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Immunology and Virology > Viruses > Flashcards

Viruses Flashcards

HIV, HSV-1, TBEV, dengue

1
Q

What are the two most common routes of transmission for HIV?

A

Blood and semen

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2
Q

Which family is HIV part of?

A

Retroviridae family

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3
Q

What was HIV previously known as and why?

A

GRID - Gay related infectious disease

Was seen in large numbers of gay men

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4
Q

How many people are infected with HIV worldwide each year?

A

36.9 million

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5
Q

How many people die from HIV related deaths each year worldwide?

A

1.2 million

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6
Q

Which genus is HIV part of?

A

Lentivirus

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7
Q

How many HIV virions can replication produce in a day?

A

10^10

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8
Q

How many groups does HIV-1 contain and what are they?

A

3 - M, N and O

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9
Q

There are two main types of HIV - what are they?

A

HIV-1 and HIV-2

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10
Q

Which HIV-1 group is the most prevalent?

A

M

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11
Q

How many subtypes does group M have?

A

8 subtypes

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12
Q

Which M group subtype is most commonly found in America and Europe?

A

Subtype B

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13
Q

Can HIV be transmitted through saliva?

A

No

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14
Q

How long can HIV survive in a reused needle?

A

42 days

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15
Q

What are three common routes of HIV transmission?

A

Blood, semen, pre-seminal fluid, vaginal fluid, rectal fluids, breast milk

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16
Q

Give an example of an activity where the risk of HIV transmission is high and explain why

A

Drug user sharing needles - HIV can survive on a reused needle for 42 days, penetrated into skin where it can reach the mucosal membrane
Rape victim - often violent which can create tears, allowing easier transmission into blood
Anal or vaginal sex
Birth - tears, damaged skin, lots of bodily fluids allowing risk for transmission/contact

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17
Q

Give an example of a less common route of HIV transmission

A

From mother to child during pregnancy
Birth
Breast feeding

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18
Q

Give an example of a lower risk route of HIV transmission

A 
Oral sex
Blood transfusions
Organ transplants
Bites
Pre-chewed foods
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19
Q

Give three features of stage 1 of HIV - acute infection

A

Single virion - 80% of mucosal infected individuals in B and C
Occurs around 10 days before vRNA is detectable
Within 2-4 weeks post infection may have flu-like symptoms that may last for a few weeks
Very infectious - virion production is at its highest
Asymptomatic

20
Q

What type of cell do HIV prefer to bind to?

A

CD4+ T cell

21
Q

At which stage of HIV infection is an individual most infectious?

A

Stage 1 - acute infection

Virion production is at its highest (plus individuals unlikely to know they’re infectious)

22
Q

What are the three stages of HIV infection?

A

Stage 1 - acute infection
Stage 2 - clinical latency
Stage 3 - AIDS

23
Q

What is stage 2 (clinical latency) of HIV infection?

A

Asymptomatic
Virus reproduces at lower levels (less infectious)
Viral load increases
CD4+ T cells decrease

24
Q

Roughly how long can a HIV +ve individual last in the clinical latency stage of infection with medication?

A

15+ years

25
Q

Roughly how long can a HIV +ve individual last in the clinical latency stage of infection without medication?

A

Around 10 years

26
Q

What is stage 3 (AIDS) of HIV infection?

A

Weakened immune system from reduced CD4+ T cells (now make up <14% of the total lymphocyte population)
Severe repeating illness, infections and opportunistic infections

27
Q

How long does a patient with AIDS typically survive?

A

3 years

28
Q

In AIDS, what percentage of the total lymphocyte population are CD4+ T cells?

A

<14%

29
Q

Give four symptoms of AIDS

A 
Fever
Chills
Diarrhoea
Fatigue
Weakness
Weight loss
Sweats
Swollen lymph glands
Blurred vision
Night sweats
Symptoms of recurrent, opportunistic infections: TB, pneumonia, fungal infections, HSV
30
Q

Which virus is the envelope protein Gp120 found on?

A

HIV

31
Q

What is the role of Gp120?

A

It is a docking glycoprotein found on the HIV envelope essential for virus entry.
Binds to CD4 and the co-receptor, inducing a conformational change to allow gp41 to penetrate the cell membrane

32
Q

What does HIV need to bind to on the host cell for viral entry?

A

CD4 and a co-receptor (either CXCR4 or CCR5)

33
Q

Which co-receptor used by HIV for viral entry is primarily found on CD4+ T cells?

A

CXCR4

34
Q

Which molecule is thought to be linked to HIV viral entry?

A

Cholesterol

35
Q

Describe the HIV lifecycle

A 
HIV receptor gp120 binds to CD4 and co-receptor (CCR5 or CXCR4). This causes a conformational change that allows gp41 transmembrane protein to penetrate the cell membrane.
The matrix and capsid protein are essentially digested, releasing the viral enzymes and RNA.
The viral RNA is reverse transcribed into viral DNA using host nucleotides. Reverse transcriptase can then do this again to produce dsDNA.
dsDNA forms a pre-integration complex (p17, integrate and VPR) which is transported to the nucleus
vDNA creates a circular long terminal repeat.
Viral integrase (p32) can then remove host chromosomal DNA and insert the vDNA
36
Q

The CD4 co-receptor CCR5 is primarily found on which cells?

A

T cells, macrophages, monocytes and DCs

37
Q

What is the viral protein p32?

A

Integrase (HIV)

38
Q

What are p16 and p14 (Tat)?

A

Transcriptional transactivators that bind to LTR

39
Q

How does HIV replicate?

A

p16 and p14 bind to LTR
p19 binds to vDNA and transports it to the cytoplasm
RNA polymerase II produces viral mRNA
Host ribosomes translate viral proteins (Tat, Rev, Gag and Env)
Env assembled in the golgi pathway and buds from host cell
As the virus buds from the host cell, it takes the lipid bilayer as the viral envelope
Virus inserts gp120 through the lipid bilayer

40
Q

Where is Env assembled in the HIV replication cycle?

A

Env is assembled in the golgi pathway (exact mechanism is unknown)

41
Q

What is the result when there is a switch from CCR5 to CXCR4 co-receptor binding?

A

Increased AIDS progression

42
Q

How long after peak viral load do T-cells to the original HIV virus peak?

A

1-2 weeks after peak viral laod

43
Q

What do T cells usually target in HIV infection?

A

Env (envelope protein), then Gag and Pol

44
Q

What is Gag (HIV)?

A

Capsid and matrix proteins

45
Q

What is Pol (HIV)?

A

Viral polymerase/enzymes

46
Q

In HIV infection, Abs generated targeted which viral proteins?

A

gp41 and gp120

Immunology and Virology (6 decks)

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