Introduction to Viruses 1

Question 1

<p>What can you say about the size of viruses?</p>

Answer 1

<p>They are very small, being only 20-400nm in diameter</p>

Question 2

<p>What can you say about cells, viruses and replication?</p>

Answer 2

<p>Viruses are non-cellular so genetic elements cannot replicate independent of a host</p>

Question 3

<p>What are different structures of viruses?</p>

Answer 3

<p>Icosahedral (20 faces, each in an equilateral triangle)</p>

<p>Helical (protein binds round DNA/RNA in a helical fashion)</p>

<p>Complex (neither of above)</p>

Question 4

<p>What can you say about the host range of viruses?</p>

Answer 4

<p>Many viruses have a specific host range and can only infect specific host cell types</p>

Question 5

<p>Can viruses be grown in a lab dish?</p>

Answer 5

<p>No, because they need a cell to act as a host</p>

Question 6

<p>What are examples of icosahedral viruses?</p>

Answer 6

<p>Polio</p>

<p>Rhino</p>

<p>Adeno</p>

Question 7

<p>What is an example of a helical virus?</p>

Answer 7

<p>Tobaccomosaic virus</p>

Question 8

<p>What is a virus?</p>

Answer 8

<p>Genetic element that cannot replicate independently of a living (host) cell</p>

Question 9

<p>What is virology?</p>

Answer 9

<p>The study of viruses</p>

Question 10

<p>What is a virion?</p>

Answer 10

<p>Extracellular form of a virus</p>

Question 11

<p>Where do virions exist and what do they do?</p>

Answer 11

<p>They exist outside of the host and facilitates transmission from one host cell to another</p>

Question 12

<p>What do virions contain?</p>

Answer 12

<p>Nucleic acid genome surrounded by a protein coat and in some cases other layers of material</p>

Question 13

<p>What are virus families classified according to?</p>

Answer 13

<p>Virion shape/symmetry</p>

<p>Presence/absence of envelope</p>

<p>Genome structure</p>

<p>Mode of replication</p>

Question 14

<p>What do envelopes do to a virus?</p>

Answer 14

<p>Makes them much more fragile, making them easier to kill and cannot survive outside the body for a long time</p>

Question 15

<p>What are examples of enveloped viruses?</p>

Answer 15

<p>Flu</p>

<p>HIV</p>

<p>Hep C</p>

Question 16

<p>Where are lipid envelopes stolen from?</p>

Answer 16

<p>The host cell the virion came out of</p>

Question 17

<p>What is the process of virus replication?</p>

Answer 17

<p>1) Replication of genomic nucleic acid</p>

<p>2) Virion assembly</p>

<p>3) Virion released from cell and attaches to another</p>

<p>4) Uncoats inside the other cell</p>

<p>5) Replication of genomic nucleic acid</p>

Question 18

<p>What are different kinds of transmission?</p>

Answer 18

<p>Blood borne</p>

<p>Sexual</p>

<p>Vertical</p>

<p>Faecal-oral</p>

<p>Droplet</p>

<p>Airborne</p>

<p>Close contact</p>

<p>Vector borne</p>

<p>Zoonotic</p>

Question 19

<p>What can you say about the kinds of animals viruses can infect?</p>

Answer 19

<p>Some viruses can only infect humans whereas some can infect a range of animals, leading to recombination and generation of new strains</p>

Question 20

<p>What does viruses infecting many kinds of animals lead to?</p>

Answer 20

<p>Recombination and generation of new strains</p>

Question 21

<p>What are the possible consequences of viral infection?</p>

Answer 21

<p>Clearance of virus (no short or long term immunity)</p>

<p>Chronic infection</p>

<p>Latent infection (virus lies dormant)</p>

<p>Transformation (long term infection with altered cellular gene expression)</p>

Question 22

<p>What happens when viruses lie dormant?</p>

Answer 22

<p>Full virus genome is retained in the host cell but expression is restricted, but reactivation may occur</p>

Question 23

<p>What are examples of viruses that can lie dormant?</p>

Answer 23

<p>Herpes simplex virus</p>

<p>Varicella zooster virus</p>

Question 24

<p>How can viruses lead to cancer?</p>

Answer 24

<p>Modulation of cell cycle control (driving cell proliferation)</p>

<p>Modulation of apoptosis (prevention of programmed cell death)</p>

<p>Reactive oxygen species damage (causes inflammatory response which lead to cancer via oxygen species)</p>

Question 25

<p>What aspects of a virus can be detected?</p>

Answer 25

<p>Whole organism</p>

<p>Part of organism (such as antigen or nucleic acid)</p>

<p>Immune response to a pathogen (such as an antibody)</p>

Question 26

<p>What can the whole organism be detected by?</p>

Answer 26

<p>Microscopy</p>

<p>Culture</p>

Question 27

<p>What is not really used anymore?</p>

Answer 27

<p>Electron microscopy and cell culture</p>

Question 28

<p>Why is cell culture not practical?</p>

Answer 28

<p>Works well but has a large time lag</p>

Question 29

<p>What can looking at the immune response determine?</p>

Answer 29

<p>Acute/recent infection</p>

<p>Prior infection/response to vaccination</p>

Question 30

<p>What does virustatic mean?</p>

Answer 30

<p>Stopping the growth of viruses</p>

Question 31

<p>What are all antiviral agents?</p>

Answer 31

<p>Virustatic</p>

Question 32

<p>Why are there limited viral proteins for antiviral agents to target?</p>

Answer 32

<p>Because viruses utlilise a host cells enzymes</p>

Question 33

<p>What may antiviral agents be used for?</p>

Answer 33

<p>Prophylaxis (to prevent infection)</p>

<p>Pre-emptive therapy (evidence of infection is detected but before symptoms are present)</p>

<p>Overt disease</p>

<p>Suppressive therapy (keep viral replication below the rate that causes tissue damage)</p>

Question 34

<p>What is prophyaxis?</p>

Answer 34

<p>To prevent infection</p>

Question 35

<p>What is pre-emptive therapy?</p>

Answer 35

<p>When there is evidence of infection but before symptoms are present</p>

Question 36

<p>How can viruses be prevented?</p>

Answer 36

<p>Immunisation (vaccination/passive immunisation with immunoglobin)</p>

<p>Prophylactic treatment post exposure</p>

<p>Infection prevention and control measures</p>

<p>Blood/tissue/organ screening</p>

<p>Antenatal screening</p>

Question 37

<p>What is eradication?</p>

Answer 37

<p>Permanent reduction to 0 of worldwide incidences of infection</p>

Question 38

<p>What properties do viruses need to have to be eradicated?</p>

Answer 38

<p>No animal reservoir or ability to amplify in the environment</p>

<p>Clearly identifiable</p>

<p>No chronic carrier state</p>

<p>Efficient and practical intervention (such as vaccination)</p>

<p>Political/social support</p>

Question 39

<p>What is an example of a virus that has been eradicated?</p>

Answer 39

<p>Smallpox</p>