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Semester 3 - Infection > Session 6 - Blood Borne Disease > Flashcards

Session 6 - Blood Borne Disease Flashcards

1
Q

6.1 Describe the principles of virus structure, classification and replication
What are the two main ways to categorise a virus?

A
  • Number of strands
    • DNA or RNA
    • Enveloped or non-enveloped
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2
Q

What is a virion

A

• Genome + Capsid of a virus

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3
Q

What are the four main types of virus?

A
  • Double stranded RNA -Rota virus
    • Single stranded RNA - HIV, HEP A,C + E, MMR
    • Double stranded DNA - Herpes, Hep B, HPV

Single stranded DNA - Parvo B 19

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4
Q

What is the process of virus infection and replication?

A 
All Emus Urinate To Scare Hairless Rabbits
• Adsorption 
	• Entry 
	• Uncoating 
	• Transcription 
	• Virion synthesis 
	• Assembly 
	• Release
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5
Q

What occurs in adsorption?

A

• The initial attachment of a virus involves an interaction between specific molecular structures on the virion surface and receptors (HIV CD4+ receptors)

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6
Q

What occurs in entry?

A

• Entry is the passage of the virion from the surface of the cell across the cell membrane and into the cytoplasm

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7
Q

Give two ways in which entry occurs

A
  • Receptor mediated endocytosis
    • Membrane fusion (enveloped viruses enter a host cell by fusion of their envelope with the plasma membrane of the cell)
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8
Q

What occurs in uncoating?

A

• Refers to the stepwise diassembly of the virion that enables the expression of the viral genes that carry out replication

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9
Q

What occurs in transcription?

A

• Viruses RNA transcribed into host DNA with reverse transcriptase

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10
Q

What occurs in Virion synthesis?

A

Genome is replicated

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11
Q

What occurs in assembly?

A

• Viruses are assembled ready for release

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12
Q

What occurs in release?

A

• Viruses are released extracellularly

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13
Q

What investigations can be used to detect a virus?

A
  • PCR (REVISE MGD) to amplify and detect virus DNA
    • ELISA for particular antigens - 25 days post infection minimum

Demonstration of immune response

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14
Q

What are the key principles of Blood Borne Viruses?

A
  • All transmitted via blood and sex
    • Often an asymptomatic period
    • Significant morbidity/mortality
    • Treatments include cure and suppression
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15
Q

How many people are infected with HIV across the world?

A

• 70 million (0.8% of adults worldwide)

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16
Q

Outline 6 ways in which HIV is transmitted

A
  • Sexual contact
    • Injecting drug use
    • Mother to infant

Blood/tissue products

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17
Q

Give the six steps of HIV infection

A
  • Attachment to host CD4 cell
    • Reverse transcriptase makes DNA from viruses RNA
    • Integration in host cells nucleus
    • Reproduction of viral components
    • Assembly of new HIV viruses

Release

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18
Q

What are the main stages of HIV infection?

A
  • Initial infection
    • Acute phase viremia
    • Latent period
    • AIDs

End stage AIDs

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19
Q

What happens in initial infection of HIV?

A

• Macrophages in genital tract pick up infection

Disseminate to T helper cells (CD4+)

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20
Q

What is the acute phase viremia of HIV?

A
  • 1/3 to 2/3 of people infected experience an acute disease

* Antibody can not be detected in blood until >10 weeks post infection

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21
Q

What is the latent period?

A
  • Virus replicate
    • CD4+ count slowly declines
    • Common opportunistic infections can become apparent (herpes)
22
Q

When does HIV becomes AIDs?

A

• When CD4+ count <200 microliters

23
Q

What are the main 6 symptoms of initial primary HIV

A
  • Fever
    • Rash
    • Flu-like illness
    • Weight loss
    • Pharyngitis

Lymphadenopathy

24
Q

What occurs as immune system is compromised in HIV infection?

A

• More and more infections become present

25
Q

What pieces of history should be gathered in order to gain a HIV diagnosis?

