{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

27 - Respiratory viruses 1 Categories of Respiratory...

Info iconThis preview shows pages 1–16. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Respiratory viruses
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 Categories of Respiratory Viruses Orthomyxoviridae: Influenza virus Paramyxoviridae : Parainfluenza virus; Mumps virus; Measles; Respiratory syneytical virus Togaviridae: Rubella Virus Coronaviridae: Corona Virus; SARS virus Adenoviridae : human Adenovirus picornaviridae: Rhino Virus; Reoviridae:
Background image of page 2
3 Influenza virus Orthomyxoviridae: Influenza virus Influenza is a disease caused by Influenza virus ,a member of the Orthomyxoviridae.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
4 Genome of Influenza virus 8 negative sense RNA nucleocapsid segments The 'RNP' (RNA + nucleoprotein) is in a helical form with the 3 polymerase polypeptides associated with each segment. The segmented genome promotes genetic diversity caused by mutation and reassortment of segments on infection with two different strains
Background image of page 4
5 Virion spherical/ovoid, 80- 120nm diameter, The inner side of the envelope is lined by the matrix protein, stable type- specific.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
6 Virion The outer surface of the particle consists of a lipid envelope from which project prominent glycoprotein spikes of two types, the haemagglutinin, ~135Å trimer (HA), and neuraminidase, ~60Å tetramer (NA).
Background image of page 6
7 Haemagglutinin (HA) Encoded by  RNA  segment #4  Can agglutinate red blood cells - hence the nomenclature  Cleavage by host-cell protease is required (resulting in  HA1   and  HA2 ) for infection to occur  Hemagglutinin glycoprotein is the viral attachment protein and fusion protein , and it elicits neutralizing , protective antibody responses
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
8 Neuraminadase (NA)   Encoded by  RNA  segment #6  Enzyme that uses neuraminic (sialic) acid as a  substrate  Important in releasing mature virus from cells
Background image of page 8
9 ORTHOMYXOVIRUSES M1 protein helical nucleocapsid (RNA plus NP protein) HA - hemagglutinin polymerase complex lipid bilayer membrane NA - neuraminidase type A, B, C : NP , M1 protein sub-types: HA or NA protein
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
10 Influenza virus A
Background image of page 10
11 Replication Influenza transcribe and replicates its genome in the target cell nucleus assemble and buds from the plasma membrane
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
12 Influenza virus
Background image of page 12
13 Antigen Soluble antigens: include ribonucleoprotein and M protein which are much stable in antigenicity. Surface antigens: include HA and NA which are much variable in antigenicity.
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
14 Types Influenza viruses are divided into  3  groups  determined by the ribonucleoprotein (RNP) antigen  and M antigen:  Group A  - This group is the cause of epidemics and  pandemics and has an avian intermediate host (IH) Group B  - This group causes epidemics and has no  IH Group C  - This group does not cause epidemics  and causes mild disease
Background image of page 14
15 TYPE A ++++ yes yes yes shift, drift yes sensitive sensitive 2 severity of illness animal reservoir human pandemics human epidemics antigenic changes segmented genome amantadine, rimantidine zanamivir surface glycoproteins TYPE B ++ no no yes drift yes no effect sensitive 2 TYPE C + no no no (sporadic) drift yes no effect (1)
Background image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 16
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}