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Microbiology > Chapter 38 - HIV > Flashcards

Chapter 38 - HIV Flashcards

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Biology 101 flashcards
1
Q

describe retroviruses

A
  • positive strand RNA viruses
  • enveloped
  • contain reverse transcriptase enzyme
  • cause chronic disease long after infection
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2
Q

HIV is a _____ that causes _____

A

retrovirus; AIDS

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3
Q

how do retroviruses cause chronic disease long after infection

A

integration of viral DNA into host chromosome

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4
Q

describe HIV adsorption and penetration during initial infection and later during infection

A
  • initial: M tropic: cells of macrophage lineage. receptor/coreceptor: CD4 and CCR5
  • later: T tropic: T cells, receptor/coreceptor: CD4 and CXCR4
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5
Q

describe target cell binding of HIV

A
  • viral ENV protein gp120 binds to cellular receptor CD4 and to coreceptor CXCR4 or CCR5
  • coreceptor interaction essential for gp41 contact and viral fusion with host cell
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6
Q

how can people be resistant to HIV

A

they lack the receptors necessary for fusion

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7
Q

what is HIV penetration due to

A

membrane fusion promoted by gp41

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8
Q

describe HIV genome replication

A
  • reverse transcriptase synthesizes one strand of DNA using viral RNA as the template
  • reverse transcriptase synthesizes the other strand of DNA using the newly created viral single DNA strand
  • cellular tRNA used as a primer by reverse transcriptase
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9
Q

what is the major target for anti HIV drugs

A

RT enzyme

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10
Q

RT enzyme is _____

A

error prone

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11
Q

what is the integration of viral DNA copy into host cell genome promoted by

A

viral integrase enzyme

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12
Q

Viral DNA is transcribed into RNA by ______

A

host cell RNA polymerase II

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13
Q

what are the steps in HIV genome replication

A
  • synthesis of viral DNA copy
  • integration of viral DNA copy into host cell genome
  • transcription of integrated viral DNA copy to create more viral RNA
  • HIV protein expression and viral assembly
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14
Q

describe HIV protein expression and viral assembly

A
  • viral RNA serves as mRNA for translation
  • viral RNA serves as the viral genome that is packaged into virions
  • viral assembly occurs at the plasma membrane
  • virions acquire their membrane by budding of nucleocapsids from the plasma membrane
  • translation creates vrial polyproteins
  • viral polyproteins get cleaved to final mature sizes by viral protease
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15
Q

what are the HIV accessory factors and what do they do

A
  • nef: decreases expression of MHC class I molecules on the surface of an infected cell, preventing killing by cytotoxic T cells
  • vpu: reduces cell surface CD4 expression and enhances viral release
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16
Q

what are long terminal repeats

A
  • transcriptional promotor (upstream LTR) and terminator (downstream LTR)
  • promotor responds to host cell signals and can also be relatively dormant, creating the latent state which is an inmportatn characterisitic of HIV
17
Q

what is AIDS caused by

A
  • HIV -1 (mainly): from Chimpanzee
  • HIV2: from sooty mangabey virus
18
Q

how can HIV enter body

A

-microabrasions on mucosal surfaces
- needle punctures
-intact mucosal surfaces

19
Q

HIV virus may enter as:

A

part of an infected cell- macrophage, lymphocyte, spermatozoa
- free virus

20
Q

what type of virus is AIDS

A

retrovirus

21
Q

what is initial contact of HIV mediated by

A

macrophage lineage cells
- infect/stick to dendritic cells
- transport to lymph node and contact CD4 T cells

22
Q

what is DTH reactions important for and what is it mediated by

A

important for controlling fungal and intracellular pathogens
- DTH is medaited by CD4T cells

23
Q

what are the neurological symptoms fo HIV caused by

A
  • not well understood
  • possibly viral infection of neurons
  • possibly release of substances by other cells that promote inflammation in the brain
24
Q

what is the relationship between CD4T cells and amount of virus in the blood

A

direct

25
Q

what are AIDS indicator conditions

A
  • candidiasis of the bronchi, trachea or lungs
  • candidiasis, esophageal
  • kaopsi sarcoma
  • mycobacterum avium complex (MAC) or mycobacterium kasasii, disseminated or extrapulmonary
  • mycobacterium tuberculosis
  • mycobacterium
  • pneumocystitis jiroveci pneumonia
26
Q

what is the transmission of HIV

A

by direct exposure of the persons bloodstream to body fluid containing virus

27
Q

where is HIV found in someone who is infected with the virus

A
  • blood
    -semen
  • vaginal fluid
28
Q

HIV is not transmitted by ______

A

casual contact like sneezing, kissing, bug bites

29
Q

transmission of HIV even through needlestick is ______. less than _____ of exposures show seroconversion

A

poor; 1%

30
Q

what is AIDS

A

progressive destruction of CD4+ cells elads to collapse of immune system

31
Q

what is an AIDS patient suscpetible to

A

opportunistic pathogens

32
Q

what central nervous system disease is also associated with AIDS

A

dementia

33
Q

what are AIDS related cancers

A

Kaposis sarcoma caused by human herpes virus 8

34
Q

what are the treatments for AIDS

A

-nucleoside analogue reverse transcriptase inhibitors
- nonnucleoside RT inhibitors
- protease inhibitors
- fusion penetration inhibitors

35
Q

is there a vaccine for AIDS

A

no

36
Q

what are other human retroviruses

A
  • Human T cell lymphotrophic viruses I, II, III, and IV
37
Q

what does HTLV I cause

A

adult T cell leukemia and lymphoma

38
Q

what does HTLV II, III and IV cause

A

no known diseases associated with these viruses

Microbiology (39 decks)

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