Introduction to Viruses 1 Flashcards
<p>What can you say about the size of viruses?</p>
<p>They are very small, being only 20-400nm in diameter</p>
<p>What can you say about cells, viruses and replication?</p>
<p>Viruses are non-cellular so genetic elements cannot replicate independent of a host</p>
<p>What are different structures of viruses?</p>
<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>
<p>What can you say about the host range of viruses?</p>
<p>Many viruses have a specific host range and can only infect specific host cell types</p>
<p>Can viruses be grown in a lab dish?</p>
<p>No, because they need a cell to act as a host</p>
<p>What are examples of icosahedral viruses?</p>
<p>Polio</p>
<p>Rhino</p>
<p>Adeno</p>
<p>What is an example of a helical virus?</p>
<p>Tobaccomosaic virus</p>
<p>What is a virus?</p>
<p>Genetic element that cannot replicate independently of a living (host) cell</p>
<p>What is virology?</p>
<p>The study of viruses</p>
<p>What is a virion?</p>
<p>Extracellular form of a virus</p>
<p>Where do virions exist and what do they do?</p>
<p>They exist outside of the host and facilitates transmission from one host cell to another</p>
<p>What do virions contain?</p>
<p>Nucleic acid genome surrounded by a protein coat and in some cases other layers of material</p>
<p>What are virus families classified according to?</p>
<p>Virion shape/symmetry</p>
<p>Presence/absence of envelope</p>
<p>Genome structure</p>
<p>Mode of replication</p>
<p>What do envelopes do to a virus?</p>
<p>Makes them much more fragile, making them easier to kill and cannot survive outside the body for a long time</p>
<p>What are examples of enveloped viruses?</p>
<p>Flu</p>
<p>HIV</p>
<p>Hep C</p>
<p>Where are lipid envelopes stolen from?</p>
<p>The host cell the virion came out of</p>
<p>What is the process of virus replication?</p>
<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>
<p>What are different kinds of transmission?</p>
<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>
<p>What can you say about the kinds of animals viruses can infect?</p>
<p>Some viruses can only infect humans whereas some can infect a range of animals, leading to recombination and generation of new strains</p>
<p>What does viruses infecting many kinds of animals lead to?</p>
<p>Recombination and generation of new strains</p>
<p>What are the possible consequences of viral infection?</p>
<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>
<p>What happens when viruses lie dormant?</p>
<p>Full virus genome is retained in the host cell but expression is restricted, but reactivation may occur</p>
<p>What are examples of viruses that can lie dormant?</p>
<p>Herpes simplex virus</p>
<p>Varicella zooster virus</p>
<p>How can viruses lead to cancer?</p>
<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>
<p>What aspects of a virus can be detected?</p>
<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>
<p>What can the whole organism be detected by?</p>
<p>Microscopy</p>
<p>Culture</p>
<p>What is not really used anymore?</p>
<p>Electron microscopy and cell culture</p>
<p>Why is cell culture not practical?</p>
<p>Works well but has a large time lag</p>
<p>What can looking at the immune response determine?</p>
<p>Acute/recent infection</p>
<p>Prior infection/response to vaccination</p>
<p>What does virustatic mean?</p>
<p>Stopping the growth of viruses</p>
<p>What are all antiviral agents?</p>
<p>Virustatic</p>
<p>Why are there limited viral proteins for antiviral agents to target?</p>
<p>Because viruses utlilise a host cells enzymes</p>
<p>What may antiviral agents be used for?</p>
<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>
<p>What is prophyaxis?</p>
<p>To prevent infection</p>
<p>What is pre-emptive therapy?</p>
<p>When there is evidence of infection but before symptoms are present</p>
<p>How can viruses be prevented?</p>
<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>
<p>What is eradication?</p>
<p>Permanent reduction to 0 of worldwide incidences of infection</p>
<p>What properties do viruses need to have to be eradicated?</p>
<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>
<p>What is an example of a virus that has been eradicated?</p>
<p>Smallpox</p>
