Measles is one of the most contagious diseasesknown to man.
In fact, if someone with measles coughs in an elevator,
90 % of the people who use that
elevator after will catch the disease.
Unless of course you’ve been vaccinated.
Then you’ll be completely fine.
This is the measles virus,
it’s been around for thousands of years
and has been responsible for
the deaths of millions of people.
Now, on the surface,
measles symptoms seemfairly innocuous.
But the real damage,
the damage that can lead to death, happens on a cellular level.
大家好 我是Roberto Cattaneo
Hi I’m Roberto Cattaneo.
I’m a Doctor of Philosophy and Professor of Molecular Biology at the Mayo Clinic.
I’m studying the measles virus since about 35 years.
Measles uses the tracheaas a trampoline.
It is in the ideal position
in the body to get expelled and aerosolized dispersing
in the air in small particles very efficiently.
When someone with measles coughs or sneezes,
these droplets contain the measles virus,
and because measles is a respiratory disease,
all someone needs to do is breathe in that
infected air in order to contract measles.
Unless, of course, they’ve been vaccinated.
When the measles virus reaches the lungs,
it is met by a type of white blood cell called a macrophage.
Usually,macrophages seek out and destroydangerous pathogens like viruses.
But the measles virus tricks the macrophage into not
seeing it as a danger
and instead, safely transports the virus into the body’s lymph nodes.
It’s here that the virus begins to replicate
and spread the entire lymphatic system.
Yea, I mean the macrophages thinks to have a system
in which they basically get rid of the virus.
And measles can stay there.
So not only it is invisible
but it begins to make damage to these cells.
The task of these cells is
also to go out and fight infection,
but instead of fighting infection,
they go out with the virus
and distribute it to the body.
Now, as the virus starts to spread,
it enters immune cells that express a protein named SLAM
These cells are “ memory ” immune cells,
meaning that they remember other pathogens
that previously infected the host.
Measles attacks and kills these SLAM-expressing memory cells
and once those memories of past infections are erased, the body will be
in a much weaker position to fight off future infections
This is why measles is so deadly.
But even though the virus has tricked your immune system to helping it,
that doesn’t mean your immune system has given up.
Well, at some point the immune system will notice
and will secrete cytokines and attract other immune cells.
so at some point the enemy will be identified
and taken care of.
But for the viruses in fact it is only necessary to get out of the host
and find a new host.
So it’s in fact better not to kill the host.
It’s in the best interest of the virus not to kill you,
that’s some other diseases job.
The job of the measles virus is to find a new host,
which brings us to another protein the virus receptor: nectin4.
我们发现nectin 4 蛋白是一种上皮受体
And we discovered nectin 4 as the epithelial receptor
or host exit receptor for measles virus.
As measles spreads throughout the body,
it also enters cells that express the protein nectin4.
This protein is expressed very preferentiallyin the trachea.
And the more the virusit replicates in the trachea,
the more cells it kills there.
This dead cell build up actually
causes the human host to cough or sneeze,
helping spread it into a new human host,
bringing us right back to where we started.
Now, the good news is that
once you get the measles,
your body learns how to defeat it
and you probably won’t get it again.
This is similar to how the vaccine works,
but the difference is you’re given a weaker dose,
so you can become immune without getting sick
or damaging your immune cells.
So the vaccine causes the host to remain immune to measles
we think for life long or almost life long time.
And without measles, other diseases,
the ones that actually do the killing, have gone down.
Basically the number of hospitalization
has been reduced considerably sometimes to
about the half for several different infectious diseases.
if you haven’t been vaccinated…
Yea,the vaccine works beautifully.
Maybe think about it?
Measles may be the enemy of the immune system,
but researchers, including Dr Cattaneo,
are working on ways to alter the measles virus，
so it kills cancer cells.
a reason to continue study measles is to make it into a friend,
making an old enemy into a new friend by modifying it genetically.