The Antisocial Microbe - Introduction To Pathogens

Question 1

Cellular types of pathogen

Answer 1

Single celled (fungi/protists)
Multicellular eukaryotes (tapeworm etc)
Bacteria 🦠

Question 2

Acellular types of pathogen

Answer 2

Viruses (including bacteriophage)

Prions

Question 3

What is a prion pathogen

Answer 3

An infectious particle made up of misfolded proteins

Question 4

Example of a prion disease

Answer 4

Kuru

Question 5

What is a bacteriophage

Answer 5

A virus that infects and replicates within bacteria and archaea

Question 6

Explain lytic bacteriophage life cycle (4)

Answer 6

1. Phage from environment infects bacterial host
2. They replicate inside the host at its expense
3. Bacterial lysis (death) and phage particles are released back into environment
4. New phage particles infect another bacterial host

Question 7

Main difference between lytic and lysogenic cycle

Answer 7

Lytic cycle destroys host cell but lysogenic cycle does not

Question 8

Lytic phage

Answer 8

Bacterial cell lysed and viral progeny leaves host to find new hosts to infect

Question 9

Lysogenic phage

Answer 9

Bacterial host not lysed. Viral genome integrates within host DNA and replicates alongside it

Question 10

Most abundant biological entity on the planet?

Answer 10

10^30 bacteriophages

Question 11

What do many pathogens require?

Answer 11

Host to host transmission because they don’t reside in an environmental reservoir

Question 12

Example of a pathogen that reside permanently in a host without an environmental reservoir

Answer 12

Chlamydia trachomatis

Question 13

Vertical transmission

Answer 13

Passing of infections from parent to offspring

Question 14

Horizontal transmission

Answer 14

Passing of infections among different individuals

Question 15

Example of vertical transmission of pathogens in humans

Answer 15

Transfer of a pathogen from a pregnant woman to her foetus

Transfer of pathogen from mother to infant while breastfeeding

Question 16

Three types of complications that vertical transmission of pathogens in humans can cause

Answer 16

Congenital - infection during pregnancy and can be transferred to foetus

Neonatal - serious complications shortly after birth

Maternal - severe disease during pregnancy but not transmitted

Question 17

Example of a virus that hosts can become immune to

Answer 17

Measles virus

Question 18

Once infected with measles …

Answer 18

A single infection of measles provides long term immunity

Question 19

Acute infections

Answer 19

Occur in short period of time, in this time they pas in to new host

Question 20

Chronic infection

Answer 20

Pathogen remains dormant in host but can be reactivated to become infectious

Question 21

What’s a disadvantage of acute infections

Answer 21

The pathogen is vulnerable because the host might die or gain immunity

But in chronic infection the pathogen can live there for a while

i think slide 9

Question 22

What causes chicken pox and shingles?

Answer 22

Varicella zoster virus

Question 23

Before shingles occurs where is the virus dormant

Answer 23

In the sensory ganglia

Then it’s reactivated

Question 24

How does varicella zoster virus spread

Answer 24

Local replication, lymphoid tissues, T cells

Question 25

What are dead end hosts

Answer 25

Species which have received pathogen for one host but are not able to pass on transmission of this pathogen

Question 26

Pathogen that evolved in one host species can occasionally do what

Answer 26

Infect another host species (this host species may be able to continue to transmit the pathogen or may not - in that case it’s a dead end host)

Question 27

When might a novel infectious cycle emerge

Answer 27

If a pathogen in one host infects another host (different species) and this second host is able to transmit the pathogen

Question 28

How does rabies spread long hosts

Answer 28

Biting

Grows in the salivary glands

Question 29

How does the rabies virus move within the host

Answer 29

Intracellularly in the nervous system

Question 30

What would a complex life cycle of a pathogen involve

Answer 30

Multiple species (host isn’t just a single species)

Question 31

Why are complex life cycles of pathogens involving multiple species costly?

Answer 31

Pathogen have to survive in a variety of different environments and evade a variety of different immune responses

Question 32

Transmission cycle of schistosomiasis

Answer 32

Humans infected by contact with contaminated water

Pathogen penetrates skin of host

Migrates through tissues and resides in veins

Eggs deposited in intestine and released into environment through urine/faeces

Eggs hatch into miracida which infect snails (intermediate host)

Growth of sporocysts in snail and then release of pathogen completing life cycle

Question 33

Pathogen that causes cervical cancer

Answer 33

Human papillomaviruses

Question 34

How can microbes cause cancer

Indirect
Direct

Answer 34

Indirect - production of toxic products

Direct - alteration of host cells

Question 35

A few cancers are what

Answer 35

Infectious

Eg. Devil facial tumour disease

Question 36

Devil facial tumour disease

Answer 36

Aggressive nonviral clonally transmissible cancer which affects Tasmanian devils

Question 37

Autocatalytic

Answer 37

One product of a reaction is a catalyse for the same reaction or a coupled reaction

Question 38

How is prion protein produced

Answer 38

By normal host cells

Question 39

How can prions be transmitted

Answer 39

Orally

Question 40

Why are prions unusual

Answer 40

Infection is a particular part of the protein and high is naturally present in mammalian brains

Question 41

Key point summary

Answer 41

Microbial diseases major source of global morbidity

Microbial pathogens evolved multiple times on tree of life

Predominantly infectious

Many elaborations of infectious and pathogenic lifestyle

Pathogens can have diverse effects on hosts - some necessary for survival and some incidental