Through the last course, we learned that the three main culprits that make us sick are bacteria, viruses, and DNA mutations.
These pathogens are extremely small, extremely numerous, and extremely fast. Although our immune system is fighting with them all the time, every time our immune system is too late to react or eliminate, our body will appear big. Diseases large and small.
In our daily lives, the common cold is such a frequently occurring disease, and it is closely related to our immunity.
Nasal congestion, runny nose, sneezing, sore throat, cough, fever, etc. that usually occur are common symptoms of the common cold. The common cold, also known as upper respiratory tract infection, is a common respiratory disease caused by a variety of viruses, 30%-50% of which are caused by serotype rhinovirus, including adenovirus, Coxsackie virus, and respiratory tract Syncytial virus.
According to the survey, adults have an average of 2-6 colds per year, and children have more colds. Under normal circumstances, most people can slowly recover by their own resistance, but for people with impaired immune and respiratory systems, a cold may develop into a more serious disease.
Perhaps the common cold is not enough to attract our attention, but the flu, that is, influenza, has to be paid attention to. Its pathogen is the influenza virus among the viruses, which are mainly divided into types A, B, and C. Among them, influenza A viruses often mutate and produce multiple subtypes, which can easily lead to influenza outbreaks.
From the ancient Greek period to the present, there have been more than a dozen influenza pandemics recorded in human history. In the past hundred years, influenza has spread rapidly around the world, centered on Europe, and then repeatedly appeared in human society, causing hundreds of millions of infections and tens of millions of deaths. To this day, Europeans and Americans still have unspeakable feelings about influenza, so that when the new crown epidemic just spread, Americans paid far attention to it.
From the flu, we can clearly recognize the terrible nature of the source of the virus, and what is even more frightening is that the flu virus is only a kind of virus. So, how many types of viruses are there? Faced with this problem, the smallness of human beings is obvious.
On this ocean-dominated planet, a large number of viruses also depend on the ocean.
If the ocean is compared to a breeding ground for viruses, then the human body is its "parasite".
Scientific research has proved that many genes in the host may originate from viruses. If we look at the human genome, you will find that there are a large number of traces of viral genes, thousands of them. Take the continuation of human beings from generation to generation. Although most of the viral DNA in the human body is useless, our ancestors did "requisition" some viruses that are good for us. Without these viruses, we would not even be able to Born.
One hundred million years ago, the ancestors of mammals were infected with an endogenous retrovirus, which resulted in the earliest syncytin protein and the earliest placenta. Over millions of years, the ancestors of placental mammals have evolved several branches, and in the process of evolution they have been infected by other endogenous retroviruses. Some new viruses also carry a syncytin gene, and the encoded protein has better properties.
In the most recent moment in the history of evolution, viruses have contributed to the emergence of human beings. From this perspective, viruses are not only the destroyers of mankind, but also the source of our lives. The evolutionary history of our human beings is also the history of war between the human immune system and viruses.
The virus itself does not have the ability to survive alone, but once it enters the human body, it will aggressively attack human cells, destroy the normal DNA of the cells, and even directly attack the immune system. The well-known AIDS is caused by the human immunodeficiency virus (HIV). It can be said that while the virus helps us humans to evolve, it is also always ready to reveal its original fierce appearance.
In millions of years, viruses have been constantly evolving, constantly changing their structure. They are small enough, large enough, and fast enough to try their best to destroy the human immune system. Of course, we humans will never sit back and die. Our immune system will change its strategy to improve its combat capability according to the characteristics of the virus, and form an immune memory.
Regarding immune memory, we can simply understand it as resistance. When the offending virus is marked by our immune system, our immune system will have enough countermeasures to eliminate it when they come again next time. However, this is the case, the virus is always evolving like us. Each of their evolution may cost us a painful price. For example, the new crown virus we are now facing, if it were not strictly prevented and controlled by our country, what a terrible situation.
Now we truly understand that from the moment human beings were born, our immune system has been helping us resist viruses, and it has been the only means for humans to resist viruses for a long time. Therefore, we said in the previous course that one of the greatest inventions of modern medicine is the application of vaccines, which have helped us overcome many malignant infectious diseases caused by viruses. And the first time humans used vaccines to defeat the virus and save themselves, it was the battle against smallpox.
This is a great feat of mankind. In the past 3000 years, smallpox may have killed more people than any other disease on the planet. It wasn't until Edward Jenner, a British rural doctor, injected the extract of vaccinia pustules into the human body to achieve the initial smallpox immunotherapy. Since then, polio vaccines, rabies vaccines, measles vaccines, hepatitis B vaccines, etc. have come out one after another, allowing us humans to take a big step forward in preventing viral infectious diseases. And smallpox has gradually faded out of people’s vision because of the use of vaccines. No new cases of smallpox have been reported in the world for many years, and this is the first virus that humans have truly defeated, relying on our human population. Collective immunity to smallpox virus.
But this "long farewell" also tells humans that the threat of smallpox to humans cannot be completely erased. Our growing knowledge of the virus makes smallpox immortal in a sense. Because we live on a veritable "viral planet", there will be countless viruses that humans have never seen before. This is a long and eternal battle.
Mankind can only win a war against the virus if we continuously improve our own immune system.
Here, friends may wish to think about it, for you, strengthen physical exercise, maintain a balanced nutrition, establish a healthy lifestyle, do regular health checks, and scientifically and reasonably use immune boosters. Are these measures necessary?
In the next course, we will share with you the related content of immunity and tumor.
References:
https://sh.qq.com/a/20151105/021169.htm
https://baike.baidu.com/item/%E5%A4%A9%E8%8A%B1%E7%97%85%E6%AF%92/3111182?fr=aladdin
