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is a group of RNA virus which causes respiratory disease of the family Orthomyxoviridae, genus "Influenza virus A","Influenza virus B","Influenza virus C" and respective species A, B, and C

it is likely that all the epidemics of influenza derived from humans living in close proximity to poultry or pigs, and poultry is a natural reservoir for the disease.

Of the 3 main subtypes (A,B,C) A is responsible for the major pandemics of human flu infections including Spanish flu of 1918 and Swine Flu of 2009.

The disease is transmitted by airborne particles and infects the epithelial cells of the upper respiratory tract.

@todo some images of infection and cells http://www.technion.ac.il/~mdcourse/274203/lect13.html http://www.comprehensivephysiology.com/WileyCDA/CompPhysArticle/refId-cp030211.html


Structure Edit

the capsid contains a single strand (-ssRNA) of RNA and the viral enzyme RNA polymerase

around the capsid there is a membranous envelope which contains neuraminidase (NA) and haemagglutinin (HA) [1]

haemagglutinin is named because it can bind to red blood cells and causes haemagglutinination

The glycoproteins HA and NA are spike like, protruding 10nm from the surface of the virion

Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending extracellularly, the extracellular segments are often glycosylated. Glycoproteins are often important integral membrane proteins, where they play a role in cell–cell interactions.

Subtypes Edit

IN virus classification, the family Orthomyxoviridae contain a number of genera, including a genus for each influenza A, B and C, however each genus contains only a single species, that corresponding to the genus name.

INfluenza typa C undergoes little antigenic variation, and B only drifting at a slow pace.

However subtype A mutates yearly and is the major source of health problems.

The N and the H in N1H1 refer to the antigens of N of NA and the H of HA respectively

in the near shift occurs, the emergence because of Asian flu (H2N2) lack immunity to H2N2

will effect younger people, because they have no immunity to H2N2 for 40 years

type C can be divided into serotypes based on the antibody reponses to the antigen changes to the N and H proteins.

Antigen Type
H1N1
H2N2 1957
H3N2 Hong Kong 1977
H1N1 Russian
H2N2
H5N1 Hong Kong 1997 isolated also in chickens and other birds in Hong Kong
H10N7 US
H7N3 US
H7N2 US


Viral Proteins Edit

3 transmembrane proteins

NA
HA

Lifecycle Edit

Drugs Edit

Amantadine Edit

the first antiviral approved for Influenza was Amantadine hydrochloride

Amantadine is not effective against influenza B or C

Is administired orally, but is associated with neurological disorders in a subset of patients


Rimatadine Edit

derivative of Amantadine, deliverd orally


Ribavirin Edit

1972


GG167 Edit

poor absorption via GI

congener of neuraminic acid





PM-523 Edit

inhibits fusion of virus for influenza A


phagosome Edit

A phagosome is a vesicle formed around a particle absorbed by phagocytosis. The vacuole is formed by the fusion of the cell membrane around the particle. A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested. Phagosomes fuse with lysosomes in their maturation process, forming phagolysosomes.

Some bacterial pathogens that enter cells inside phagosomes either reproduce inside of the formed phagolysosome or escape into the cytoplasm before the phagosome fuses with the lysosome. Many mycobacteria, including Mycobacterium tuberculosis [3] [4] and Mycobacteria avium paratuberculosis, manipulate the host macrophage to prevent nitrous acid-containing lysosomes from fusing with phagosomes and creating mature phagolysosomes. Such incomplete maturation of the phagosome maintains an environment favorable to the pathogens inside it.

[2]

During the adsorption phase of the viral lifecycle, the low pH of the endosome causes a conformal change in the HA2 protein which opens up ...

This process of penetrating target cells is unique to influenza viruses


BMY-27709 Edit

  1. patrick 2009
  2. http://en.wikipedia.org/wiki/Phagosome
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