19: Microbes Causing Human Disease (syphilis)

Question 1

What are the different subspecies of treponema?

Answer 1

• the genus treponema contains both pathogenic and nonpathogenic species
• human pathogens cause four treponomatoses: syphilis, yaws, endemic syphilis and pinta

Question 2

What are the different stages of syphilis infection?

Answer 2

There are four stages of syphilis (primary, secondary, latent and tertiary). Each stage has different signs and symptoms

Question 3

What are PAMPS and give examples

Answer 3

PAMPS = pathogen associated molecular pattern molecules

Eg. Lipopolysaccharide (LPS) are a diverse set of microbial molecules that share a number of different general ‘patterns’ r structures that alert immune cells to destroy intruding pathogens

Question 4

Describe the structure of TPA

Answer 4

• tPA is a 70kDa protein secreted in a pro enzyme form that is also converted by plasmid to the active two chain form
• the tPA molecule has four functionally distinct domains, these include fibronectin like or finger domain, an EGF like domain, two Kringle domains and a serine protease domain

Question 5

How do macrophages response to tPA infection?

Answer 5

• macrophages interact with T cells in order to bring about T cell activation in target organs and are themselves activated by inflammatory messenger molecules (cytokines) produced by the T cells
• macrophages produce toxic chemicals such as nitric oxide that can kill surrounding cells

Question 6

What is monomorphic?

Answer 6

Having but a single form; retaining the same form throughout the various stages of development; of the same or of an essentially similar type of structure

Question 7

How has tPA adapted to its environment

Answer 7

• undergone adaptations that enable it to acquire all of its required nutrients and optimise their usage in diverse niches
• small genetic changes can result in profound changes in pathogenesis and host range

Question 8

How does tPA bind to host cells?

Answer 8

• tPA binds fibrin through its fibronectin type II domain and the two Kringle domains

Question 9

Detail the OM and OMP’s of tPA

Answer 9

• TPA interacts with cell membrane embedding within the OM (outer membrane) due to its hydrophobic nature
• this integration disturbs the membranes integrity leading to altered fluidity and permeability.
• TPA also influences the function of the OMPs (outer membrane proteins) impacting their structure and function
• the presence of TPA affects the organisation and stability of the oMPS contributing to cellular changes and influencing cellular response