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Divine infection > Key Viruses - Blood Borne > Flashcards

Key Viruses - Blood Borne Flashcards

1
Q

Which key viruses are ssRNA?

A 
HIV
Hepatitis C
Norovirus
Ebolavirus
Influenzae
Dengue fever
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2
Q

Which key viruses are dsDNA?

A
  • Adenovirus
  • Hepatitis B
  • Epstein-Barr virus
  • Herpes zoster
  • Herpes simplex
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3
Q

Key viruses with latency?

A
  • EBV
  • Herpes zoster
  • Herpes simplex
  • Adenovirus
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4
Q

List the 5 key Blood Borne Viruses

A
  • HIV
  • Hepatitis B
  • Hepatitis C
  • Epstein-Barr virus
  • Ebola virus
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5
Q

Describe structure of HIV?

A
  • Single stranded RNA retrovirus
  • Capsid = protein shell protects genome
  • Host-derived lipid membrane of envelop
  • Reverse transcriptase enzyme
  • Intergrase enzyme
  • Protease enzyme
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6
Q

How is HIV transmitted?

A

HIV transmission = contact of infected bodily fluids with mucosal tissue / blood / broken skin.

  • Sexual contact
  • transfusion
  • medical procedures
  • Perinatal transmission
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7
Q

HIV mode of infection

A

1) Virus binds to the CD4+ receptor on cell surface & fuses with cell
2) virus enters and empties content into cell (infection)
3) viral ssRNA converted to dsDNA by enzyme reverse transcriptase
4) viral DNA integrated into host DNA by enzyme integrase
5) viral DNA transcribed during transcription in cell cycle
6) Viral proteins produced and bud off
7) virus matures as protein chains cut by enzyme Protease

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8
Q

HIV virulence factors?

A
  • Retrovirus
  • Integrase & reverse transcriptase = can be integrated into host DNA
  • Lipid Membrane of envelop = host derived = recognised as self
  • capsid = protects viral genome
  • Targets & lyses T lymphocytes = causes immunosuppression
  • requires co-receptor binding
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9
Q

Conditions linked to HIV infections?

A

HIV leads do AIDS
Opportunistic infections due to immunosuppression

AIDs-defining illnesses — and their symptoms
> TB — Coughing, fatigue, weight loss
> Pneumocystis pneumonia (PCP) — high fever, cough, difficulty breathing
> Cryptococcal disease — pneumonia, brain swelling, skin infections and UTI
> Cytomegalovirus (CMV) — Difficulty with vision, pneumonia and gastroenteritis
> Cryptosporidiosis — severe diarrhoea, abdominal cramps

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10
Q

Investigations for HIV — Blood test — Serology

A

Serology = using a Current test to detects both HIV Antigen (Ag) and HIV Antibody (Ab)

  • HIV Antigen (Ag) = viral protein
  • HIV antibody (Ab) = an immunoglobulin; produced as an immune response to antigen

Relatively quick test = get results on the same day
Must wait 4 weeks after infection, to do the test to get a +ve result.
May get false negative result if test is performed too early (— wait 4 weeks)

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11
Q

Investigations for HIV — Blood test — PCR

A

Polymerase chain reaction = PCR

  • Detects HIV Nucleic acid
  • Highly sensitive = can detect very early infection
  • Expensive and Slow results (up to 1 week)
  • Used for follow-up test / treatment response test = monitor how infected patient is responding to treatment
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12
Q

Investigations for HIV — Rapid test

A

Detects HIV Antibody

  • Blood test (finger-prick)
  • oral (saliva)
  • In-Home tests
  • Postal testing

If -ve result = it is accurate
But May get false +ve result (confirm with serology if a positive result is given)

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13
Q

Medical strategies used to treat and reduce the prevalence of HIV —

A

> Anti-retrovirals (ARVs) — different ARVs target different things

> Vaccination = injection with dead or weakened harmless HIV virus. Antigens allow for production of complementary antibodies… However HIV has rapid mutation rate.

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14
Q

ARVs dosage?

A

ARVs — Give 3 —
- Nucleoside reverse transcriptase inhibitor (x2)

Plus one of the following:

  • Non-nucleoside reverse transcriptase inhibitor
  • Protease inhibitor
  • Integrase inhibitor & CCR5 (entry) inhibitor
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15
Q

Non-medical strategies used to treat and reduce HIV prevalence?

A
  • Inc. condom usage
  • Prevent vertical transmission (mother-to-child transmission)
  • Medical circumcision
  • Post-exposure prophylaxis (PEP)
  • Pre-exposure prophylaxis (PrEP)
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16
Q

Different things targeted by different types of ARVs?

