Influenza lecture

Question 1

viruses are made up of

Answer 1

nucleic acid, protein coat, lipid envelope and vila proteins

Question 2

virus basics

Answer 2

only replicate once host cell is infected

Question 3

nucleic acid

Answer 3

either RNA or DNA

Question 4

shape of virus

Answer 4

helical or isosahedral

Question 5

lipid envelope

Answer 5

originates from host cells

Question 6

stages of viral replication

Answer 6

1) virus enter cell by pinocytosis
2) virus sheds coat
3) replication of viral nucleic acid
4) synthesis of viral protein of capsid
5) assembly of new virion
6) release of new virion

Question 7

what part of the virus facilities entry of the virus into the host cell

Answer 7

hem agglutinin- binding to sialic acid

Question 8

what facilitates the release of the virus from infected host cell

Answer 8

Neuraminidase

Question 9

viruses are classified based on

Answer 9

size, shape, type of nucleic acid in genome

and who they produce mRNA

Question 10

how host cell synthesise protein

Answer 10

DNA is converted to complementary strand RNA in nucleus
mRNA moves out into cytoplasm where it attaches to a ribosome
mRNA acts as a template- amino acid binds to

Question 11

non-sense RNA virus

Answer 11

1) replicating virus- nonsense RNA (viral RNA polymerase. RNA to RNA)
2) RNA
3) Ribosome produces caps protein from ribosome

Question 12

sense RNA virus

Answer 12

1) Replicating virus- sense RNA
2) viral RNS polymerase (RNA to RNA)
3) RNA
4) RNA polymerase (RNA to RNA)
5) Ribosome produces caps protein from ribosome

Question 13

sense RNA virus

Answer 13

cant act as RNA template

Question 14

sense RNA virus cant act as RNA template

Answer 14

1) replicating virus. Sense RN that can not act as an RNA template
2) viral reverse transcriptase (RNA to DNA)
3) DNA
4) host RNA polymerase (DNA to RNA)
5) RNA - ribosome - capsid protein

Question 15

Baltimore classification

Answer 15

virus classification system that groups viruses into families, depending on their type of genome (DNA, RNA, single-stranded (ss), double-stranded (ds), etc..) and their method of replication.

Question 16

how many groups in baltimore system

Answer 16

7

Question 17

viral enzyme shave

Answer 17

low proof reading ability

Question 18

mutations least likely in

Answer 18

Group 1- DNA -due to the host having proof reading machinery already

Question 19

why are mutations more likely in other groups

Answer 19

more steps- mutations more liekly

Question 20

types of genomic shift

Answer 20

drive and shift

Question 21

drift

Answer 21

point mutations, make small changes

Question 22

shift

Answer 22

Antigenic shift is the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains.

happened when a genome is segmented. when pandemic occur- completely changes antigens
- unrecognisable

Question 23

example of a virus that has undergone genetic shift

Answer 23

H3H2 influenza virus

- mixture of H3 avian virus and H2N3 human virus

Question 24

how virus which aren’t dangerous to humans becomes dangerous

Answer 24

• Type of influenza which infects a birds cannot infect a human, however the type of influenza virus that effects birds or humans, can both infect pigs. Therefor if we have a pig infected with both avian and human influenza, a type of new influenza (genomic shift), which can infect humans can be produced

Question 25

ham agglutinin is an antigen that is variable between subtypes ?

Answer 25

true

Question 26

genomic drift implies new vaccine is required

Answer 26

false-antigens will still be similar so same vaccine may work

Question 27

if virus are very small and cannot be visualised under a microscope what could be used for them to be detected

Answer 27

- ELISA - PCR looking for viral DNA - RT-PCR looking for RNA virus

Question 28

can only use ELISA

Answer 28

when the body has started producing antibodies at day 5

Question 29

when the patient has just started reporting symptoms look at

Answer 29

site of infection e.g. nose or pharynx

Question 30

look for antibodies in

Answer 30

the blood

Question 31

throat swabs form patients convalescing 9recovering) from an infection are the most useful sample for oral testing?

Answer 31

false - better off looking for antibodies

Question 32

the plaque assay

Answer 32

used to measure virus time

Question 33

to performa a plaque assa

Answer 33

o 10-fold dilutions of a virus stock are prepared, and 0.1 ml aliquots are inoculated onto susceptible cell monolayers. o After an incubation period, to allow virus to attach to cells, the monolayers are covered with a nutrient medium containing a substance, usually agar, that causes the formation of a gel. o When the plates are incubated, the original infected cells release viral progeny. The spread of the new viruses is restricted to neighbouring cells by the gel. o Consequently, each infectious particle produces a circular zone of infected cells called a plaque. o Consequently, each infectious particle produces a circular zone of infected cells called a plaque. o Eventually the plaque becomes large enough to be visible to the naked eye. Dyes that stain living cells are often used to enhance the contrast between the living cells and the plaques.

Question 34

why may plaque assay not be best

Answer 34

takes a bout a fortnight to get results back-not best if an outbreak

Question 35

what is a positive result with qualitative RT-PCR

Answer 35

an increase in fluorescence

Question 36

qPCR

Answer 36

- Quantitative reverse transcription polymerase chain reaction, is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR, i.e. in real-time, and not at its end, as in conventional PCR.

Question 37

hameagglutination assay

Answer 37

quick way of measuring the amount of virus in a sample | - only works with viruses which bid to RBC

Question 38

assays rely on the fact

Answer 38

we can see what happens with RBC with the naked eye

Question 39

in a tube of blood..

Answer 39

abc will sink to the bottom of the tube due to gravity

Question 40

if we mix the right quantity of virus with the right quantity of rbc

Answer 40

then shield at the bottom of the tube will form

Question 41

why will a shield at the bottom of the of the tube form

Answer 41

due to the virus binding to sialic acid, causing cross linking between abc, forming a lattice and spreading to fit the bottom of the tube

Question 42

qRT-PCR can be used to distinguish diff influenza subtypes?

Answer 42

True- use PCR to look for virus, can tailor it so we have primers which pick out speicifc subtypes e.g. H1, H2 or H3

Question 43

when thinking if PCR can determine if specific dna is there

Answer 43

think specific primers

Question 44

Anti-N ELISA tests for exposure to a virus or vaccine

Answer 44

Yes- my body has seen this virus or through a vaccination and has produced anti bodies against it

Question 45

if virus is present

Answer 45

shield will be formed instead of button

Question 46

the hameaglgutination INHIBITION test produces a (antibody present)

Answer 46

a button since the reaction steps the virus from binding so abc fall as a button- no lattice formed

Question 47

viral detection in clinical samples

Answer 47

- Genomic techniques - Antibodies against them - Cell culture - Hameagglutination - Plaque assays - ELISA

Question 48

sample for hamealgutination assays must be taken

Answer 48

at acute stage- symptoms | -second serum taken during convalescent stage- when antibodies ar eliekly to be present

Question 49

why in hameglutination inhibition assay is a button a positive result

Answer 49

since antibody has captured the virus so abc has fallen to the bottom as a button

Question 50

example of how haemagglutiantion assays can be used

Answer 50

- When john was acutely ill there were not many antibodies against H1 or H3 - However when he was recovering he had many positive button results for wells with antibodies against H1, but few positive results for H3 antigens - Therefor he is likely to have suffered an infection from an H1 virus