WEEK 8 Flashcards

Question

what does DdDP mean and do?

Answer 1

- for copying/replicating the DNA of a virus - DNA dependent DNA polymerase

Answer 2

- late mRNAs transported to cytoplasm for translation into structural proteins by host cell ribosomes - then later assembled into new virus particles (progeny)

Answer 3

- after viral DNA and proteins made, they are packaged together in defined sequence - usually occurs in the nucleus (could be cytoplasm)

Answer 4

- virions released by autolysis of the cell - budding and then exoctosis - sometimes apoptosis

Answer 5

1. Attachment of virus to specific receptors on host cell. 2. Penetration of the virus (or virus genome) into the cell. 3. Uncoating (removal of the virus protein coat and release of the viral genome). 4. Early transcription (not required with some virus types) and 5. translation of viral proteins (enzymes, etc., required for RNA replication). 6. Viral RNA synthesis 7. Late transcription (not required with some virus types) and 8. translation of viral proteins (structural proteins). 9. Assembly of the progeny virus particles. 10. Release of assembled virus particles.

Answer 6

- positive sense - negative sense - double-stranded RNA - retroviruses

Answer 7

- RdRp - for retroviruses, they use RT -> RNA-dependent DNA synthesis via reverse transcriptase (need to swap RNA to the complimentary first)

Answer 8

- host cells have DdRp - viruses must carry (encode in genome) RdRp

Answer 9

- can be directly translated into mRNA 1. RNA translated early into transcriptase and replicase enzymes 2. pos RNA forms intermediate neg sense template (complimentary), early enzymes used to form new viral pos RNA 3. pos sense RNA translated into late structural proteins and combined o make virions

Answer 10

- need to carry own RdRp in genome because neg is complimentary, not directly converted to correct strand (use intravirion polymerase) 1. neg RNA transcribed to pos mRNA by intravirion polymerase to make early viral proteins 2. neg sense converted to intermediate pos sense RNA (complimentary) by intravirion polymerase, produces neg sense RNA (progeny) 3. neg sense RNA converted to pos mRNA by intravirion polymerase and then late viral structural proteins made 4. all combined to make virions

Answer 11

1. dsRNA into mRNA by RdRp in cytoplasm 2. translation 3. RNA replication occurs inside icosahedral capsids with the help of RdRp they have

Answer 12

- they produce DNA from their RNA genome (use RT), his DNA is then incorporated into host cell genome (via integrase)

Answer 13

- genome is ssRNA pos sense. make a DNA intermediate 1. RT converts ss RNA to ss DNA (acts as RNA dependent DNA polymerase) 2. RT converts ss DNA to ds DNA (acts as DNA-dependent DNA polymerase) 3. use integrase to incorptorate DNA into host cell genome and cell will reproduce it for the virus - early and late phase proteins made + RNA 4. assembled

Answer 14

- RNA doesn't have a checking mechanism for its virions RNA so can't cause apoptosis on command. Instead usesonly cell lyses. - DNA can do either

Answer 15

*using flu example: - form proteins on capsid and then bud from cell and steal the membrane

Answer 16

- multiplicity of infection -> how many cells get infected per virus particle - if 1 virus introduced and 1 cell is infected, then = MOI1

Answer 17

susceptible cell: has a functional receptor for a given virus- the cell may or may not be able to support viral replication. resistant cell: has no receptor – it may or may not be competent to support viral replication permissive cell: has the capacity to replicate virus – it may or may not be susceptible BOTH: only cell that can take up a virus particle and can replicate it

Answer 18

viruses of the same species that are antigenically different.

Answer 19

- the purified virus attachment protein

Answer 20

an isolate whose genome sequence differs from that of a reference virus. No inference is made about whether the change in genome sequence causes any change in the phenotype of the virus.

Answer 21

A virus strain is a variant that possesses unique and stable phenotypic characteristics. Such characteristics can only be ascertained by the results of experiments done in the laboratory, in cells in culture and in animals, coupled with observations made in infected humans. The name strain is not easily earned: certainly it cannot simply be given by anybody.

