Lecture 9: Challenges faced by the immune system and overview

Question 1

What are the different types of pathogen?

Answer 1

Bacteria, viruses, protozoa, parasites, fungi

Question 2

What do pathogens vary in?

Answer 2

size, location (intracellular/extracellular), biochemical composition

Question 3

Order pathogens in size order

Answer 3

Viruses

Intracellular bacteria

Extracellular bacteria, archaea, protozoa

Fungi

Parasites

Question 4

Name 3 extracellular pathogens

Answer 4

Streptococcus pneumonia

Clostridium tetani

Pneumocystis carinii

Question 5

What type of pathogen is Streptococcus pneumonia

Answer 5

Gram positive bacteria

Question 6

How many different serotypes are there of Streptococcus pneumonia?

Answer 6

More than 90

Question 7

What sorts of conditions can Streptococcus pneumonia cause?

Answer 7

acute sinusitis, otitis media, meningitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis … as well as pneumonia.

Question 8

is it true that Streptococcus pneumonia is part of the normal upper respiratory tract flora but can become pathogenic under the right conditions (e.g., immunosuppression)?

Answer 8

Yes

Question 9

What does Streptococcus pneumonia compete with?

Answer 9

Haemophilus influenzae (a Gram negative bacterium that can also cause pneumonia and meningitis)

Question 10

How does Streptococcus pneumonia compete with Haemophilus influenzae?

Answer 10

by attacking it with hydrogen peroxide.

Question 11

How does Haemophilus influenzae respond to attack from Streptococcus pneumonia ?

Answer 11

by signalling to our immune system to attack the S. pneumoniae

Question 12

What type of pathogen is Clostridium Tetani?

Answer 12

Gram-positive, spore-forming anaerobic bacterium.

Question 13

Describe the spores of Clostridium Tetani

Answer 13

extremely hardy, resistant to heat and most antiseptics, widely distributed in manured soils, on human skin and in contaminated heroin.

Question 14

What biological toxin is produced by Clostridium Tetani?

Answer 14

tetanospasmin

Question 15

What disease does Clostridium Tetani cause?

Answer 15

Tetanus

Question 16

What are the features of tetanus?

Answer 16

• risus sardonicus (a rigid smile),
• trismus (commonly known as “lock-jaw”),
• opisthotonus (rigid, arched back).

Question 17

In what percentage of cases is tetanus fatal in?

Answer 17

Around 40% of cases

Question 18

Is it true that a typical dose of tetanospasmin is too small to provoke an immune response?

Answer 18

Yes

Question 19

Give 3 examples of extracellular pathogens

Answer 19

Ascaris

Schistosoma

Trypanosoma brucei

Question 20

What type of pathogen is Ascaris?

Answer 20

Nematode roundworm parasite

Question 21

What disease is caused by Ascaris?

Answer 21

Ascariasis

Question 22

What type of pathogen is Schistosoma?

Answer 22

Trematode platyhelminth flatworm parasite

Question 23

Is it true that the pathogens in Ascariasis bury their way through the intestines and make their way up the lungs?

Answer 23

Yes

Question 24

What type of pathogen is Pneumocystis carinii?

Answer 24

Yeast- like fungus

Question 25

What type of disease is caused by Pneumocystis carinii?

Answer 25

Pneumocystis pneumonia

Question 26

What is the main type of ilness caused by Streptococcus pneumonia?

Answer 26

Pneumonia

Question 27

What disease does Schistosoma cause?

Answer 27

Schistosomiasis

Question 28

What type of pathogen is Trypanosoma brucei?

Answer 28

A protozoa

Question 29

What disease does Trypanosoma brucei cause?

Answer 29

Sleeping sickness

Question 30

What is the protozoan Trypanosoma brucei carried on?

Answer 30

Tsetse flies.

Question 31

Why is it difficult for our immune system to attach to the epithelial cells of protozoan Tsetse flies?

