1. Pathogenic Adaptations
Infectious Diseases Topic 2.5

2. Review- Controlling Pathogens

3. How do pathogens enter the human body?
Respiratory Surfaces
Wounds
Digestive System
Reproductive Organs
What are some common themes among these surfaces?
Moist?
Vulnerable?
Thin cells?

4. The Human Skin
The human skin is characterized with having different layers of cells (dead on top, healthy below) Note the rich blood supply and presence of sebaceous glands How does these work together to prevent pathogenic invasion?

5. Video: Human defense systems against Pathogens

6. Adaptations
Pathogens are able to change as aspect of themselves to facilitate their entry, survival and reproduction in hosts.
These can take on many different forms, for example:
Biofilms
Toxin production
Use of vectors

7. The most common example- the mosquito and its spread of MALARIA
Vectors
Vectors are organisms that do not cause disease themselves but spread the infection by conveying pathogens from one host to another.
The most common example- the mosquito and its spread of MALARIA

8. Note the way that malaria is spread on the right
Note the way that malaria is spread on the right. Why is it beneficial for the pathogen to survive inside of a host rather than be on its own?

9. Physical Adaptations

10. Biofilms
Bacteria spend most of their life in colonies known as ‘biofilms’, where they adopt a variety of physical properties. These properties protect the inner bacteria from being targeted by potentially damaging chemicals such as antibiotics

11. Toxin Production
Some pathogens are capable of secreting molecules that degrade the local environment, ensuring their colonization. An example of this is H. Pylori, which secretes toxins that degrade the lining of your stomach. This prevents the organism from clearing the infection.

12. Environmental adaptations

13. Surviving Inside of Cells
Some pathogens are capable of invading some host cells to prevent recognition by their immune cells. For example M. tuberculosis, which is taken into the lungs and hijacks white blood cells to prevent recognition by other immune cells.
What other benefits can be had from hiding in cells other than immune evasion?

14. Altering Host Behaviour

15. Drug Resistance
Many pathogens alter they physical characteristics so that they cannot be targeted by drugs. For example, antibiotics are the major ways of controlling bacterial infections. However, altering cell wall structure prevents antibiotic action- resistance

16. Molecular Recognition
Antigen
Molecular Recognition
Many pathogens are able to bind on to the surface of host cells through molecular recognition.
Coatings of pathogens, usually carbohydrates, have specific shapes that are complimentary to that of the host cells surface molecules.
Recognition of these molecules ensures that the pathogen has attached to the correct cells.

17. Respiratory Syncytial Virus

18. Exam Style Question
Many pathogens utilize vectors when spreading between different organisms
Describe the benefits of utilizing a vector
Describe one other way a pathogen may adapt to increase its spreading capability
Using a diagram, describe the process of molecular recognition and why it is key for pathogen spread