HIV Flashcards

1
Q

What is HIV

A

RNA retrovirus of the lentivirus genus

Causes acquired immunodeficiency syndrome (AIDS)

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2
Q

2 types of HIV

A

HIV-1: Type M and Type O

HIV-2

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3
Q

Epidemiology of HIV-2

A

predominantly confined to West Africa

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4
Q

Epidemiology of HIV-1 (type M and O)

A

Type M: prevalent in Europe, America, Australia and sub-Saharan Africa
Type O: mainly in Cameroon

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5
Q

Tramission

A

Unprotected sexual intercourse
Shared contaminated needles
Contaminated blood transfusions
Vertical transmission from mother to child. The virus crosses the placenta and is transmitted through breast milk

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6
Q

What is meant by vertical transmission in humans

A

From mother to child

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7
Q

Investigations

A
Bloods
Virology screen
Other infection e.g. TB if indicated
HIV specific tests:
-Enzyme-linked immunosorbent assay (ELISA)
-Western blot test
-Immunofluoresence assay (IFA)
-Nucleic acid testing
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8
Q

Blood investigations

A
FBC
U and Es
LFTs
Lipids
Glucose
HLA-B (5701 status)
Lymphocyte subsets
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9
Q

What is assessed on Virology screen for HIV

A
HIV antibody
HIV viral load
HIV genotype
Hepatitis serology
Cytomegalovirus antibody
Syphilis screen
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10
Q

Complications of HIV

A

Increased risk of opportunistic infections

Increased risk of malignancies

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11
Q

Examples of opportunistic infections that can result from HIV

A
Toxoplasma gondii
CMV e.g. retinitis
Pneumocystis jiroveci pneumonia
Cryptococcal meningitis
Mycobacterium avium complex
Candidiasis
Aspergillosis
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12
Q

Examples of malignancies that can result from HIV

A

Kaposi’s sarcoma
Non-Hodgkin’s lymphoma
Cervical cancer
Anal cancer

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13
Q

**HIV infection process

A

gp120 antigen on HIV binds to CD4+ receptors on the T cell
This process produces a conformational change and the need to bind to a co-receptor: CCR5 or CXCR4
gp41 binds to the co-receptor
This binding causes ‘six-helix bundle formation’ and fusion of the viral and host membranes
Disintegration of the viral capsid occurs causing viral RNA to be released into the human cell
Double-stranded RNA is produced and this process is catalysed by viral reverse transcriptase
Double-stranded RNA is integrated into host DNA using integrase enzyme
Host cell now manufactures new virions by long terminal repeat sequences and genes ‘tat’ and ‘rev’

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14
Q

What antigen on HIV binds to CD4+ receptors on T-cell

A

gp120

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15
Q

What antigen binds to CCR5 or CXCR4 coreceptor

A

gp41

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16
Q

What enzyme catalyses the production of double-stranded HIV RNA

A

viral Reverse Transcriptase

17
Q

What genes in infected host cell manufactures new virions

A

Long terminal repeat sequences

‘tat’ and ‘rev’ genes

18
Q

What enzyme integrates double-stranded RNA of HIV into the host DNA

A

Integrase

19
Q

What genes are required for viral replication

A

PEG:
pol - encodes reverse transcriptase and integrase
env - encodes envelope proteins e.g. gp120
gag - encodes biral structural proteins

20
Q

‘pol’ gene function

A

encodes reverse transcriptase and integrase

21
Q

‘env’ gene function

A

encodes envelope proteins e.g. gp120

22
Q

‘gag’ gene function

A

encodes viral structural proteins

23
Q

Conservative treatment

A

Patient education including transmission reduction advice
Contact tracing
Psychological support

24
Q

**Medical treatment

A

Highly active antiretroviral therapy (HAART):
2 x NRTIs combined with 1 x NNRTI
OR
2 x NRTIs combined with 1 x PI or 1 x II

NRTI = Nucleoside reverse transcriptase inhibitor
NNRTI = Non-nucleoside reverse transcriptase inhibitor
PI = Protease inhibitor
II = Integrase inhibitor
25
Q

Example of Nucleoside reverse transcriptase inhibitor (NRTI)

A

Zidovudine

26
Q

Example of Non-Nucleoside reverse transcriptase inhibitor (NNRTI)

A

Nevirapine

27
Q

Example of Protease inhibitor

A

Indinavir

28
Q

Example of Integrase inhibitor

A

Raltegravir