wide range of animals, including humans
• The immune system recognizes foreign bodies and responds by producing immune cells and proteins
• All animals have innate immunity, a defense that is active immediately upon infection
  • Skin
  • Chemical secretions that trap/kill microbes
• Vertebrates also have adaptive immunity (acquired immunity).

Innate Immunity

• Innate immunity is present before any pathogen exposure
• It is effective from birth
• It involves nonspecific responses to pathogens
• Innate immunity consists of external barriers (e.g., skin) plus internal cellular and chemical defenses (e.g., mucus membranes trapping bacteria).

Adaptive Immunity

• Adaptive immunity develops after exposure to pathogens, toxins, or other foreign substances
• Adaptive immunity involves a very specific response to pathogens.
• Two main types of lymphocytes (white blood cells) are involved in adaptive immunity
  • T-cells: mature in the thymus.
  • B-cells: mature in the bone marrow.

Immune System: Microbes and Defenses

• The immune system identifies bacteria and fungi by structures on their cell walls
• Pathogens entering the mammalian body are subject to phagocytosis.
• Phagocytic cells recognize groups of pathogens via Toll-like receptors (TLRs).

Formed Elements in Blood

• Red Blood Cells: Transport oxygen (O₂) and carbon dioxide (CO₂).
• White Blood Cells:
  • Neutrophils: Phagocytosis (engulfing and destroying pathogens)
  • Eosinophils: Kill parasites
  • Monocytes: Phagocytosis (become macrophages)
  • Dendritic cells: Phagocytosis, stimulate adaptive immunity
  • Natural killer cells: Destroy target cells (viruses or cancer)
  • T cells: Cell-mediated immunity
  • B cells: Produce antibodies
  • Platelets: Blood clotting

Phagocytosis

• Process where a white blood cell engulfs a microbe
  • Different types of phagocytic cells are involved
    • Neutrophils: Engulf and destroy pathogens
    • Macrophages: Found throughout the body
    • Dendritic cells: Stimulate adaptive immunity
    • Eosinophils: Discharge destructive enzymes

Extracellular Killing by Leukocytes

• Eosinophils and Natural Killer (NK) cells are involved
  • NK cells: kill infected cells by secreting toxins onto their surface
  • NK can distinguish normal from infected cells via membrane proteins

2nd Line of Defence

• Neutrophils carry out extracellular killing in several ways
• Employ enzymes to produce oxygen and hydrogen peroxide (converted to hypochlorite)
• Produce nitric oxide (induces inflammation)
• Form neutrophil extracellular traps (NETs)
• Kill via immobilisation

Antibody Function

• Antibodies mark pathogens for destruction (opsonization)
• Antibodies bind to viral surface proteins or toxins, preventing infection of host cells (neutralization)

B Cells

• B cells can express different forms (classes) of immunoglobulins (Ig)
  • IgD: Membrane-bound
  • IgM: First soluble class
  • IgG: Second soluble class, most abundant
  • IgA/IgE: Remaining soluble classes

Active and Passive Immunization

• Active immunity can be developed naturally by memory cells forming clones in response to an infection
• Passive immunity: Antibodies are directly donated
• Vaccination, is a non-pathogenic form of a microbe or part of a microbe which elicits an immune response to an immunological memory

Vaccines

• Vaccines are harmless derivatives of pathogenic microbes that stimulate an immune response against the harmful pathogen
• Vaccines can prevent certain viral illnesses

Measles in the United States (1960-2007)

• Detailed graph showing a sharp decline in reported cases after the measles vaccine was licensed.

Vaccine Hesitancy and Effectiveness

• Graph illustrating a correlation between vaccination rates and pertussis cases.

A Recent Challenge - Covid-19 Vaccine

• Covid-19 vaccine market is worth $10bn a year.
• Much of the research into Covid-19 vaccines has been funded by governments.

Brief History of Coronavirus Discovery

• Timeline illustrating the discovery of various coronaviruses and relevant technologies/findings associated with each.

Nucleic-Acid Vaccines

• Two main types of nucleic-acid vaccines: DNA and RNA.
• Processes for delivering the genetic material into the cell are detailed
• Specific advantages and disadvantages of this type of vaccine are explained

Covid-19 Vaccine Success

• Pfizer/BioNTech vaccine is proving 90% effective in trials.
• Milestone achievement for global Covid-19 response strategy

Pathogenic Bacteria

• This lecture will focus on pathogenic bacteria and their properties.

Test your knowledge on the relationship between microorganisms and disease, as well as the immune system's mechanisms in protecting against various pathogens. This quiz covers crucial concepts from the Agricultural Microbiology course, including pathogens, immunity types, and their implications in food microbiology. Join to see how well you understand these fundamental concepts!