Intro to microbiology Flashcards
How have pathogens shaped human evolution
-shaped immune system (we have to fight infections)
- Invaded genomes (endogenous retroviruses)
How do we catagorise pathogens
BSL-1
- Unlikely to cause disease
- GUT bacteria
BSL-2
- Can cause disease but unlikely to spread
- due to vaccination or high prevalence(chicken pox)
BSL-3
- Can cause disease AND Spread but treatments are available
- hepatitis C
BSL-4
- Deadliest!!!!!!!!!
- Causes serious disease, will spread and usually no treatment (example: Ebola virus)
Prions
What are prions
A mutant protein = Prion protein
Prions
What can prions do in the body
Can cause other normal proteins to fold abnormally (spongiform encephalopathy)
- Aggregates of abnormal proteins in the brain
- can cause degeneration of brain tissue
Prions
What is the normal prion called that we express on neuoronal tissues and tonsils
Prion protein (PrPc)
Prion
What is the abonormal prion protein called
PrPsc = is the abnormal protein
Prions
What diseases can prions cause
- Creutzfeldt-Jakob disease (CJD)
- Kuru
- Mad cow disease or vCJD
Prions
How can we pass down CJD
- Sporadic (mutation)
- Familial (passed down germline)
- Transmission (like mad cow disease vCJD)
Prions
How can CJD be transmitted
- Oral
- Operative (neuronal tissue)
- Blood
Prions: CJD
What are the treatments for CJD
It’s 100 % fatal
- No treatment
Prions
Why are infections caused by prions hard to treat?
- They have high resistance to disinfectants and heat
- Hard to remove and/or inactivate
Prions
What is kuru
like what is it a form of
Transmissible spongiform encephalopathy (TSE)
Prions
Where was kuru first identified
in Papua New Guinea in 1960’s
Prions
What is the cause of kuru
ritual of eating the dead (so it’s orally transmitted)
Prions
What is the cause of mad cow disease (vCJD)
Caused by feeding cows meat and bonemeal (oral)
Prions
Does mad cow disease only affect cows
Sheep can also get it
also humans
Prions
what prion can cause mad cow disease in humans
Bovine prion can cause disease in humans
Prions
Why do people think that mad cow disease may cause more deaths in the future
due to long incubation period
Viruses
What is the baltimore classification and
what does it classify based on
Classfies viruses
developed on how viruses synthesise their messenger RNA
Has 7 classes
Virus
What things do viruses have in common
- Same basic viral lifestyle
- **Alternative splicing,
- which increases the coding capacity of viral genomes
- Genome segmentation (most)**
- → this is better for evolution
- → E.G. viral genes are encoded on separate bits of DNA/RNA
- Host range
-> can be found across prokaryotes, eukaroytes and archea
some restricted to one host, others can jump into different species
Virus
Are viruses alives
Hm they are dead ish
- Not a cell
- Live in a shell or protein called a capsid
- Contain nucleic acids
- Can be enveloped or non-enveloped
- NEED a host to replicate!!!!
Virus
What is the viral lifestyle
Some variation due to genome and other factors
- Attach to host cell
- Entry into host cell
- Release of viral genome from capsid
- Replication of viral genome
- Assembly of new virions
- Eject the new virions from cell
- REPEAT !!!!
