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Semester 2 > Molecular Virology > Flashcards

Molecular Virology Flashcards

0
Q

What does AIDS stand for?

A

Acquired immunodeficiency syndrome

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1
Q

What cell does HIV infect

A

CD4+

T-lymphocytes, monocytes, macrophages, dendritic cells

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2
Q

How can AIDS be defined

A

The progressive qualitative and quantitative decline in the CD4+ Th1 lymphocyte subset

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3
Q

Estimated cumulative number of deaths due to HIV

A

30 million

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4
Q

Where is HIV mainly pandemic?

A

Sub-Saharan Africa

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5
Q

When was the peak of the number of people newly infected and where are we at today

A

1997

New infections have reduced by 27%

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6
Q

What is the target of the organisation called UNIAIDS

A

To reach 0 new cases by December 2015

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7
Q

When was HIV first identified?

A

1980

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8
Q

When was first isolated?

A

1983

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9
Q

What was the first discovered HUMAN retro virus?

A

HTLV-1 in the late 1970’s

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10
Q

What was HIV first called?

A

LAV/HTLV-3

It was also found to not be closely related to HTLV-1

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11
Q

When was HIV’s genome completely sequenced

A

1985

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12
Q

What SIV virus was HIV-2 found to be closely related too?

A

SIVsm

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13
Q

Name the 4 HIV-1 virus groups

A

M, N, O, P

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14
Q

HIV-1 Group M

A

M = main group
Responsible for 98% of infect patients
A diverse group with sub types A-K

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15
Q

Where is the epicentre of diversity of the HIV-1 virus

A

Cameroon

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16
Q

What does HIV-1 O group stand for

A

Outlier

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17
Q

HIV-1 groups N and O most closely related virus?

A

SIVcpzPtt

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18
Q

HIV-1 group P most closely related virus?

A

SIVgor

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19
Q

SIVcpz is a recombinant virus of which two viruses?

A

SIVrcm and SIVgsn

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20
Q

How is it believed HIV-1 was transmitted to humans?

A

SIVcpz virus

Bushmeat trade

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21
Q

What 3 causes are believed to be responsible for HIV-1 rapid spread within the population

A

Intravenous drug use
Blood transfusion
International travel

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22
Q

How is HIV transmitted to other people?

A

Contact with blood or mucous membrane

Eg sex, blood transfusion

23
Q

What is transmission rate of HIV via sexual contact?

A

1-1000 per sexual partners

24
Q

Why is the transmission of HIV very inefficient?

A

Mucosal layer provides physical barrier and is the front line innate immune response
Also due to limited target cell availability

25
Q

Does HIV infection occur from a founder virus?

A

Yes, and there is strong evidence to support this

26
Q

What are the risk factors for sexual transmission of HIV-1

A

High virus load
Presence of cuts, abrasions, irritation, inflammation
Other STD (herpes, syphilis)
Lack of or failure of condom

27
Q

Mother to child transmission

A

Accounts for greater than 90% of infant/child infections.
Can be as high as 50% of births to HIV positive mothers
Highest risk during delivery but breast feeding is also significant route of infection

28
Q

Application of antiretroviral therapy and avoidance of breast feeding. How does affect transmission

A

Reduces rates of transmission to 2%

29
Q

HIV home test kits?

A

Rely on the innate immune response, as they detect antibodies
Provide fast results 20 mins
99% accurate

30
Q

If a HIV kit test is positive how is this followed up?

A

A lab test: ELSIA, westernblot

Then use RT-PCR to confirm isolate and look for drug resistance. So optimal treatment can be given

31
Q

What is the length of HIV-1 genome?

A

9.3 Kb

32
Q

HIV-1 genome is flanked by what at each side of the genome?

A

LTR

These act both as promotors and poly A signals

33
Q

Name all the genes in HIV-1 genome

A 
Gag
Pol
Env
Vif
Vpr
Vpu
Nef
Tat x2
Rev x2
34
Q

What genes does murine leukaemia virus contain?

A

Gag, pol and env

35
Q

What is the structure of the CD4+ receptor?

A

4 Extracellular IgG like domain and a cytoplasmic tail

36
Q

What us the structure of the secondary receptors (CCR5 CxCR4).

A

7 transmembrane helices, virus interacts with the N terminus of the protein

37
Q

Is integrase a tetramer or a dimer?

A

Tetramer

38
Q

Tat

A

86-101 amino acid

A nucleolar protein

39
Q

Tat functions

A

RNA binding protein-transcriptional activator
Activation of quiescent T cells
Induction of apoptosis

40
Q

What is the name of the stem loop at the beginning of the HIV genome?

A

TAR RNA

41
Q

Molecular basis of Tat

A

Tat recruits host proteins such as cyclin T1 and cdk9
This phosphorylates the RNA pol
Phosphorylation of C-terminus tail of RNA pol II allows elongation.

42
Q

Where does the RNA pol II bind

A

TATAA box

43
Q

What is the function of Rev?

A

Controls the translation of viral mRNA and movement form the nucleus to the cytoplasm

44
Q

What sequence does Rev bind and where is this sequence in the HIV genome?

A

RRE sequence

Found in the envelope protein reading frame

45
Q

What spliced transcripts is the RRE sequence found in?

A

Full length and single spliced

NOT multiply spliced transcripts

46
Q

What does RRE stand for

A

Rev responsive element

47
Q

Structure of the RRE?

A

351bp hilly structured RNA

48
Q

Name HIV-1 accessory protein (non essential)

A

Vif, Vpr, Vpu and Nef

49
Q

What accessory protein does HIV-2 have that is not present in HIV-1

A

Vpx

50
Q

Roles of Vif, Vpu and Vpx?

A

Key roles in counteracting the innate anti-viral response

51
Q

Role of Vpr?

A

Induces G2 cell cycle arrest

52
Q

What technique is often used to study the functions of genes

A

Reverse genetics

53
Q

How is Nef stabilised in the PM?

A

Nef has a myristoylated end that anchors the protein into the plasma membrane

54
Q

Main roles of Nef

A

Down modulation of cell surface glycoproteins eg CD4, MHC class I
Enhancement of viral infectivity
Perturbation of cell signalling

55
Q

Why is down modulation by HIV Nef important?

A

Prevent sequestration of virus on cell surface
Prevent incorporation of CD4 into new virion envelopes
IL16 signalling via CD4 inhibits LTR activity so is blocked
Block to lethal superinfection

Semester 2 (4 decks)

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