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Flashcards in Microbiology 6 Deck (26)
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1
Q

What is prophylaxis?

A

Preventing disease before the aetiologic agent is acquired, by giving vaccination or drug before infection

2
Q

What is therapy?

A

Treating disease after patient infected

3
Q

2 examples of successful virus vaccination?

A

Polio and smallpox

4
Q

What is a live attenuated virus vaccine?

A

Natural virus with genome, but decreased virulence so only mild infection to initiate immune response

5
Q

What is an inactivated virus vaccine?

A

Parental virus treated with chemicals and heat - GENOME DESTROYED.

But proteins still present so once injected the body still recognises the viral proteins and produces an immune response.

More difficult to get a response from this type of vaccine so ADJUVANTS may be added.

6
Q

What is a purified subunit vaccine?

A

Parental genome treated with proteases - becomes little pieces.

These viral subunits contain antigens that can trigger an immune response.

7
Q

How is cloning used for vaccination?

A

Parts of original viral genome cloned inside bacteria.
DNA can be put into virus-like particles (e.g. HPV vaccine)
Viral DNA may be injected into people.
May create new virus which doesn’t make people ill but has an OG viral segment.

8
Q

Explain how viruses can be attenuated to make live virus vaccines.

A
  1. Isolate pathogenic virus from patient.
  2. Grow in human cultured cells.
  3. Take this cultured virus and infect monkey cells.
  4. The viral genome will gradually adapt to the monkey cells and will become a monkey virus, and no longer grows well in humans
9
Q

What are the pros and cons of live attenuated vaccines.

A

+ rapid broad, long lived immunity
+Dose sparing
+Cellular immunity

  • requires attenuation
  • may revert
10
Q

What are the pros and cons of inactivated vaccine?

A

+Safe
+can be made from wild type virus

  • frequent boosting required
  • high doses needed
11
Q

Give an example for which both live and inactivated vaccines are available.

A

Influenza, Polio

12
Q

Talk about influenza vaccination.

A
  1. Inactivated vaccine/subunit vaccine consists of only spike proteins (HA).
  2. Given to people at risk
  3. DOES NOT GIVE YOU FLU

What about live attenuated vaccination for children?

Cold adapted - can replicate at 32 degrees (nose) but not at 37 degrees. Given as nasal spray.

13
Q

Poliovirus vaccination?

A

Inactivated form is SALK inactivated vaccine.
-Virus treated so can no longer replicate, but high dose needed so isn’t that good

Live attenuated form - SABIN

  • This form is better
  • 1/7 can result in poliomyelitis
  • If given to immunosuppressed, they may get a persisting infection
14
Q

How do you get a viable recombinant attenuated virus vaccine?

A
  1. Viruses consist of 3 genes; Receptor-binding gene, virulence gene, capsid protein genes.
  2. If you mutate/delete the virulence gene, you have an immunogenic but not virulent vaccine
15
Q

Talk to me about the Rotavirus vaccine.

A

Rotarix is a live attenuated rotavirus reassortant vaccine.

Its sick in preventing diarrhoea and vomiting, but it can cause intussusception (bowel blockage) in older babies.

Therefore, vaccine only given to babies <15weeks

16
Q

Name some subunit vaccines.

A

Hep B

HPV

17
Q

Talk to me bout the shingles vaccine.

A

Painful rash resulting from reactivated varicella zoster (chicken pox) virus.

More common in elderly.

Pain may persist even after rash goes as Post Herpetic Neuralgia.
Live attenuated vaccine is similarly different from chicken pox vaccine.

Only given to 70-79 y/o

18
Q

We can use other viruses as vectors for proteins present in viruses that affect us. e.g. canary virus HIV

A

T

19
Q

Antiviral treatment. Talk to me

A

Interferons - switch on natural antiviral response. However, they also switch on inflammation and fever.

So giving interferons suppresses virus but may make patient feel worse.

May just treat symptomatically

20
Q

Talk to me about Acyclovir.

A
  1. Nucleoside analogue
  2. Viruses have to replicate their genome by adding nucleotides/nucleosides.
  3. Acyclovir looks like Guanosine but it is missing the bottom half of the ring.
  4. This eventually stops viral DNA replication.

SEE TUTORIAL 1

THE GOOD THING IS THAT IT IS ONLY ACTIVE IN VIRUS INFECTED CELLS

21
Q

What are the 2 strategies to inhibit influenza based on?

A

Inhibiting the M2 channel.

  1. Low pH inside endosome activates M2 channel.
  2. M2 channel on virus capsid opens. This allows protons to move into virus and undo the bonds holding capsid together. So the virus uncoats and releases contents into cell cytoplasm.
  3. BUT IF M2 BLOCKED, VIRUS BLOCKED and remains in its shell.
22
Q

What are amantadines?

A
  1. Amantadines (and rimantadines) are the right shape to fit M2 channel and wedge in there. They prevent protons from flowing through M2 channel.
  2. BUT it can be undone by a single point mutation in the viral genome.
  3. ALL STRAINS ARE NOW AMANTADINE resistant
23
Q

What are neuraminidase?

A
  1. Produced by influenzas
  2. Viruses enter new cells by binding to Sialic acid.
  3. As the virus infects the cell, the cell gradually dies.
  4. New viruses leave the cell and want healthier cells, so they produce Neuraminidase which binds to and destroys sialic acid on the cell surface.
  5. They destroy sialic acid so the daughter cells are less likely to infect this original cell.
  6. BUT if we inhibit neuraminidase, the enzymes will go back to the old cell and will not spread - helps contain infection within the patient.

e.g.) Zanamivir (Relenza), Oseltamivir (Tamiflu)

24
Q

What are the stages of the HIV life cycle?

A
  1. Binding and entry
  2. Reverse Transcriptase
  3. Integration
  4. Transcription
  5. Translation
  6. Virion assembly
  7. Budding and exit

THESE ARE ALL STAGES OF HIV TREATMENT

25
Q

What are some HIV retrovirals?

A
  1. Nucleoside Reverse Transcriptase Inhibitor (NRTI)
  2. Non-nucleoside Reverse Transcriptase Inhibitor (NNRTI)
  3. Integrase inhibitor
  4. Entry inhibitor (e.g. CC45, CXCR4 blocks interaction)
  5. Protease inhibitors
26
Q

What Hep C treatment is there?

A

NS3-4A is a viral protease that processes the polyprotein. Initially, protease inhibitors such as telaprivir and boceprivir were used, but unsuccessful as mono therapy.

New targets:

  • NS5B (viral polymerase that replicates RNA genome)
  • NS5A (phosphoprotein that virus requires for replication)

New therapy combines a protease inhibitor, NS5A inhibitor (sometimes interferon or Ribavirin given)