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CBI - UOE > HIV infection mechanism > Flashcards

HIV infection mechanism Flashcards

1
Q

AIDS is caused by

A

HIV

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2
Q

HIV infects and destroys

A

CD4 T cells

- important for antibody response

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3
Q

AIDS was originally called

A

GRID

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4
Q

when first reconised

A

1980s in the US in intravenous drug users and gay men with no apparent cause for impaired immunity but who showed symptoms of Pneumocytstics carniii pneumonia (PCP)

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5
Q

how many people infected per year in us

A

50,000

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6
Q

how many deaths globally since 8s

A

39+ mill

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7
Q

2 mill new cases in

A

2014

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8
Q

how many people infected in sub-saharan africa

A

2/3

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9
Q

how many infected in asia

A

1/5th

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10
Q

most aids is caused by

A

HIV-1

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11
Q

HLR-DR stands for

A

Human Leukocyte Antigen - antigen D Related

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12
Q

HLR-DR acts as

A

ligands for TCRs

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13
Q

where did HIV originate

A

southern cameroon from a simian immunodeficiency virus

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14
Q

SIV

A

simian immunodeficiency virus

- a retrovirus that infects non-human primates

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15
Q

how was SIVcpz intruded into human

A

through bushmeat activities with subsequent mutation into HIV- required one or more high risk transmission channels for human to human spread

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16
Q

why were these transmission channels absent in africa prior to 20th century

A

growth of large Colonial African cities led to societal changes such as prostitution (increasing frequency of STDs- e.g. syphilis) that allowed sexually transmitted infection.

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17
Q

earliest documented case of HIV in the congo

A

1959

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18
Q

origin of AIDS pandemic traced back to

A

1920 in city of Kinshasa in Congo

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19
Q

Pneumocystis pneumonia

A

a form of pneumoniaa caused by yeast like fungus - Pneumocystis jiroveciii

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20
Q

Pneumocystis jiroveciii

A

commonly found in lungs of healthy, but source of opportunistic infection in immunocompromised patents

21
Q

Pneumocystis jiroveciii especially seen in

A

those undergoing chemotherapy, HIV/AIDS and the use of medication that affects the immune system

22
Q

cryptococcal meningitis is caused by

A

Crypotococcus gattii and neoformans

23
Q

Cryptococcal meningitis prevalence

A
  • Around 950,000 cases worldwide
  • 600,000 deaths
  • 70% in sub-Saharan Africa

usually just effects the immunocompromosied patients, however can affect the healthy

24
Q

Aids and microbial infections: brain

A

Toxoplasmosis

Cryptocooccal meningitis

25
Q

Aids and microbial infections: Eyes

A

Cytomegalovirus

26
Q

Aids and microbial infections:mouth and throat

A

Candidiasis (yeast)

27
Q

Aids and microbial infections: lungs

A

Pneumocytist carinii pneumonia
TB
Histoplasmosis

28
Q

Aids and microbial infections: gut

A

Cytomegalovirus
Cryptosporidiosis
Mycobacterium avid complex

29
Q

Aids and microbial infections: skin

A

herpex simplex

shingles

30
Q

Aids and microbial infections: genitals

A

Genital Herpes
Human papillomavirus
Vaginal Candidiasis

31
Q

HIV- epithelia entry

A
  • crosses through M cells- prevalent in tonsils and rectal epithelial
  • can gain access via epithelia damage and ulcerative infection by trauma or injection
32
Q

vaginal epithelial lack

A

M cells- the way HIV usually gain access

- instead HIV gains access via interdigitating processes on Langerhans cells

33
Q

pithelial cells in the small intestine express

A

CCR5 chemokine receptors

34
Q

HIV-1 binds to which receptor

A

CCR5 bia the trial envelope glycoprotein GP120 and the virus is trancytosies

35
Q

HIV epithelia entry summary example

A

o HIV-1 bind to CCR5 (once tethered by galactosylceramide) via the viral envelope glycoprotein gp120 and he virus is transcytosed
o Once across mucosal barriers, HIV-1 encounter sub-epithelial dendritic cells
o C-type lectin (CLRs) on dendritic cells bind high mannose N-linked oligosaccharides on viral envelope glycoprotein gp120
o Interaction with CLRs initiates dendritic cell migration to regional lymph nodes
o Once in lymph nodes, intact virus, internalised with CLRs , is re- exposed at the surface and displayed to T cells

36
Q

regardless of route of infection

A

o predominant site of virus replication early in disease is in the s.intestine- this reflects the large number of activated T cells, that express CCR5 in that organ

37
Q

entry of HIV into cells is mediated by

A

viral envelope glycoprotein gp120.

  • Binds to CD4 and chemokine receptors (CCR5 or CXCR4) on host surfaces.
  • Binding with receptor leas to a conformational change in gp120 that exposes the transmembrane components of the envelope protein gp41.

-Gp41 mediates fusion of the virus envelope with the host cell membrane

38
Q

HIV-1 infection cycle

A

1) HIV-virion binds via chemokie receptor
2) fusion occurs
3) reverse transcription of viral RNA genome occurs
4) integration into hosts chromosomal DNA
5) expression and translation
6) synthesis of viral core proteins and reverse transcriptase in the cytoplasm
7) synthesis of gp12 and gp41 in the ER and membrane budding
7) assembly
8) budding
9) maturation
10) new HIV virion

39
Q

dendritic cells translocate HIV from mucosa within

A

30 mins of infection

40
Q

immunological consequence of HIV infection

A
  • o A wave of viral proliferation in lymph nodes peaks at 4-7 days after infection
    o Viremia peaks at 14 days and all lymphoid tissues are infected by 3 weeks
    o HIV is quiescent in resting CD4 T cells, but on T cell activation, virus production is also activated and the host cell dies
41
Q

> 99% of virus is produced by

A

newly infected CD4 T cells

42
Q

around how many CD4 T cell ar producing virus at any time

A

10^7- 10^8 CD4 T cells

43
Q

consequence of CD4 T cells being affected

A

o loss of helper activities (mainly through cytokine stimulation) means that maintenance of cytotoxic CD8 T Cells is lost as is the antibody response of B cells

44
Q

progression of untreated HIV infection

A
  • flu like illness from days to weeks after exposure
  • CD4- dependent antiviral cytotoxic CD9 T cell response develops and is responsible for prolonged period of stable viremia- viral set point
  • patients ar normally asymptomatic until the CD4 T cell counts define further- infection of developing lymphocytes in the bone marrow and thymus results in failure to replace lost Tcells
  • opportunist infections begin when CD4 T cell count reaches below 200/ul
45
Q

flu like symptoms are a result of

A

drop of CD4 T cells

46
Q

viral set point

A

CD4- dependent antiviral cytotoxic CD9 T cell response develops and is responsible for prolonged period of stable viremia

47
Q

when do opportunistic infections arise

A
  • when CD4 T cell count reaches levels below 200/ul
48
Q

death typically ensues around

A

2 years later without treatment

CBI - UOE (61 decks)

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