Respiratory Pathogens: Example 1 - influenza A Flashcards
what are 3 features of Influenza A virus itself
- enveloped
- spherical
- 90-100nm diameter
what are the different types of influenza named based on?
named based on their spike proteins
what are the 2 spike proteins found on influenza A
haemagglutinin (HA) + neuraminidase (NA)
what does positive and negative sense mean in genetics
the sense means the direction in which the transcription is read
how many segments exist in the genome on influenza A and how many proteins do these segments enode for?
- genome has 8 segments
- these 8 segments can code for 10-14 proteins
what is the baltimore system
the way to classify viruses
what does monocistronic mean
when genome segments encode for a single protein each and are translated into peptides directly from that genome.
what features make genome sections in influenza A monocistronic?
they are monocistronic because the genome segments:
- are single stranded
- because of their genetic sense
what does PB2, PB1 and PA enzyme proteins allow for influenza A to do?
allows influenza A to transcribe without using the host cell’s machinery
outline the ** lifecycle of influenza A
- influenza A virus present near host cell
- Influenza A adheres to the host cell via spike proteins attachment to alveolar sialic receptors
- This leads to a conformational change and the virus is taken into an endosome via endocytosis
- Influenza A will then uncoat its own envelope and release its genetic information
- the viral RNA released can be copied into a complementary strand using the virus’ own polymerase enzyme, or the viral RNA can go directly to a ribosome and undergo protein synthesis and produce its own proteins
- these proteins will eventually make up a new virion (encapsulated virus particle) through assembly of different parts
- the virion matures and then can go on to infect another host cell, which is called dissemination, or it can infect another individual, which is called transmission.
what is the natural reservoir for Influenza A
birds
what type of virus is influenza A in terms of Spread?
zoonotic virus
how is influenza A transmitted mainly
inhalation
what are the 2 major components to symptoms caused by infection of Influenza A virus
- respiratory tract symptoms
- systemic symptoms
what are 3 examples of respiratory tract symptoms caused by Influenza A infection
- rhinitis (sneezing, itchy nose, runny nose, congestion)
- cough
- shortness of breath
what are 3 examples of systemic symptoms caused by influenza A infection
- fever
- headahcer
- myalgia
what cytokine released by alveolar macrophages causes increased body temperature?
IL-1
what cytokine released by alveolar macrophages cause headaches and general myalgia?
IL-6
what cytokine released by alveolar macrophages causes the liver to release acute phase proteins?
IL-6
what is a pneumotropic virus (influenza A)
a virus that infects cells lining the respiratory tract, down to the alveoli
what is a cytolytic infection (influenza A)
when the infection strips the surface respiratory epithelium
what 2 innate defence mechanisms does influenza A remove by stripping surface respiratory epithelium
- mucous secreting cells
- cilia
what are interferons in defence to?
antiviral defence
what 3 ways are interferons antivirals?
infected cells give off interferons to signal to the neighbouring cells to:
- switch them off and make them dormant and not undergo protein synthesis
- schedule programmed cell death (apoptosis)
- cause neighbouring cells to produce more interleukins
