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Principles of Disease > Introduction to Viruses > Flashcards

Introduction to Viruses Flashcards

1
Q

What three categories can viruses be placed into

A

Icosahedral - have 20 faces with each being an equilateral
Helical - the protein binds around DNA/RNA in a helical fashion
Complex - neither icosahedral or helical

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2
Q

Where do viruses replicate

A

Inside the host cell as they are obligate intracellular pathogens

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3
Q

Viruses are…

A

non-cellular and small

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4
Q

How can viruses be classified

A 
Order
Family
Genus
Species
(in this order)
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5
Q

What factors are looked at when determining virus families

A

Virion shape/symmetry
Presence/absence of envelope
Genome structure
Mode of replication

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6
Q

Describe the structure of viruses

A 
They have:
Spike projections
Lipid envelope
Protein caspid
Virion associated polymerase
Nucleic acid
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7
Q

How do viruses replicate

A 
The viruses undergoes:
Maturation
Attachment
Uncoating
Replication of genomic nucleic acid (either through mRNA synthesis or genomic nucleic acid synthesis)
Protein synthesis
Virus proteins are inserted into the membrane
Virion is assembled
Budding and release
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8
Q

What is host range in viruses

A

Some viruses may only infect humans while others can also infect other animals/birds

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9
Q

What can the coinfection of human and animal/bird strains in one organism cause

A

The recombination and generation of a new strain

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10
Q

What can a viral infection cause

A

Clearance of a virus with: no, short or long-term immunity
Chronic infection (e.g. HIV, Hep B)
Latent infection
Transformation

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11
Q

What is transformation

A

Long-term infection with altered cellular gene expression (e.g. EBV)

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12
Q

Give an example of a disease which shows viral latency

A

Herpes Simplex Virus

Varicella Zoster Virus

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13
Q

What is viral latency

A

When viruses stay dormant in the host cell after a primary infection.
The full viral genome is present but its expression is restricted

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14
Q

What is reduced in viral latency

A

Number of viral antigens present

No viral particles produced

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15
Q

Where is reactivation most likely to occur

A

Immunocompromised patients

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16
Q

How can viruses lead to cancer

A

By:
Modulation of cell cycle control - to drive cell proliferation
Modulation of apoptosis - prevents apoptosis
Reactive oxygen species mediated damage - some persistent viral infections can cause persistent inflammatory processes which lead to cancer via reactive oxygen species

17
Q

Give examples of viruses which can lead to cancer

A

EBV - leading to Hodgkin’s lymphoma, nasopharyngeal carcinoma and post-transplant lymphoproliferative disease
Human herpes virus 8 - leading to Kaposi’s sarcoma, primary effusion lymphoma, Castlemans’s disease
HPV - cervical, anal oropharyngeal cancers

18
Q

What parts of a virus can be dectected

A

Whole organism
Part of organism (e.g. antigen, nucleic acid)
Immune response to a pathogen (e.g. antibodies)

19
Q

How can the whole viral organism be detected

A

Microscopy

Culture

20
Q

How can part of the viral organism be detected

A

Antigen dectection
DNA/RNA dectection
Extraction of genetic material from sample
Amplification of region of target organism genome

21
Q

What can an immune response be used to determine

A

An acute/recent infection

Prior infection/response to vaccination

22
Q

Are antiviral agents virustatic or virucidal

A

Virustatic

23
Q

When is antiviral therapy used

A

Prophylaxis - to prevent infection
Pre-emptive therapy -
when there is evidence of infection/replication but before symptoms begin
Overt disease
Suppressive therapy - to keep viral replication below the rate which causes tissue damage in an asymptomatic infected

24
Q

How can viral infections be prevented

A 
Vaccinations
Passive immunisation with immunoglobulin
Prophylactic treatment post exposure
Infection prevention and control measures
Blood/tissue/organ screening
Antenatal screening
25
Q

What infection prevention and control measure can be put into place

A

Isolation of symptomatic patients
Personal protective equipment
Safe use and disposal of sharps

26
Q

Give examples of viruses which can be eradicated

A

Small pox (eradicated in 1979)
Measles
Polio

27
Q

What properties do viruses require to potentially be eradicated

A

They should:
Have no animal reservoir or ability to amplify in the environment
Be clearly identifiable, with accurate diagnostic tools
Have no chronic carrier state
Have efficient and practical intervention, e.g. vaccination
Have political/social support

28
Q

How are viruses classified

A

Shape
Presence of envelope
Genome structure
Mode of replication

29
Q

What cancer is hepatitis B associated with

A

Hepatocelluar carcinoma

30
Q

What is S. aureus common cause of

A

Skin and soft tissue infections

31
Q

What is group A strep

A

Beta haemolytic

32
Q

What is enterococcus faecalis

A

Gram positive cocci

Principles of Disease (41 decks)

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