A
  • Inhibits Binding and fusion = inhibit HIV binding to CD4+ molecule and fusing to the cell
  • Inhibits reverse transcriptase enzyme = ssRNA cant be converted to dsRNA
  • Inhibits DNA integrase enzyme = prevents viral DNA being incorporated into host DNA
  • Inhibits protease enzyme = prevents the protein chains in the new viral particle from being cut into individual proteins. Prevents viral maturation.
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17
Q

Describe the structure of Epstein-Barr virus?

A
  • Herpesviridae
  • dsDNA
  • nucleocapsid
  • lipid envelope
  • glycoproteins on surface (gp350, gp42)
  • tegument (a.k.a. Integumentary system = the organ system that protects the body from various kinds of damage, such as loss of water or abrasion from outside the body)
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18
Q

Epstein-Barr transmission?

A
  • Intimate sharing of saliva
  • sexual contact
  • Asymptomatic shedding (virus can be present and transmissible without showing any symptoms)
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19
Q

Epstein-Barr Mode of infection?

A
  • Replicates in orthopharyngeal epithelium

Co-receptor binding —
- viral gp350 glycoproteins on surface binds to CD21
receptors on host B cells
- viral gp42 glycoproteins binds to MHC class II

  • Integrase enzyme = Integrates into viral DNA into host DNA
  • Viral DNA transcribed and translated along with host DNA in host cell replication
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20
Q

Epstein-Barr virulence factors

A
  • integrase enzyme
  • glycoproteins co-receptor binding = able to specifically target B-cells
  • asymptomatic shedding = can exist without showing symptoms so not detected
  • capsid = protects Nucleic acid
  • latency = can infect re-currently
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21
Q

Conditions linked to Epstein-Barr infection?

A
  • Glandular fever (infectious mononucleosis) (a.k.a. Mono)
  • Burkitt lymphoma
  • cancer
  • Splenomegaly
  • lupus
22
Q

Investigations for Epstein-Barr?

A

Serology — test for EBV Antibody

23
Q

EBV treatments?

A

Supportive = deal with symptoms
- immune system usually deals with the infection itself

Specific = Acyclovir

24
Q

Describe structure of Ebolavirus?

A
  • ssRNA
  • filovirus
  • viral lipid envelope
  • cylindrical/tubular shape
  • nucleocapsid envelope
  • matrix
25
Q

Ebolavirus transmission?

A
  • direct contact with infected body fluids

- dead/slaughtered animals (bush meat)

26
Q

Ebola mode of infection?

A

Can infect a wide variety of cells, using different attachment mechanisms for each cell type, except for lymphocytes.

27
Q

Virulence factors Ebolavirus?

A
  • Nucleocapsid envelop = protects viral Nucleic acid
  • Matrix
  • Ebola VP35 protein =
    > Antagonises antiviral signaling pathways
    > Important for viral RNA synthesis (co-factor for RNA
    polymerase)
  • sGP = binds to receptors and inhibits early Neutrophils release
28
Q

Symptoms and conditions linked to ebolavirus?

A 
Flu-like illness
Vomiting
Diarrhoea
Shock
Headache/confusion
Rash
Bleeding (internal & out of mucousal membranes)
29
Q

Investigations of ebolavirus?

A
  • PCR = detect viral Nucleic acid
30
Q

Treatments for ebolavirus?

A

Supportive
- restore physiological conditions (e.g. temp, BP etc.)

Specific = currently under development

  • antivirals
  • vaccine
31
Q

Describe structure for Hepatitis B?

A
  • dsDNA

- enveloped

32
Q

How is Hepatitis B transmitted?

A
  • IV drug use
  • Blood transfusions
  • body fluids
  • needlestick injuries (most common in HCW)
  • sexual contact
  • prenatal transmission

IVDU & HCW most at risk

33
Q

Hepatitis B mode of infection?

A

Incubation period = 6 weeks to 6 months

  • Replication specifically in hepatocytes
  • (hepatotropic)- Destruction of hepatocytes
34
Q

Hepatitis B virulence factors?

A

Antigens — target hepatocytes

  • HBsAg
  • HBcAg
35
Q

Symptoms and conditions linked to Acute Hepatitis B?

A
  • Liver cirrhosis / Jaundice / Fatigue
  • Abdominal pain / Nausea / Anorexia / Arthralgia (joint pain)

Majority feels symptoms. But very few cases can acc be asymptomatic.
Symptoms can take months after the exposure/infection to show symptoms

36
Q

Complications of acute Hepatitis B?

