“Viruses are just like us, they are part of nature. In so many years of co-existence, they have shaped our immune system and even become some of our An indispensable part of important physiological functions.” This article is from the official account:Gezhi Lundao Forum (ID: SELFtalks) author: Zhu Huachen (Shantou University, University of Hong Kong, deputy director of the joint Institute of virology), from the title figure: the movie “new mummy”
When it comes to viruses, it must be the new crown that cannot be avoided.
As you can see, this epidemic in 2020 has changed the lives of every one of us.
As of August 23, all
Characteristics of emerging infectious diseases
When we look back over the past 30 years, in fact, we have experienced many and various new infectious diseases, such as avian flu, swine flu, SARS, MERS, new coronavirus, and Nipah, Hendra, Ebola, Zika, Mad Cow Disease, etc.
Compared with these emerging infectious diseases, they have some common characteristics.
First of all, it is new. Because it is new, most of us don’t have antibodies. In addition, we do not have a vaccine, and it is difficult to predict what the next new infectious disease will be.
The second feature is that These new infectious diseases all come from animals.
In addition, we noticed that except for the prions that cause mad cow disease, all others are RNA viruses.
In the ecosystem where we live, we have to come into contact with many animals every day, or live with them in the same environment.
There are all kinds of domestic animals, pets, wild animals, and sometimes mosquitoes cross different animal species, bringing pathogens to us across borders.
In the past thousandIn millions of years of co-evolution, viruses have actually reached a good balance with their own hosts. In most cases, they have nothing to do with their natural hosts.
However, as a new host, we humans, if we accidentally or accidentally expose ourselves to pathogenic environments, or come into contact with these virus-carrying animals, we may be infected.
Because we don’t have a pre-existing immune system, or antibodies.
On the other hand, if pathogens happen to have the ability to spread across species, they may infect humans and cause serious public health incidents.
As mentioned above, most of the pathogens of these new infectious diseases are RNA viruses. What are the special features of RNA viruses?
RNA viruses are so easy to cause new infectious diseases. One of the reasons is that the RNA virus genome is very small, replicates quickly, and has a very high mutation efficiency.
For RNA viruses, its RNA polymerase has no correction function and fidelity function, so many mutant offspring will be produced every time during the replication process.
The offspring of these mutations can easily find an adaptive environment in different environments and different hosts, and the characteristics of this adaptation can be passed down continuously.
On the other hand, because the mutation rate of RNA viruses is very fast, this leads to a bad result. When we finally find a medicine, a vaccine or an antibody, RNA viruses are very It is easy to get resistance through mutations, or escape through immunity.
Our human genome has 3 billion base pairs. For RNA viruses, the largest is the coronavirus. Its genome is only 30,000 bases. Compared with humans, 30,000 bases is one hundred thousand points. one.
In addition, the smallest RNA virus in the world we know so far is hepatitis D virus.
Hepatitis D virus has a total of more than 1,600, nearly 1,700 bases. These 1700 bases encode only one protein, which can continue to pack itself into two isomers, one large and one small.
In the middle part, the blue circle is the large protein and the small protein, which combine to wrap the middle group of nucleic acids.
The outer circle is the cell surface membrane that the virus gets from the cell, andSome proteins of other viruses.
So the virus is a very streamlined and very economical life form. It can make best use of the resources it can get in the cell.
A virus that is also an enemy and a friend
Every time we mention “virus”, what we can think of is always “ill” and “poisonous”, which seems particularly terrible.
You definitely want to get rid of the virus quickly, right?
Actually, in the process of evolution, the really smart virus is definitely not the kind of virus that makes the host seriously sick or even dead.
For a living body, the biggest and essential task is to copy and preserve itself, and to extend its genome to the greatest extent possible.
So, from the point of view of the virus, killing, maiming, or making the host sick is not in its basic interests. The really smart virus must be the kind that silently lurks in the body. Some viruses that use the host silently and benefit from it silently.
Each of us can carry as many as 100 trillion microorganisms. If a person weighs 100 kilograms, we have at least one to three kilograms of bacteria.
As you can imagine, we humans or other animals are like a walking microbial library, we carry a lot of pathogens and live here every day.
Just like in our respiratory tract, there are about a hundred kinds of viruses living in them all year round. So many viruses live here, what are their effects on our bodies, and what are they doing there?
In most cases, if our immune system is normal, we are in peace with the virus.
On the other hand, the existence of a virus may also have certain benefits for our body.
For example, we know that there are many probiotics in bacteria, which are good for the body.
I also do not rule out the possibility of viruses. When these relatively mild viruses occupy your body, they actually have a repelling effect on some powerful pathogens.
These very mild and very mild viruses exist in the body and can stimulate the body to produce a certain immune response from time to time. These immune responses can help you remove diseased cells in the system, even tumor cells.
So it should be said that the virus has reached a balance with us, which may be good for our body.
In terms of evolutionary history, the most successful virus may be a retrovirus.
As mentioned above, the human genome has 3 billion base pairs, 8% of which are from viruses, especially retroviruses.
So it can be said that these viruses have become a part of our bodies in hundreds of millions of years of evolution.
