Viral pathogens 2 Flashcards Preview

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Flashcards in Viral pathogens 2 Deck (24)
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1
Q

What do viruses need in order to replicate?

A

In order to replicate, viruses need to find host cells

2
Q

What do viruses replicate in?

A

• Viruses replicate in specific cells for specific reasons and to allow its transmission and pathogenesis

3
Q

Why are CD4+ key in the immune response to HIV?

A

• CD4+ are key in the immune response to HIV infection as the course of HIV infection goes on, you get less CD4+ T cells and more viral RNA genomes

4
Q

What happens to levels of CD4+, 10 years after the infection of HIV-1?

A

• 10 years after the infection, you have almost undetectable levels of CD4+ T cells and large numbers of copies of the RNA genome reaching an end point

5
Q

What do viruses do to evade the immune response?

A

• To evade this immune response, viruses replicate in the immune cell whose function is to recognise and kill infected cells

6
Q

What does replication of viruses in the immune cell hide the virus from?

A

• Replication in the immune cells hides the virus from the immune cells and inhibits immune cell function

7
Q

What does inhibition of immune cell function allow other pathogens to do ?

A

• Inhibition of immune cell function allows other pathogens to replicate in virus infected hosts.
§This allows disease to occur

8
Q

What are the 2 types of CD4 T cells that virus enter?

A

• Virus enters CD4 T cells(Non-permissive CD4 T cells/permissive CD4 T cells)

9
Q

What are permissive CD4 T cells?

A

• Permissive CD4 T cells are cells In which the virus can fully replicate

10
Q

What are non-permissive CD4 T cells?

A

• Non-permissive CD4 T cells are cells in which the virus can’t fully replicate

11
Q

What happens once virus enters permissive CD4 T cells?

A

• Once virus enters cell and converts its RNA into dsDNA, it infects the nucleus

12
Q

What mechanism does the CD4 T cell have and what does this activate, trigger and cause?

A

• Host cell has mechanisms in place which recognise this DNA as foreign and activates caspase-3, which triggers apoptosis, causing CD4 T cells to die
§This plays a small role in CD4 T+ cell depletion and this response is mostly not successful

13
Q

What happens when virus enters non-permissive CD4 T cells?

A

• Virus enters but doesn’t replicate fully and this leads to the accumulation of incomplete reverse transcriptase

14
Q

What does the IFI16 DNA sensor recognise and what does it activate?

A

• IFI16 DNA sensor recognises the foreign nucleic acids which activates innate antiviral response, inflammatory responses and inflammasome response
§This activates Caspase-1 which leads to pyroptosis and hence cell death occurs as well as the excretion of immune molecules to warn neighbouring cells of the infection

15
Q

What does HIV infection lead to and cause?

A

• HIV infection leads to pyroptosis and causes:

-CD4 T cell death and release of pro-inflammatory cytokine + cellular contents which causes inflammation

16
Q

What is direct activation of immune system through?

A

• Direct activation of immune system through cell death

17
Q

What is indirect activation of immune system through?

A

• Indirect activation of immune system through pro-inflammatory cytokine release

18
Q

What is primary infection?

A

When you’ve never been exposed to pathogen before and so exposure allows virus to replicate and can typically be resolved by immune suppression

19
Q

Why does an infection become latent?

A

• Infection then moves to areas in which immune system can’t access and hence becomes latent

20
Q

What does reactivation from latency occur upon?

A

• Reactivation from latency occurs upon immunodeficiency and the immune system is no longer suppressing the virus

21
Q

HSV

A
  • HSV moves into the nervous system and a lack of immune surveillance here as immune cells don’t access the blood brain barrier
  • HSV remains there without replication, ready for immunodeficiency
22
Q

What happens when KSHV enters cell?

A

• KSHV enters cell and KS progenitor cells are produced.
○ This is a primary infection
○ There’s latent infection of V cells
○ KSHV continues replicating slowly

23
Q

What happens to interactions between T cells and B cells due to HIV?

A

○ HIV leads to T cells depletion hence interaction no longer occurs
○ Virus in the B cell reactivates

24
Q

What happens if KS enters a non-permissive B cell?

A

○ KS progenitor cells produced
○ Latent infection of B cells but no transformation
○ Requires an inflammatory signal to reactivate from latency
○ Some of these cells become oncogenic