Virus
How can viruses effect host cells
- Some viruses integrate into the host genome (HIV)
- Cell death
- Due to production of lots of virions
- Cell fusion = syncytia
- Increased cell proliferation
- Papillomaviruses
- take over TFs
- Latent infection = no clinical manifestation until the virus reactivates (Herpesviruses)
Virus classifications
What is group 1
Give examples of viruses in this group
double stranded DNA virus
Herpesviruses, papillomaviruses, polyomaviruses & poxviruses
Viruses group 1
What is the Varicella Zoster Virus (VZV)
Causes chicken pox upon initial infection
Viruses group 1
Where is latency for VZV
Found in dorsal root ganglia
Group 1; dsDNA viruses
What can cause of reactvation the VZV
stress
Group 1; dsDNA viruses
When VZV gets reactivated what does it turn into
how does it also present
- Shingles
- pattern of rash shows which neurones are affected is latent VZV
Group 1; dsDNA viruses
Does the UK vaccinate against VZV
No
- UK does not but you can pay for the vaccine
- go down the route of chicken pox parties
Group II – ssDNA Viruses
What is the second group
single strand DNA viruses
Group II – ssDNA Viruses
Do single strand DNA viruses infect humans
Few do…but when they do they barley
Group II – ssDNA Viruses
What is the single strand DNA virus found in humans called
Torque Teno Virus
(formally transfusion transmitted virus)
Found in 90% of adults worldwide
Group II – ssDNA Viruses
What is most known Group II – ssDNA Viruse called
Parvoviruses
Canine parvo can kill young puppies
Group III – dsRNA Viruses
What is group 3 called
double strand RNA
Group III – dsRNA Viruses
Give example of double strand RNA virus
Rotaviruses
Can cause gastrointestinal issues like diarrhoea and vomiting
Group III – dsRNA Viruses
Rotaviruses can be very serious in babies and young kids
What do we do about it?
Rotavirus vaccine offered to babies
2x doses (1st at 8 weeks, 2nd at 12 weeks)
Group IV – ssRNA (+ve) RNA Viruses
What is group 4
single strand RNA virus
Can single strand RNA virus affect humans
Yes
Group IV – ssRNA (+ve) RNA Viruses
Give examples of single strand RNA viruses
noroviruses, enteroviruses, flaviviruses, coronaviruses, astroviruses
Group IV – ssRNA (+ve) RNA Viruses
Why is there a +ve on Group IV – ssRNA (+ve) RNA Viruses
Positive sense so genome is mRNA
Group IV – ssRNA (+ve) RNA Viruses
What type of group 4 virus is zika
flavivirus
can infect humans
Group IV – ssRNA (+ve) RNA Viruses
How can zika virus be transmitted
mosquitos & bodily fluids
Group IV – ssRNA (+ve) RNA Viruses
How do we treat zika virys
pain relief, rest and hydration
Group IV – ssRNA (+ve) RNA Viruses
what can zika virus cause
- Microcephaly in neonates
- Neurological disorders (Guillain-Barre syndrome)
Group V – ssRNA (-ve) RNA Viruses
What is group 5
Negative single strand RNA virus
Group V – ssRNA (-ve) RNA Viruses
Why are these the worst viruses
high % fatality rate
Group V – ssRNA (-ve) RNA Viruses
Give examples
Lyssavirus (Rabies), Influenza, Ebola, Marburg, Arenaviruses, Hantaviruses
Group V – ssRNA (-ve) RNA Viruses
What can ebola cause
haemorrhagic fevers
- Broad ranging symptoms
- typically characterised by blood in vomit/stools
Group V – ssRNA (-ve) RNA Viruses
What strai of ebola is the most common
Zaire strain
90% mortality
Group V – ssRNA (-ve) RNA Viruses
How do we end outbreaks of ebola
Infection control
Group VI – ssRNA-RT Viruses
What is group 6
single strand RNA viruses that have reverse transcriptase activity
- Viruses have DNA intermediate from RNA
- Reverse transcription
Group VI – ssRNA-RT Viruses
Give example of a group 5 virus
Human Immunodeficiency Virus 1 = HIV-1
HIV-1 is a lifelong infection progresses into AIDs
DNA stage (provirus) integrates into the host genome
Group VI – ssRNA-RT Viruses
AIDS is the failure of the immune system, what can happen as a result of this?
Other opportunistic pathogens can cause disease
Group VI – ssRNA-RT Viruses
HIV is known as zoonotic virus, how?
