Pathogenic Adaptations Infectious Diseases Topic 2.5

Review- Controlling Pathogens

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?

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?

Video: Human defense systems against Pathogens

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

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

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?

Physical Adaptations

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

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.

Environmental adaptations

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?

Altering Host Behaviour

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

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.

Respiratory Syncytial Virus

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