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Flashcards in Microbiology 7 Deck (19)
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1
Q

What is a quasi species.

A

In an infected person, there will be viral genomes which are slightly different as they evolve whilst in host.

2
Q

Certain quasi species may not make it through bottlenecks.

A

T.

Drug resistant person may infect someone who isn’t taking drug - virus may revert back to wild type.

3
Q

3 things that cause viruses to evolve fast.

A
  1. They replicate fast
  2. They replicate in high numbers
  3. They mutate often
4
Q

How do we prevent drug resistance?

A

HIV used as an example.

Give infected person protease inhibitor, yet a single nucleotide switch may render it useless.

COMBINATION of antiviral drugs given

Error rate = 1/10000 nucleotides

5
Q

HAART?

A

Highly Active Retroviral Therapy

6
Q

How do antibodies exert selection pressures on viruses?

A

There is a sub neutralising amount of antibody in a person, virus may mutate and now have a surface protein non-complementary to antibody (spike protein change).

7
Q

What is antigenic drift?

A

Antigens gradually change over a period of time due to antibodies exerting a selection pressure

8
Q

Whats special about rhinoviruses?

A

They don’t exhibit antigenic drift but there are lots of them circulating at once (120 antigenically distinct types)

9
Q

How do new viruses emerge?

A
  1. Zoonosis (from animals)
  2. Genetic variation
  3. Increased exposure - travel/world population
  4. Increased exposure - spread of vector
  5. New discoveries
10
Q

What are arboviruses?

A

A class of viruses transmitted to humans by arthropods (e.g. mosquitoes and ticks)

e.g.) yellow fever, dengue west nile, chikingunya

MANY ARBOVIRUSES ARE FLAVIVIRUSES

11
Q

What are flaviviruses?

A

Single strand positive-sense RNA genomes

12
Q

What is the vector of West Nile Virus?

A

CULEX TARSALIS

13
Q

What does West Nile Virus do?

A

Causes disease by going to the brain

14
Q

Describe Dengue haemorrhagic fever.

A
  1. There are 4 serotypes of dengue virus.
  2. Dengue first time is okay.
  3. But second time you get infected by dengue and its a different serotype then you’re in trouble.
  4. Antibody Dependent Enhancement of the Infection occurs.
  5. Dengue1 antibodies neutralised first infection.
  6. Dengue2 comes along, and Dengue1 antibodies bind to Dengue2. So the dengue isn’t blocked and the Fc receptors on immune cells can now bind to the antibody (inadvertently dengue too)
  7. This allows dengue to enter immune cells, causing a cytokine storm and dengue haemorrhagic fever.
15
Q

Chikungunya what is it associated with?

A

Arthralgia.

16
Q

Describe SARS.

Severe Acute Respiratory. Syndrome

A
  1. Transmitted via respiratory droplets.
  2. Nebulizers in hospitals made the situation worse
  3. Patients only contagious once they were symptomatic.
  4. It is a coronavirus
  5. Spike protein is highly plastic and can adapt to various receptors
  6. Binds to ACE-2 receptor in humans
17
Q

What is a coronavirus

A

Large(st) positive sense RNA genome

18
Q

What is MERS?

A
  1. Middle Eastern Resp Syndrome
  2. Coronavirus
  3. Originates from bats
  4. Closely related to HKU4 and HKU5
  5. Uses DPP4 receptor in lungs
19
Q

RECOMBINATION OF 2 OR MORE VIRUSES CAN COMBINE TO GIVE RISE TO A NEW VIRUS WITH DIFFERENT PROPERTIES.

A

T