A
  • Symptoms
    • Past medical history
    • Drug history
    • Social history
    • Family history
26
Q

How is HIV diagnosed?

A
  • HIV 1&2 combined ab/ag test - What is the difference?
    • Immunoblot
    • HIV viral load
    • Resistance profile
    • CD4 levels
27
Q

What must be investigated in a HIV patient?

A
  • General organ system function
    • Status of HIV/immune system
    • Infections
    • Underlying co-morbidities
28
Q

Why treat HIV?

A
  • Prevent HIV related sdisease
    • Reduce morbidity and mortality
    • Improve life quality
    • Prevent resistance
    • Prevent transmission
29
Q

What are the two main clinical treatments for HIV?

A

• Multi-drug anti-retrovirals (HAART - Highly active antiretroviral therapy)

Antibiotic prophylaxis

30
Q

What is anti-retroviral treatment?

A
  • 3 drugs

* Affect different parts of life cycle

31
Q

Why is it important to catch HIV early?

A

• Adds years onto life expectancy

32
Q

Give some ways of reducing infection with HIV

A
  • Use condoms
    • Know sexual history of partners
    • No intravenous drug use/clean needles
    • Negative blood products
33
Q

Outline some ways of reducing HIV risk

A
  • Mother to child transmission reduced by detection
    • Circumcision
    • Pre-exposure prophylaxis
    • Post expose prophylaxis
    • Vaccination
34
Q

Why are researchers finding it difficult to find a cure for HIV?

A
  • Antigenically distinct versions appear across the word

* High rate of mutation

35
Q

What is hepatitis B?

A
  • Double stranded DNA virus

* Genotypes A-D

36
Q

How many people throughout the world are infected with Hep B?

A

350 million

37
Q

Outline four ways in which Hep B can spread

A
  • Heterosexual/homosexual intercourse
    • Injecting drug use

Body fluids - Breast milk

38
Q

What is the main pathogenesis of Hep B?

A
  • Infect differentiated hepatocytes

* Hepatocytes destroyed by cytotoxic T cells

39
Q

What is the disease progression of Hepatitis B

A
  • Acute infection
    • Chronic infection -> Cirrhosis
    • Cirrhosis -> Liver failure
    • Cirrhosis -> Liver cancer
    • Cirrhosis -> Liver transplant
40
Q

How can Hep B be staged?

A
  • Acute
    • Chronic
    • Past

Vaccinated?

41
Q

Outline some investigations for Hep B

A
  • General state
    • Liver function
    • Other BBV/STIs
    • Cancer screen
    • Image liver
    • Complications from liver damage
42
Q

What is an interesting symptom of cirrhosis?

A

• Oesophageal varices

43
Q

What four factors must be taken into account to decide treatment for Hep B?

A
  • Monitor viral load, liver function and complications
    • Decide when to give antivirals
    • Monitor antiviral side effects
    • Prevent other liver disease
44
Q

What treatments are used for Hep B?

A
  • Intreferon - Many side effects/high cost. No viral resistance.
    • Tenofovir - Potentail nephrotoxicity. First treatment in patients new to treatment.
45
Q

How can Hep B be prevented?

A
  • Vaccinated - Generalised, target
    • Safe sex
    • Mother to child interventions
    • Screening blood/products

Post exposure prophylaxis

46
Q

What mother=child interventions can be given to prevent transmission?

A
  • Lamivudine given, pregnancy safe drug

* Vaccine

47
Q

Categorise Hep C

A
  • Single stranded RNA
    • Flavivirus
    • Enveloped
48
Q

Is cure possible with Hep B?

A

No

49
Q

Is cure possible with Hep C?

A

• Yes

Combination drugs - Cure rate 40-80%

50
Q

What contributes to liver destruction in Hep C?

A

• Viral replication

Hosts immune cells

51
Q

How do people with Hep C often present?

A

• Acute hepatitis

Semester 3 - Infection (14 decks)

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