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HIV Flashcards

1
Q

Classification of Retroviruses

A
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2
Q

Simple retroviruses encode

A

gag, pol, and env genes

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3
Q

Complex viruses also encode

A

accessory genes (HIV: tat, rev, nef, vif, vpu)

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4
Q

slow viruses assoc. with neurologic and immunosuppressive disease

A

Lentiviruses

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5
Q

Gag

A

group-specific antigen (core and capsid proteins)

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6
Q

Pol

A

polymerase (reverse transcriptase, protease and integrase)

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7
Q

Env

A

envelope (glycoproteins)

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8
Q

HIV characteristics

A

RNA Viruses, ss, (+) sense, RT

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9
Q

HIV pic

A
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10
Q

4 accessory genes HIV

A

(vif, vpr, vpu, nef)

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11
Q

2 regulatory genes (virus-host interactions) HIV

A

tat

rev

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12
Q

Binding and Fusion HIV characteristics

A

begins by binding to a CD4 receptor and co-receptor on the surface of a CD4+ T-lymphocyte fuses with the host cell releases RNA into host cell

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13
Q

Integration HIV

A

Newly formed HIV DNA enters the host cell’s nucleus

→ HIV integrase helps insert the HIV DNA within the host cell’s own DNA

integrated HIV DNA: provirus

→ The provirus may remain inactive for several years, producing few / no new copies of HIV

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14
Q

Transcription HIV

A

Host cell receives a signal to become active provirus uses a host RNA polymerase to copy the HIV genomic material and mRNA

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15
Q

Assembly HIV

A

HIV protease “cuts” the long chains of HIV proteins into smaller individual proteins (smaller HIV proteins assemble with copies of HIV genome  new virus particle)

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16
Q

Budding HIV

A

Newly assembled virus buds from the host cell

  • takes part of the cell’s outer envelope (is studded with HIV glycoproteins)
  • HIV glycoproteins: necessary for virus to bind CD4 and co-receptors, allowing them to move on to infect other cells
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17
Q

Which HIV subtype is found in the US

A

HIV-B

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18
Q

HIV replication cycle

A
  1. Fusion
  2. Entry
  3. Viral DNA via RT
  4. Viral DNA: transport to nucleus, integration 5. New vRNA  genomic RNA, viral proteins
  5. New vRNA + proteins move to cell surface  new, immature, HIV virus
  6. Virus matures by protease releasing individual HIV proteins
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19
Q

HIV – Transmission

A

• Infected individual’s blood, semen or vaginal fluid

– Unprotected anal, vaginal, oral sex w/ infected individuals

– Share needles / syringes w/ infected individuals

  • Increased risk with other STI infections
  • HIV does not survive for long periods of time outside host
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20
Q

characteristics of newly infected HIV pts

A

 About 97% are in low and middle income countries

 About 1000 are in children under 15 years of age

 About 6000 are in adults aged 15 years and older, of whom:

─ almost 48% are among women

─ about 42% are among young people (15-24)

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21
Q

HIV – Pathogenesis

A

virus tropism for CD4- expressing T cells and macrophage lineage cells

– multipotent hematopoietic stem and progenitor cells

Dendritic cells

– Accumulate the virus particles on their surfaces, but do not usually internalize them

– carry virus to lymph nodes resulting in efficient infection of CD4+ T cells

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22
Q

Mechanisms of immune evasion HIV

A

– antigenic variation

– carbohydrate masking of target epitopes

– conformational changes

by viral envelope to mask neutralization targets

– downregulation of host HLA

– viral latency in resting T cells and antigen- presenting cells

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23
Q

HIV encephalopathy CPEs

A

Cells appear to be the result of syncytial fusion of HIV-infected macrophages and microglia

Virus spread  cell to cell; immune circulatory antibodies cannot have an effect

Syncytia often seen in the brain

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24
Q

HIV - Diagnosis methods

A

Antibody or antigen testing (usually within a few weeks of infection), ELISA / Western Blot

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25
Q

After CDC reccomendations, how much of a reduction in AIDS was seen over years

A

95% rate drop

26
Q

Mortality and highly active antiretroviral therapy (HAART) use

A

Significant drops in HIV deaths

27
Q

Percentage of people eligible who are receiving antiretroviral therapy highest in what nations

A

Latin america

28
Q

Course of HIV Progression

Typical/rapid/ nonprogression

A
  • Typical progression – 80%, 7-10 yrs
  • Rapid progression – 5-10%, within 2 yrs
  • Non-progression

– 10-15%, no disease ~7-10+ yrs

– CD4 count stays high, viral load not detectable (no medications)

29
Q

Course of HIV Progression graph

A

• Window period

– Negative HIV test (primary infection to sero- conversion)

– Viral load very high,  high transmission risk

• Acute retroviral syndrome

– Symptoms can have a huge range – WIDE DIFFERENTIAL DIAGNOSIS

• Opportunistic infections

– GOAL is to prevent these from occurring – Greatly increase chance of death

30
Q

Acquired Immunodeficiency Syndrome (AIDS)

A

• final stage of HIV infection

– virus has weakened the immune system to the point at which the body has a difficult time fighting infection

31
Q

Progression of AIDS

A

1) acute infection
2) strong anti-HIV immune defense
3) a latent reservoir
4) loss of CD4+ cells and loss of immune response
5) onset of AIDS

32
Q

Bacterial pneumonia in AIDS cause

A

Common cause is Streptococcus pneumoniae

33
Q

Streptococcus pneumoniae, Virulence

A

colonize oropharynx (surface protein adhesions),

spread into normally sterile tissues

(pneumolysin, IgA protease), stimulate

local inflammatory response (teichoic acid, peptidoglycan fragments, pneumolysin), and evade phagocytic killing (polysaccharide capsule)

34
Q

Mycobacterium avium complex (MAC) in AIDS

CD4 count?

species?

