Genetics of Human Pathogens Flashcards
Define pathogenicity
the ability of a pathogen to cause disease in a host.
Define virulence
the severity of the disease a pathogen causes.
In a growing population…
…new diseases are inevitably going to emerge.
Innate immune response is the…
…skin
What must a pathogen do for success?
Colonise the host
Locate a nutritionally compatible niche (in order to grow and reproduce, moves towards the nutritents)
Evade host immune response (innate and adaptive)
Replicate (using host resources)
Exit and spread to new host ( coughs, sneezes, other symptoms like diarrhea).
Types of Human Pathogens
Bacteria (Vibrio cholerae – cholera, 1.3 to 4.0 million cases)
Viruses (varicella-zoster virus – chicken pox)
Protists (protozoa - Plasmodium falciparum – malaria)
Fungi (Aspergillus species – lung infections)
Parasitic worms (flatworms, roundworms)
Prions (proteinaceous infectious particle - Creutzfeldt-Jakob disease )
Function of cell wall in prokaryotes?
maintains shape of bacteria cell
Cell capsule function in prokaryotes?
protects cell from immune response – acts as a shield
Prokaryotes contain dna in the form of a…
…circular chromosome.
Describe endotoxins
They are part of the bacterias cell wall
They are released from a bacteria once the cell wall is compromised and the bacteria dies.
This triggers the immune system
Endotoxins can also be released during spore formation
Describe exotoxins.
Released by bacteria into the environment
Polypeptide proteins
Deliberately released
Mostly released by gram +ve bacteria.
Define Lysis
when a bacteria cell dies/breaks down. This causes the release of more pathogenic agents.
How can viruses hide from cells?
Viruses can hide from cells by putting their dna into the chromosomes of a cell.
What is the name of the pathogen which causes malaria?
Plasmodium falciparum
In what temps do fungi thrive in?
Fungi thrive in lower temperatures, not higher temperatures.
Whats the name of the fungi pathogen?
Aspergillus fumigatus
How do u get Aspergillus fumigatus
(fungi)?
from breathing in aspergillus fumigatus fungus which is found in soil
How common is Aspergillus fumigatus ?
Rare
Who most likely to get Aspergillus fumigatus?
immunocompromised individuals are most likely to get this. For example, someone who already has aids.
Where do parasitic worms survive in the body?
Worms are able to survive the conditions of the stomach.
How does someone get parasitic worms?
You can get this from undercooked food eg burgers.
How do worms increase in number?
The worm secretes lots of eggs in the stomach. They have these in sacs – proglottid.
Whats CJD caused by?
prions
WHats a prion?
abnormal, pathogenic agents that are transmissible and induce abnormal
folding of specific normal cellular proteins called prion proteins that are found most abundantly in the brain.
Endo/exo toxins are critical to…
…the growth and replication of cholera. Key to its pathogenicity.
Whats TCP?
a spike protein sticking out of the surface of the bacteria. ( type 4 in cholera ). Important for colonisation.
Main symptoms of cholera?
watery diarrhoea due to increase of water secretion from lumen into the gut.
Why is diarrhoea effective for spread of bacteria?
This is there exit route which is their way of spreading, making them an effective and fit bacteria.
Whats a plasmid?
A plasmid is a small DNA molecule which is extra to the chromosome. Contains very few genes but can give the bacteria and evolutionary advantage.
What do virulence genes encode for?
virulence factors (proteins)