A

Complications =
— Up to 50% of cases = no/vague symptoms & clear infection
within 6 months
— < 1% = develop fulminant hepatic failure
— < 10% = develop chronic hepatitis (if infected as an adult)
— Up to 90% of cases = develop into chronic hepatitis (if infected as an infant)

37
Q

Serology of acute Hepatitis B?

A

Serology =
⇒Surface antigen, present within 6 weeks of infection (HBsAg). Rise in ALT / viral DNA
⇒ followed by Highly infectiouse-antigen (HBeAg)
⇒ Core antibody (IgM) is the first antibody to appear
⇒ e-antibody appears, disappearance of e-antigen, patient less infectious now (HBeAb)
⇒ Surface antibody appears last, clears virus and patient recovers (HBsAb)
⇒ Core antibody persists for life (IgG).

IgG = core antibody. usually after infection is cleared, usually persists for life. Can tell if person had infection before

38
Q

Investigations for acute Hepatitis B?

A

1) PCR = HBV DNA
2) HBV serology
3) Liver function tests (LFTs) ————>
- Bilirubin = Test liver’s ability to conjugate bilirubin

  • Liver transaminases = ALT & AST released when Hepatocyte damage/cellular integrity lost (key result = ALT/AST >1000)
    > Alanine transaminase (ALT)
    > Aspartate aminotransferase (AST)
  • Alkaline phosphatase (ALP) = elevated when there’s Biliary tract cell damage / cholestasis
  • Albumin = protein synthesised in the liver. Low albumin production = impaired liver function
  • Tests of coagulation = clotting factors are synthesised in liver. Impaired liver function Can result in excessive bleeding usually from GI tract. due to impaired production of clotting factors.
    > INR (International Normalised Ratio)
    > Prothrombin time (PT)
39
Q

Define and explain Chronic Hepatitis B infection?

A

Chronic Hep B = Hep B infection with persistence of the HBsAg after 6 months (virus not cleared)

  • 25% chronic infection leads to liver cirrhosis
  • ~5% will develop Hepatocellular carcinoma
40
Q

Status of HBsAg, HBcAb and HBsAb in different situations?

A

(Pg. 23 of ur personal infection notes (the table at the bottom))

41
Q

Investigations for chronic Hepatitis B?

A

Test for HBsAg antigen 6 months after infection
= positive result = chronic hep B
= means virus not cleared

42
Q

Treatment for Hepatitis B?

A

Acute = usually cleared by host immune system.
- if not cleared = chronic Hepatitis B

Chronic =
- No cure — virus integrates into host genome. So virtually impossible to get rid of.

  • Patient take life-long anti-virals required to suppress viral replication
  • Not required for everyone e.g. ‘inactive’ virus carrier (low VL / normal LFTs / no liver damage)

Prevention =

  • Vaccination
  • Chemoprophylaxis
43
Q

Describe the structure of Hepatitis C?

A
  • ssRNA
  • positive
  • lipid enveloped
  • icosahedral capsid
44
Q

Transmission of Hepatitis C?

A
  • IV drug use
  • Transfusions
  • Needlestick (HCW)
  • sexual contact
  • prenatal transmission
45
Q

Hepatitis C mode of infection?

A
  • Incubation period = 6 to 12 weeks

Hepatitis viruses
– Replication specifically in hepatocytes
(hepatotropic) – Destruction of hepatocytes

46
Q

Hepatitis C virulence factors?

A
  • destruction of hepatocytes
  • enveloped
  • capsid = protects Nucleic acid
  • frequent mutations
47
Q

Symptoms of Hepatitis C?

A

Symptoms =
- 80% cases have no symptoms (acute and chronic).
So hard to detect
- Remaining 20% have vague symptoms: Fatigue / Anorexia
Nausea / Abdominal pain (RUQ)

49
Q

Investigations for Hepatitis C?

A

Blood tests —
- Serology = anti-Hep C antibody, as it remains positive throughout life, even after clearance/cure (not protective, patients who previously cleared a Hep C infection can get reinfected)

  • Viral RT-PCR = if positive, this confirms on-going / chronic Hep C infection
50
Q

Treatment for Hepatitis C?

A

Treatment =
- No vaccine

… But there is a cure (directly acting antiviral drug combo)

  • Works in 8-12 weeks
  • > 90% effective cure
  • Costs 20-60 thousand pounds cost
  • Doesnt give future immunity as patient can get re-infected
51
Q

Serious Complications of Hepatitis C?

A
  • Liver failure (requiring liver transplant)
  • Liver cirrhosis
  • Jaundice
  • Hepatocellular carcinoma (primary liver cancer)
  • Decompensated liver disease

Divine infection (6 decks)

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