Originally jumped from chimps into humans
Restricted now due to human adaptation
Group VII – dsDNA-RT Viruses
What is group 7
double strand DNA and reverse transciptise
Why is group 7 known as “the weirdest group of viruses”
- they are DNA viruses but have an RNA intermediate step
- Use reverse transcription in virions to make their genomes
Group VII – dsDNA-RT Viruses
Give me an example of group 7 virus
Hepatitis B Virus
Group VII – dsDNA-RT Viruses
Why can Hep B be problamtic despite having an extremely good vaccine
- 95% plus of adults and older children can clear the acute infection
-Drops to ~ 5 % in young children where it becomes chronic
820K deaths due to HBV in 2019
Group VII – dsDNA-RT Viruses
What can Hep B go onto cause
hepatocellular carcinoma
Chronic carriers have a 40% chance of death from HCC due to infection
Bacteria
What is the realtionship between humans and bacteria
Not all bacterial species cause disease
- many can cause disease (but choose not to)
- others will always be pathogenic (they want to cause to disease)
- for example Salmonella Typhi has no reservoir outside of humans
- some are opperteruntic (if the chance to be the bad guy arises, then they will take)
- for example Pseudomonas will infect body if it has a chance
- anaerobes → can infect wounds if deep
Bacteria
Are bacteria versatile in their ranges of shape
Yes
for example they can be cocci, bacilli,
Bacteria
What is the general structure of bacteria
- Prokaryotes
- have no membrane bound organelles (like a nucleus)
- Usually have cell wall
- made out of peptidoglycan
- Can have appendages such as
- flagella
- frimbriae
Bacteira
How do we classfiy bacteria
Usually based on nucleic acids
but…
there is large divison (they are either gram negative or gram positive)
Bacteria
What is the difference between gram positive bacteria and gram negative
**Gram negative bacteria
**
- stain pink
- because have double membranes
- examples inc ecoli
**Gram positive **
- stain purple
- because have single membranes
- examples inc Staphylococci (E.G. MRSA) and Streptococci
Bacteria
How can bacteria cause disease
some bacteria invade cells(salmonella)
Toxin production, direct tissue damage
- Host response
- Immune system
Bacteria
What are bacterial toxins called and why do bacteria make them
- Exotoxins – proteins secreted by bacteria
- Synthesised for a number of reasons
- Destroy host cells
- Release cellular contents
- Allow invasion
Bacteria
Clostridium botulinum is a bacteria that produces toxins
What do these toxins do?
- Food poisoning
- Lethal neurotoxin that causes paralysis
- but we use it for botox
Bacteria
What is Lipopolysaccharide (LPS)
Endotoxin
- Found on Gram NEGATIVE bacteria
Bacteria
What does Lipopolysaccharide (LPS) do/cause
Major immune stimulator
- Causes Sepsis
- Only Lipid A is toxic
- which is what causes the major immune response
Specificty caused by terminal repeat reigons (salmonella has over 1000)
Bacteria
Why do bacteria have flagella and what do they do
- Use: Molecular motors used to swim
Why?
- Chemotaxis
- Can move bacteria towards or away from chemical attractants/repellents
Flagella are often immunogenic and cause inflammation
Important in pathogensis
Bacteria
What are fimbrae (Pili)
what are there functions
- Shorter and finer than flagella
- Have different functions
- Attachment to host cells (UTIs)
- Host cell invasion
- Roles in conjugation
- Conjugation = transfer of plasmid DNA
- This can drive AMR
Fungi
Are fungi single celluar or multicelluar
Both!
Fungi
Are fungi prokaryotic or eukaroytic
EUKARYOTIC
Fungi
Why are fungi harder to treat
Similar to human cells (since they are also eukaryotic)
Fungi
Do fungi have a cell wall
yes and it’s made out of chitin
Fungi
There are useful fungi though, can you give some examples
- Yeast
- Moulds
- Mushrooms
Fungi
What is the structure of Fungus
- Can be single cells but many grow as hyphae
- Cylindrical tubes which interconnect = mycelium
- Mycelium can be very large
-Armillaria ostoyae grows very large
there a national forest with 2,200 acres of fungi
Fungi
Fungal infections can act like pathogens and viruses
True or false
False
Can act as parasites or pathogens
Fungi
Can fungal infections be life threatning
Yes and No
we can have simple infections like athletes foot
some can be serious, life-threatening infections (E.G. Aspergillus infection in the lungs)
Fungi
What is the most common oral fungal condition
Thrush
Fungi
What fungus causes thrush
Candida albicans (a type of yeast)
Parasites
Are parasites always small
Parasites can also include larger, complex organisms
for example tapeworms
Parasites
An example of a parasite is protoza
Can you name two disease this can cause
- Malaria
- ## caused around 619,000 deaths
- Trypanosomes
- African Sleeping sickness
- fatal without treatment
