Viral Disease Slackers Facts by Mike Ori
Disclaimer The information represents my understanding only so errors and omissions are probably rampant. It has not been vetted or reviewed by faculty. The source is our class notes. The document can mostly be used forward and backward. I tried to mark questionable stuff with (?). If you want it to look pretty, steal some crayons and go to town. Finally… If you’re a gunner, buck up and do your own work.
A new vaccine is required each year because of antigenic drift due to polymerase errors
The virus causes destruction of ciliated respiratory epithelium in the upper respiratory tract. This degrades the mucociliary elevator and prevents efficient clearance of bacteria. General immune system down regulation occurs as the influenza infection is controlled.
What is the basis for the increased virulence seen in H1N1 of swine origin
Antigenic shift has substantially altered the virus to reduce its antigenic similarity to previous strains and to allow it to replicate in both the upper and lower respiratory tract.
Why are people over 50 less likely to get sick from H1N1 swine origin.
An similar pandemic occurred within their lifetime. They do not have as robust an immune system and cannot generate as much of a cytokine storm
Currently the strain’s H antigen interact with sialic acid alpha 2,3 gal receptors which are situated in the lower respiratory tract. Thus it take larger exposures to transmit the disease.
Why are swine important intermediates in the assortment of avian and human influenza?
Swine upper respiratory epithelium contains sialic a2,3 gal and sialic a2,6 gal receptors thus they can be easily coninfected with both human and avian virus. This allows nature to tinker. Idle goddesses are the devils workshop.
What will happen if H5N1 reassorts or mutates to efficiently infect both upper and lower respiratory epithelium.
New human type A strain Causing serious illness Easily spreads person to person
Mumps Parainfluenza and croup Rubeola (5 day measles) Respiratory syncitial virus
Combined H and N on single spike (para=next to hence H is para to N) Fusion (F) protein on second spike
A syncitia is a giant cell that forms by fusion of multiple cells. Paramyxovirus tends to form syncitia through the action of F protein deposited on cell surfaces.
Parainfluenza = bronchitis RSV = bronchiolitis
Occurs from the late fall to the spring. Predominantly affects small children < 1 yo.
Immunity is incomplete. Repeated infections occur with lessened severity but its unclear if there is an immune basis.
Injection of monoclonal antibody against factor F is indicated in high risk children
It looks like a cold but also has Myalgia/arthralgia Fever