Host Microbe Interactions Flashcards
Do important public health diseases always cause deaths?
No.
What is disease spread and mortality rate tied with?
Social policy, social structure, and public health infrastructure.
What was disease explained by historically?
It was explained by the 4 humours, poor air, or divine/magical intervention.
What led to the ‘Germ Revolution’?
Infectious disease, alongside brewing and wine-making.
What 19th century technological and conceptual developments resulted in the acceptance of ‘Germ Theory’?
- disproving spontaneous generation
- improved microscopy
- culturing of bacteria in the laboratory
- animal models of infection.
What happened from 1880 to 1900?
There was a revolutionary change in the understanding of the world of infectious disease.
What did the acceptance of germ theory provide?
A universal approach to understanding and combatting infectious diseases.
What are the highly effective innovations introduced from 1880-1900?
- antiseptic surgery
- rationally devised vaccines
- targeted public health interventions
- antimicrobial agents.
What does viewing infectious diseases as a ‘war’ do?
It disables the understanding of them as they are a biological process.
What strain and when was it isolated that is now a major model system?
E.coli K12 was isolated in 1922.
What was the Griffith experiment in 1928?
It was an investigation of pneumococcal infection of mice which led to identifying DNA as the hereditary material. It involved rough antivirulent and smooth virulent pneeumococci.
What happened in the age of the gene?
The study of microbes became fundamental to biology.
What did the Griffith experiment find?
It led to the understanding of the importance of carbohydrates in protecting the bacteria against the immune system and encoding genetic material.
What led to the age of the genome?
Nucleotide sequencing.
What did animal infection models lead to the discovery of?
The immune system, cellular immunity, and humoral immunity.
What did the discovery of the immune system lead to?
Serum therapy, vaccines and the discovery of autoimmunity.
What is it important to always view disease as?
A biological process.
Why is it important to do microbe research in the sea?
- because the greatest diversity is in the sea
- biology started in the sea
- there are coral holobionts where viruses promote horizontal gene transfer
- it is where the evolution of the immune system would have started.
What is an important thing to understand about infection?
That it is inevitable and necessary.
Why is diet a major means of animals gaining microbes?
Because the soil contains a highly diverse microbiome which is taken up by the plants that are then eaten by animals.
What are the advantages of molecular genetic approaches?
- they enable uncultured and uncultivatable organisms to be studied
- they are scalable and cost-effecive
- they can be quantitative or at least semi-quantitiative
- they are potentially comprehensive.
What are risk factors for disease?
- breathing
- eating
- insects
- having sex.
What are formites?
They are contaminated surfaces.
How do aerosols work in transmission?
They can go within one meter and beyond, and they can be inhaled and are floating in the air for hours. They can be <5 micrometers, or 5-100 micrometers.
How do droplets work in transmission?
They can travel less than 1m and fall to the ground in under 5 seconds. They can’t normally be inhaled and they are normally over 100 micrometers.
What are the physiochemical properties of virus-laden aerosols?
- size
- viral load
- infectivity
- chemical components
- pH value
- electrical charge
- air/liquid interfacial properties.
What is the deposition efficiency of aerosols at different regions a function of?
IT is a function of aerosol diameter.
What is important in preventing faecal-oral transmission?
Effective sanitation and access to clean water.
What is the main challenge faced by pathogens when they want to use a vector like an insect?
They have to be able to survive in both the insect and the human/infecting host.
What are the early stages of an pathogen infection?
The pathogen must penetrate the mucous layer, and then to further penetrate into the host, it must move between cells or survive phagocytosis. After crossing the membrane, the pathogen grows intracellularly or intracellularly.
What are some examples of host defences and how do they happen?
- Creating a hostile environment, through environmental properties, nutrient deprevation, or using defence peptides
- Identification of the pathogen, so using molecular discrimination to distinguish self from non-self
- Killing of the pathogen, so cellular mechanisms for clearing pathogens.
What is an overview of innate immunity?
It is the identification of non-self molecules and it happens through PAMPS. There are a limited number of these patterns as they are all recptors on all phagocytes, they are always on and they are fast and resource cheap.
What does PAMPS stand for?
Pathogen Assisted Molecular Patterns.
What is an overview of adaptive immunity?
It is specific identification of cells. They happen through antibodies and T-cell receptors with modifiable receptors. There are a very large number of these cells but one receptor per lymphocyte that needs to be primed. It is slow and highly resource intensive.
What are the stages of phagocyte encounters?
- Binding
- Engulfment
- Phagosome formation
- Lysosome fusion
- Membrane disruption/fusion.
What does systematic spread happen via?
- lymphatic systems
- the blood stream
- cerebrospinal fluid to the brain
- the nervous system.
How can the immune response be evaded?
- avoiding it
- evading it
- attacking it.
What are some immune evasion mechanisms?
- secreted toxins or modulators
- modulators on the pathogen surface
- hide from immune surveillance
- antigenic hypervariability
- subvert or kill immune cells/phagocytes
- block acquired immunity
- inhibit the complement
- inhibit cytokines/interferon complement
- modulate apoptosis/chemokines
- interfere with TLRs
- block antimicrobial small molecules
- block intrinsic cellular pathways.
What factors can influence the interaction of the host and pathogen?
- genetic constitution
- physiological status
- environmental stress.
What are the stages in host recovery?
- Elimination of the pathogen
- Downregulation of immune responses
- Repair of tissue and/or organ damage
- Induction of immunity.
