Introduction to Viruses Flashcards

1
Q

Describe the possible shapes of a virus

A

Icosahedral : 20 faces, each an equilateral triangle
Helical: Protein binds around DNA/RNA in a helical fashion

Complex: Neither helical or icosahedral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are obligate intracellular pathogens?

A

Can only replicate inside a host cell

Viruses are these

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What can virus families be classified according to?

A

Virion shape / Symmetry
Presence or absence of envelope
Genome structure
Mode of replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define virion

A

The complete, infective form of a virus, outside its host cell, with a core RNA and a capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What encapsulates the nucleic acid of a virus?

A

A protein capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What surrounds the protein capsid?

A

A lipid envelope containing spike projections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the stages of virus replication?

A

Attachment
Uncoating
Replication of genomic nucleic acid
Protein synthesis
Virion assembly (insertion of virus proteins into a membrane)
Budding and release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the methods of viral transmission?

A

Blood bourne
Sexual
Vertical
Faecal - oral
Droplet
Airborne
Close contact
Vector-borne (indirect transmission of an infectious agent - occurs when a vector bites or touches a person
Zoonotic ( a disease that normally exists in animals but can infect humans)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What might the coinfection of human and animal or bird strains in one organism lead to?

A

Recombination and generation of a new strain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the syndromes associated with viral infections?

A

Respiratory
Neurological
Gastroenteritis
Hepatitis
Skin infections
Eye infections
Congenital abnormalities
Arthralgia - infection of a joint
Lymphadenopathy (disease affecting the lymph nodes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the consequences of viral infection?

A

No, short or long lasting immunity

Chronic infection

Latent infection (lysogenic part of the cell cycle - lies dormant)

Transformation - long term infection with altered cellular gene expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the status of the viral genome during latency

A

Retained in host cell - expression is restricted (produces few antigen and no viral particles are produced)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What can does reactivation cause?

A

May or may not cause disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When is reactivation most likely to occur?

A

In the immunocompromisd - also where it is most severe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can some viral infections lead to cancer?

A

Modulation of cel cycle control - driving cell proliferation
Modulation of apoptosis - preventing programmed cell death
Reactive oxygen species mediated damage - infections can cause persistant inflammatory processes which lead to cancer via reactive oxygen species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the three aspects of a virus that you can detect?

A

The whole organism - microscopy, part of the organism (antigen, nucleic acid - PCR (extraction of genetic material followed by amplification of a specific region) -
or the immune response to a pathogen (used to determine a recent infection, prior infection or a response to vaccination)

17
Q

What is common in all antiviral agents?

A

They are virustatic none are virucidal. This means they only inhibit the growth of the virus, stops the virus replicating

18
Q

Why are their limited target proteins for antiviral drugs?

A

Virus utilises host cell enzymes in order to replicate

19
Q

Give a reason why antiviral therapy is not used very commonly

A

Toxicity to the host cell is not uncommon

20
Q

Give examples of when antiviral therapy may be used

A

Prophyaxis (prevents infection)

Pre-emptive therapy (when evidence of infection is detected but symptoms are not yet apparent)

Overt disease

Suppressive therapy - keeps viral replication below the rate that causes tissue damage in asymptomatic infected patient, common in long term immunodeficiency patients.

21
Q

What are the possible methods of prevention of viral infections?

A

Immunisation (vaccination - active and passive)
Prophylactic treatment post exposure
Infection prevention and control measures (isolation of symptomatic patients, PPE, Safe disposal of sharps)
Screening - blood, tissue s and organs
Antenatal screening

22
Q

When can viruses be eradicated?

A

No animal reservoir or ability to amplify in the environment
Clearly identifiable in diagnosis
No chronic state carrier (so you don’t miss those who are infected)
Efficient and practical intervention
Political and social support