Freshers Flu Flashcards
Differences between cold and flu symptoms
Flu has a more rapid onset whereas cold has a gradual onset
Sneezing is more common in cold
Headaches are common in flu
How are strains identified
By their subtype, geographical origin,year of isolation and species of origin
Causative agents of common cold
Rhinovirus
Coronavirus
Influenza virus
Adenovirus
Causative agent of flu
Influenza virus
Renin angiotensin pathway
Local infection leads to production of angiotensin I which is converted to angiotensin II by ACE
Angiotensin II binds to angiotensin II type 1 receptor. Thus causes vasoconstriction vascularpermeability acute lung injury and myocardial remodeling.
ACE2 catalyses conversion of angiotensin I into angiotensin (1-9)
Angiotensin IIinto angiotensin (1-7)
These both are vasodilators and lower angiotensin II levels
Effect of sars-cov-2 on the renin angiotensin pathways
Spike protein on sars cov 2 binds to ACE2 allowing virus to enter cell
ACE2 is downregulated
So less angiotensin (1-9) and (1-7) are made
Due to virus more angiotensin II is produced
Less angiotensin (1-9) and (1-7) means that effects of angiotensin can’t be opposed
Influenza virus mechanism
Sialic acid are found in glycoproteins on the cell surface membrane of endothelial cells and erythrocyte
Virus contains haemagglutinin(HA) which binds to sialic acid allowing virus to enter.
Virus also contains neuraminindase(NA) which is a glucoside hydrolase enzyme that cleves sialic acid
HA binds to sialic acid when virus leaves the cell so cleavage important to allow for exit
Lots of sialic acid present in lower respiratory tract
Rhinovirus mechanism
Binds to ICAM1 protein
Effect of exercise
Increasing exercise increases cortisol levels which leads to immunosuppresion thus increasing risk of infection
Stress
Increasing stress increases cortisol levels thus increases immunosuppresion
Sleep
During sleep WBC move into lymphoid tissues where they encounter the virus
Less sleep means less wbcs exposed to virus so weaker immune response
Influenza A vs influenza B vs c
Influenza A has three membrane glycoproteins HA NA and matrix 2
Influenza B also has HA and NA and two other proteins
Influenza C is structurally different
Antigenic drift
Natural mutation that occurs over time resulting in small genetic change
Immune system should still recognize it overtime however viruses may have different antigenic material
Antigenic shift
Abrupt major change
Requires an entirely new genetic response so population have little or no protection
Only occurs in influenza A
Occurs when two or more different strains if a virus infect the same cell their material combines to produce progeny with new HA/NA combinations
Heamgluttinin and neuraminidase
There are 18 types of HA and 9 types of NA