Answer 31

because they acquire a dense layer of glycoproteins that continually change, allowing the parasite to dodge an attack from the host’s immune system.

Question 32

What do the general symptoms of african sleeping sickness include?

Answer 32

Drowsiness, sleepiness (may be uncontrollable) Insomnia at night Anxiety, mood changes Fever, headache, sweating Swollen lymph nodes all over the body Weakness Without treatment, death may occur within 6 months from cardiac failure

Question 33

Name some intracellular pathogens

Answer 33

Mycobacterium leprae Leishmania donovani Plasmodium falciparum Variola Influenza Varicella

Question 34

What type of pathogen is variola?

Answer 34

Virus

Question 35

What disease does variola cause?

Answer 35

Smallpox

Question 36

What type of pathogen is influenza?

Answer 36

Virus

Question 37

what disease does influenza cause ?

Answer 37

The flu

Question 38

What type of pathogen is varicella?

Answer 38

Virus

Question 39

What disease does varicella cause ?

Answer 39

Chickenpox

Question 40

What type of pathogen is Mycobacterium leprae?

Answer 40

Gram positive bacterium

Question 41

What cells does Mycobacterium leprae infect?

Answer 41

Infects macrophages and Schwann cells

Question 42

What disease does Mycobacterium leprae cause?

Answer 42

Leprosy

Question 43

What type of pathogen is Leishmania donovani?

Answer 43

Protozoan

Question 44

What cells does Leishmania donovani infect?

Answer 44

macrophages

Question 45

what disease does Leishmania donovani cause?

Answer 45

Leishmaniasis

Question 46

What type of pathogen is Plasmodium falciparum?

Answer 46

Protozoan

Question 47

What cells does plasmodium falciparum infect?

Answer 47

erythrocytes

Question 48

What disease does plasmodium falciparum cause?

Answer 48

Malaria

Question 49

Is it true that viruses evolve and mutate very quickly?

Answer 49

Yes

Question 50

What 2 things can viruses do to avoid host immune responses?

Answer 50

They can mutate or recombine

Question 51

How does HIV evolve by mutation?

Answer 51

- HIV inserts its DNA into our cells when reverse transcriptase converts RNA to DNA - The viral DNA in our nucleus can then be transcribed into viral proteins

Question 52

Does HIV have a high mutation and antigenic drift rate?

Answer 52

Yes

Question 53

How does the flu evolve?

Answer 53

by recombination

Question 54

What is recombination?

Answer 54

Flu recombination refers to a process called genetic reassortment that occurs when two different strains of the influenza virus infect the same host cell and exchange genetic material. This can lead to the creation of a new hybrid virus with characteristics from both parent strains.

Question 55

When was the spanish flue first introduced?

Answer 55

In 1918

Question 56

What caused the 1918 spanish flu?

Answer 56

a bird crossing the species barrier and transferring H1N1 bird flu

Question 57

Which influenza infects humans?

Answer 57

Influenza type A

Question 58

What triggered the 1957 Asian ‘flu epidemic?

Answer 58

Recombination events

Question 59

What is antigenic shift?

Answer 59

When pathogens alter their antigens, making it harder for the immune system to deal with them

Question 60

What pathogen undergoes antigenic shift?

Answer 60

Plasmodium falciparum

Question 61

Why do we have to rely on our innate immune system for the first few days after being infected with a pathogen?

Answer 61

Because the primary response and the secondary response are slow

Question 62

What does the immune system find it difficult to distinguish between?

Answer 62

Self, non-self, and altered self

Question 63

What do 'altererd self' include?

Answer 63

malignant cells, apoptotic cells, oxidised proteins

Question 64

What are the typical features of non-self?

Answer 64

Bacterial cell wall structures Protein and peptide structures/sequences from pathogens Yeast carbohydrates Pathogen DNA Viral antigens on host cells

Question 65

What does the blood brain barrier do?

Answer 65

It separates circulating blood from the brain extracellular fluid.