For example, our immune system, reproductive system, neuromodulation, and some cognitive functions, even memoryThe function of memory is more or less related to the regulation of retroviruses and the genes they inherited to us.
The most famous example is the syncytin protein encoded by retrovirus.
The syncytin protein exists in the head of the sperm. When the sperm is looking for the egg, the syncytin protein can help the sperm find the egg and hook it with the protein on the egg to help the sperm and egg occur. Cell fusion.
Why is it called syncytin? Because it can promote the fusion between two cells.
In addition to the combination of sperm and egg, for mammals, when the fetus is in the mother’s stomach, it must obtain the nutrition and oxygen supplied by the mother through the placenta.
However, as a foreign body, the fetus is not actually attacked by the mother’s immunity. Why?
Actually, there are many genes left by retroviruses in the placenta. Some of these genes can help us regulate and prevent the mother’s immune system from recognizing and attacking the fetus.
There are also some genes, like the syncytin gene just mentioned, which can promote the fusion between cells, connect with the placenta through the umbilical cord, and further connect with the mother’s body.
So, in this case, retrovirus shaped mammals and helped our evolution.
Next, take a look at another small virus with a halo, its name is adenovirus.
On its cell surface, the small protrusions we see are some small proteins and small tools that it recognizes cell receptors.
Adenovirus is a very common virus in animal groups, and it is relatively mild. Like us humans, we are infected with adenovirus many times in our lifetime.
Places where adenovirus usually infectsOr to deal with some products of diseased genes, through viral infection, some useful drugs can be released instantaneously. These drugs can help us accurately realize the function of treating and correcting misexpressed genes.
Like the adenovirus just mentioned, it also shines in the application of oncolytic viruses.
For example, when we load a virus with a tumor-targeting gene, or a gene that specifically kills tumors, adenovirus and other viruses can be used by us and become a “nuclear missile that targets tumors.” “.
In the past 100 years, because Fleming discovered antibiotics, bacteria are no longer a big problem for us.
In recent years, due to the abuse of antibiotics and the evolution of bacteria, there are now more and more resistant bacteria, and there are even various super bacteria that have no inhibitory effect on antibiotics.
We say, The enemy of the enemy is our friend.
As mentioned above, bacteria also have their own unique viruses, viruses that specifically infect bacteria without infecting other animal and plant cells. We usually call it bacteriophages.
Bacteriophages can actually help us to become a big killer specifically to deal with super bacteria or other harmful bacteria.
Speaking of this, do you think that viruses don’t seem so annoying, but terrible?
Always be prepared for the virus
However, the so-called non-self race must have different hearts.
As a virus, it continues to evolve. If we don’t understand it well and study it, they may come back one day in the future, causing more serious harm to us.
So we must always be prepared, thoroughly research, and figure out the other side’s pathogens that look like enemies but not enemies, like friends but not friends.
The picture below is the interior view of the State Key Laboratory of Emerging Infectious Diseases at the University of Hong Kong. On the far right is the door to the Level 3 Biosafety Laboratory. This door is a completely airtight door.
When the inflator is closed, even if you flood it with water, the water cannot penetrate the door, so it is very airtight and very safe.
The basic design concept of the biosafety laboratory is a large box made of all stainless steel, with small boxes inside the box. When you walk inside, the air is pumped into negative pressure, so the air can only be from the outside Flow inside, and not flow backwards from inside to outside.
All incoming air must be filtered and disinfected layer by layer, the released air must also be disinfected and filtered, and other things must pass through high temperature and high temperature.Only by pressing, chemical disinfection and fumigation can it be brought outside.
In our daily work, we first search for viruses in various places where viruses may exist, monitor the viruses, and see if there are any abnormal changes in the virus recently.
If we find some suspicious viruses or viruses that are at risk, we will bring them back to the laboratory and put them in different animal models to see what their pathogenic mechanism looks like and why It will have better transmission or pathogenicity.
In addition, we will also develop vaccines, drugs, and monoclonal antibodies through various modern biological technologies, all of which are to enable us to coexist and cope with the virus better.
After telling the story of the virus, I should say that viruses are just like us, they are part of nature.
Moreover, in so many years of living together, it has shaped our immune system, and has even become an indispensable part of our important physiological functions.
Don’t look at it as simple. In fact, it is not inferior to us. Everyone can evolve together to this day, that is, everyone has adapted to our own environment and everyone is a successful survivor in the evolutionary process.
We said that there are no permanent enemies and no permanent friends. The key is how we should understand each other, use each other, transform each other, and use each other well.
Finally, what I want to say is that virology is actually a very interesting research field. In addition to our biological, medical, and chemical industries, this industry also requires a lot of physics, engineering, and chemistry. Mathematics and computers.
So I very much hope that more people from the younger generation can join us. Everyone cooperates, communicates, and coordinates with each other. Only in this way can we understand our opponents more clearly, transform them, make good use of them, and achieve The ultimate goal of mutual balance and common development.
This article is from the official account:Gezhilun Dao Forum (ID: SELFtalks), author: Zhu Huachen (Shantou University, deputy director of the joint Institute of virology, University of Hong Kong)