POM 09 - Influenza Flashcards

1
Q

what are the 4 structural elements of a virus

A

piece of nucleic acid DNA or RNA

protein caspid

envelope - from human cell membranes

viral proteins (haemagglutinin and neuraminidase)

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2
Q

what do viruses need in order to replicate

A

require a host cell for replication

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2
Q

what are the 2 types of influenza A that have adapted to humans

A

H1N1

H3N2

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2
Q

what are cytopathic viruses

A

viruses that damages cell

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3
Q

how many types of influenza B virus are there

A

1

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4
Q

when you experience lethargy and loss of appetite from influenza virus what causes these symptoms

A

mediated by immune system itself - not the virus

caused by cytokine proteins that when they build up in blood stream they react with receptors in the brain and cause illness

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5
Q

what are viral proteins in terms of where they are located and what they do

A

protein on surface of virus that allows it to bind to its target cell (for influenza its the epithelial cells of the upper airways)

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6
Q

what does haemagglutinin do and how can it be used to prevent influenza dieases

A

attach to residues called sialic acids

if immune system antibodies bind to haemagglutinin then it cant bind to sialic acid in the nose, as such these neutralising antibodies prevents the infection from taking place

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7
Q

what is antigenic drift in terms of the influenza virus

A

influenza viruses frequently mutate and their surface proteins/antigens change

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8
Q

what is antigenic shift in terms of the influenza virus

A

a new type of influenza A virus arises

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9
Q

what is the difference between antigenic shift and antigenic drift

A

antigenic drift is a mutation in virus that is continuous and under selection pressure of human immune system - it is a slow process due to mutations and only occurs in influenza B

antigenic shift is an abrupt change in genes that make up the influenza A virus

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10
Q

what is an example of how influenza B has undergone antigenic drift regarding HA and antibodies

in terms of what normally happens and what happens after drift occurs

A

normally the immune system reacts to the virus and forms antibodies to it which can bind to the haemagglutinin molecule and prevent it from binding to the sialic acid in our nose

however the drift can cause the virus to mutate such that the haemagglutinin changes shape/protein structure so that overtime it changes so much that infection cannot be prevented by the antibodies and person is no longer immune

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11
Q

what does neurominidase do

A

snips the reaction between sialic acid and haemagglutinin to allow viral particle to leave the cell

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12
Q

how do neuraminidase inhibitors treat influenza

A

if neuraminidase is inhibited then the virus particle cant be released from sialic acid to infect other neighboring cells

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13
Q

when is seltamivir and zanamivir effective in treating influenza

why is this

A

at the beginning of the infection before lots of cells are already infected - if infection is already in the cells of nose and throat then drugs dont do anything as there are no more cells to prevent virus spreading to

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14
Q

what are 2 types of neuraminidase inhibitors

A

seltamivir and zanamivir

15
Q

the influenza vaccination is trivalent - what is meant by this

A

it contains proteins of H1N1, H3N2 and B

16
Q

why is a new vaccine required most years

A

due to antigenic drift