Answer 22

Antigen (ag): a molecule capable of inducing an immune response (in this case a viral particle or viral component…usually protein) ▪ Could be detected before clinical symptoms appear Antibody (ab): a protein produced by the immune system when it detects (harmful) antigens (in this case viruses)... IgM, IgG, IgA, IgD, IgE ▪ Needs time to (5-14days) to develop ab

Answer 23

antigen: PCR, Ag-capture ELISA, TCID50, Plaque assay, Electron microscopy, VI (virus isolation) antibody: ELISA, VNT, HI, IHC

Answer 24

- tells us there was exposure in the past - can compare IgM vs IgG can tell you if recent infection has occurred

Answer 25

- every step of replication interacts with host cells and their cellular metabolism so hard to find substances that won't also harm the host - viral production is advanced by the time symptoms appear - viruses can't always be propagated so testing drugs is difficult

Answer 26

- antivirals - inhibit virus growth - immunoregulatory

Answer 27

Parenteral administration of neutralizing antibodies (e.g. monoclonal antibodies, hyperimmune serum), or oral administration of colostrum to a newborn animal are both methods of transferring passive immunity to the recipient. - gaining immunity via another source or past exposure - help identify and neutralise viruses (Y-shaped)

Answer 28

- antireceptor antibodies (attachment) - ion cannel blockers, capsid stabilisers, fusion protein inhibitors (uncoating) - inhibitors of polymerases, integrase, transcirptase etc - interferons -> translation, assembly

Answer 29

a form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides some protection for individuals who have not developed immunity theory: chains of infection are likely to be disrupted when large numbers of a population are immune or less susceptible to the disease. The greater the proportion of individuals who are resistant, the smaller the probability that a susceptible individual will come into contact with an infectious individual.

Answer 30

- proteins - nucleic acids - host antibodies

Answer 31

- look for evidence of cytopathic effect (CPE) - primary culture - from sample - continuous culture = from tumour tissue - use immunofluorescence for some

Answer 32

- provides tissues for propogation of herpes, rabies, poxes etc - egg 9-12 days after incubation

Answer 33

1. yolk sac (90 degrees) 2. allantoic sac (45 degrees) 3. chorioallantoic membrane (remove shell) 4. intravenous - in a vein

Answer 34

- visualisation and identification - low sensitivity - useful for unknown virus detection, cheap and quick - using tissue sections that are ultrathin

Answer 35

- Next gen sequencing of nucleic acids - sequences heaps of DNA/RNA at once and generates a ton of info quickly and cheaply - detect unknown viruses -> doesn't rely on having a known target (curve)

Answer 36

- some viruses agglutinate RBCs (cause clumping) - viruses with this property can be tested for 1. equal amounts of antibody to wells 2. prepare serial dilutions of antigen containing smaple 3. add red blood cells after incubated 4. look for haemagglutination (red well)

Answer 37

- serially dilute the virus and place each dilution onto an agar plate - counting the number of plaques

Answer 38

- Enzyme linked immunosorbent assay - detecting antibodies by visualising antibody-antigen complex occurring 1. add antigen to plate in equal amounts 2. add sample (serum/antibody contained) in concentrations 3. bind together (inc period) 4. wash it to get rid of unbound ones 5. add secondary antigen (labelled) which binds to any compounds that remain 6. add substrate which reacts w secondary antigen to produce colour if complex is present -> shows antigen and antibody have bound together

Answer 39

- IgM antibodies first appear in high concentrations (above detection limit) at appx 5 days - short lasting response - IgG antibodies seen at highest conc at appx day 18 (long response) - so taken apart to ID both antibodies and seen different concentrations over

Answer 40

- compliment fixation test -> testing for antibody presence in serum - antigen (serum) and complement added to serum with or without antibody - if antibody present, antigen, antibody and compliment bind together and no haemolysis will occur because complement is stuck in complex - if antibodies not present in serum, complement not attached to them in serum, so binds to second batch of antibodies added and antigen free to lyse cells - add RBCs and antibodies (second batch) - if heamolysis occurs, the compliment is free and has bound to the second antibodies instead.

Answer 41

- Virus neutralisation test - detects the minimum concentration of antibody required to neuralise antigen 1. add equal amount of virus (antigen) 2. add dilutions of antibodies 3. add Red blood cells and allow to grow 4. look for cell death -> the well where cell death doesn't occur first is the concentration at which antibody neutralises all of the virus

Answer 42

- Haemagglutination inhibition assay 1) serially dilute antibody 2) add equal antigen 3) add RBCs - any free viruses will cause haemaglutingation - no haemaglutination = enough antibody added thus the minimum conc to inhibit virus

Answer 43

- Sensitivity = how often a test correctly generates a positive result for people who have the condition that’s being tested for (also known as the “true positive” rate). - Specificity = a test’s ability to correctly generate a negative result for people who don’t have the condition that’s being tested for (also known as the “true negative” rate). - Repeatability = the closeness of agreement between independent test results, obtained with the same method, on the same test material, in the same laboratory, by the same operator, and using the same equipment within short intervals of time.

WEEK 8 Flashcards

(67 cards)