MICR 121 Lecture Notes - Lecture 11: Emerging Infectious Diseases, Pokey, Hemagglutinin
9 Nov 2016
School
Department
Course
Professor
Week 11: Session 2
Emerging Infectious Diseases
MICR121
March 24, 2014
Influenza
• Influenza (U.S.) causes over 100,000 hospitalizations per year
• Influenza (U.S.) causes over 35,000 deaths annually
• Influenza is preventable by a vaccine
• Neonates who get influenza have a high mortality
• Think of it as a disease across the spectrum of life
o Affects the very young and the very old severely
What does influenza do?
• Destroys ciliated epithelial cells of respiratory tract
• Infected the ciliated epithelial cells of the respiratory tract – kills those
cells
• People who die from it most often die from a super-infection from
something else because the patient is losing the mucociliary elevator –
lost the most important non-specific defense actor there is
Influenza Infecting the Host Cell
• To infect a cell, the virus must first find the right cell
• The cell must have receptors
• The virus must attach to the receptors
Influenza Virus Structure
• Hemagglutinin (HA) → red pokey things in picture
• Neuraminidase (NA) → green pokey things in picture
o These are the two antigens of the virus
HA and NA
• Hemagglutinin (HA)
o Binds the virus to the host cell receptors
o Helps get the virus into the cell
• Neuraminidase (NA)
o Helps the virus escape from the host cell so it can infect another
cell
Influenza viruses
• Three types: A, B, C
o A infects both humans and animals (pigs, birds, horses)
o B humans only
o C mild disease
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Influenza (u. s. ) causes over 100,000 hospitalizations per year. Ha and na: hemagglutinin (ha, binds the virus to the host cell receptors, helps get the virus into the cell, neuraminidase (na, helps the virus escape from the host cell so it can infect another cell. Influenza viruses: three types: a, b, c (cid:1684)a(cid:1685) infects both humans and animals (pigs, birds, horses) (cid:1684)b(cid:1685) humans only (cid:1684)c(cid:1685) mild disease. Influenza is difficult to prevent and control because the virus is able to disguise itself and fool the body(cid:1685)s immune system into thinking it has never encountered the virus before. Antigenic shift: only influenza a is capable of what is know as sudden major antigenic changes, change of host, thought to be a result of avian strains that can change and now infect humans, blame the pig! Cycling: virus hides until population susceptible again, ex. Vaccine efficacy: pigs are closely associated with other farm animals, we domesticate pigs associated with humans.