A

CD4 <50

M. avium and M. intracellulare

35
Q

Mycobacterium avium complex characteristics

A

Weakly Gram +, strongly acid-fast aerobic rods

• Disease: host response to infection

– asymptomatic colonization, chronic localized pulmonary disease, solitary nodule

– disseminated disease (particularly in patients w/ AIDS)

• Tissues can be filled w/ Mycobacteria; 100s – 1000s

bacteria / ml of blood

36
Q

Mycobacterium avium complex infection types/progess

A

(1) pulmonary MAC: immunocompetent hosts
(2) disseminated MAC: individuals w/ advanced AIDS
(3) MAC lymphadenitis in children

37
Q

leading cause of death among people living with AIDS

A

Tuberculosis (TB)

– common opportunistic infection associated w/ HIV

38
Q

infection pretty common in HIV + people

A

Salmonellosis

39
Q

Bartonella henselae characteristics

A

(Gram – rod)

– Bacillary angiomatosis: vascular proliferative

disease in immunocompromised patients

– Infection primarily involves skin, lymph nodes, or liver and spleen

– Subacute endocarditis

– Cat-scratch disease: chronic regional lymphadenopathy assoc. w/ cat scratch

40
Q

Bacillary angiomatosis

A

appears as purplish to bright red skin patches, often resembling Kaposi’s sarcoma

Bacillary angiomatosis:

reactive vascular proliferation

secondary to infection by

Bartonella henselae

41
Q

HIV infection + hepatitis, -> more likely to develop

A

liver toxicity from medications

42
Q

most common viral

cause of congenital defects

A

CMV

43
Q

CMV Establishes latent infection in

A

mononuclear lymphocytes, stromal cells of bone marrow

44
Q

CMV member of

A

Member of Betaherpesvirinae,

45
Q

CMV damages

A

Weakened immune system: virus can cause damage to eyes through infection and inflammation

  • retina (CMV retinitis, untreated leads to blindness)
  • digestive tract
  • lungs or other organs
46
Q

Human Herpesvirus (HHV-1 and -2) in AIDS patients

A

– HIV increases the probability that infection is more severe, sores may take longer to heal, systemic symptoms may also be more severe (may cause brain damage and blindness)

– Immunocompromised people and neonates are at risk for disseminated, life-threatening disease

47
Q

Human Papillomavirus (HPV) in AIDS

A

– Infection w/ both HPV and HIV increases a woman’s risk even further: cervical cancer occurs more often, more aggressively in women who are HIV-positive

48
Q

Progressive multifocal leukoencephalopathy (PML)/ JC virus

A

Serious brain infection caused by the human polyomavirus JC virus

  • speech problems
  • weakness on one side of the body • loss of vision in one eye
  • numbness in one arm or leg

– PML usually occurs only when the immune system has been severely damaged

49
Q

Progressive multifocal leukoencephalopathy

A

grossly as irregular areas of granularity in white matter, which bear some resemblance to the plaques of

demyelination with multiple sclerosis

50
Q

Kaposi’s sarcoma, HHV-8 (KSHV) characteristics

A

– Tumor of the blood vessel walls

– Rare in people not infected with HIV

– Usually appears as pink, red or purple lesions on the skin and mouth (with darker skin, the lesions may look dark brown or black)

51
Q

THE MOST FREQUENTLY DETECTED TUMORS IN AIDS PATIENTS

A

Kaposi’s sarcoma, HHV-8 (KSHV)

52
Q

Non-Hodgkin’s lymphoma: most common w/

A

inherited immune

deficiency, autoimmune disease, or HIV

53
Q

Viral infections: HTLV-1, Hep C, and EBV, ↑ risk of

A

developing

non-Hodgkin’s lymphoma

54
Q

Fungi that leads to pneumonia in aids patients

A

Candidiasis

55
Q

common central nervous system infection

associated with HIV

A

Cryptococcal meningitis

56
Q

– caused by a fungus that is present in soil or associated with bird or bat droppings

– does not seem to spread person to person

A

Cryptococcal meningitis

57
Q

Cryptococcal meningitis CD4 count

A

CD4 cell counts are below 100

58
Q

Major virulence factors Cryptococcus neoformans

A

polysaccharide capsule, phenol oxidase enzyme, ability to grow at 37°C

59
Q

Pneumocystis jirovecii (formerly P. carinii, PCP)

A

– Previously considered to be a protozoan parasite

– Infection almost exclusively in debilitated and immunosupressed patients

60
Q

Toxoplasmosis

A

parasite spread primarily by cats

  • humans can contract by touching their mouths with their hands after changing cat litter
  • eating raw or undercooked meat, especially pork, lamb and venison

– Leads to encephalitis in many patients with AIDS

61
Q

Cryptosporidiosis

A

– Infection → intestinal parasite commonly found in animals (ingestion of contaminated food, water)

– Leads to severe, chronic diarrhea in people w/ AIDS

self-limited syndrome in HIV-infected individuals w/ CD4 counts > 200, disease refractory to therapy in individuals w/ suppressed CD4 counts

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