intro to viruses

Question 1

virion structural components

Answer 1

lipid envelope, nucleic acid, protein capsid, vision associated polymerase, spike projections (antigens)

Question 2

process of viral replication

Answer 2

attachment to host cell, uncaring, replication of viral genetics, protein synthesis, virion assembly, cell lyses to release new mature viral cell

Question 3

modes of transmission

Answer 3

blood-borne, sexual, vertical, faecal-oral, droplet, airborne, close contact, vector-borne, zoonotic

Question 4

consequences of viral infection

Answer 4

clearance of virus (resulting in no, short or long term immunity); chronic infection; latent infection; transformation (long term infection with altered cellular gene expression)

Question 5

describe viral latency

Answer 5

virus lays dormant in cell following primary infection; few or no viral particles are produced; reactivation MAY cause viral genome to express and cause illness (more likely to occur in the immunocompromised)

Question 6

describe the mechanisms of viral infection leading to cancer

Answer 6

• Modulation of cell cycle control (driving cell proliferation)
• Modulation of apoptosis (prevention of programmed cell death)
• Reactive oxygen species mediated damage

Question 7

features of antiviral therapy (3)

Answer 7

• all antiviral agents are virustatic, none are virucidal
• As viruses utilise host cell enzymes in order to replicate, there are limited viral proteins that are potential targets for antiviral drugs
• often toxic to host cell

Question 8

antiviral therapy may be used for… (4)

Answer 8

• prophylaxis
• pre-emptive therapy
• overt disease
• suppressive therapy

Question 9

methods of prevention of viral infection (5)

Answer 9

• immunisation (vaccination or passive)
• prophylactic treatment post exposure
• infection prevention and control
• screening
• antenatal screening

Question 10

properties that would potentially allow for the eradication of a virus (5)

Answer 10

• No animal reservoir or ability to amplify in the environment
• Clearly identifiable, with accurate diagnostic tool
• No chronic carrier state
• Efficient and practical intervention, e.g. vaccination
• Political / social support

Question 11

detection methods for whole organism (2)

Answer 11

• microscopy

- cultures

Question 12

detection methods for part of organism

Answer 12

-ELISA