Business Social December 2nd - Under the electron microscope, filamentous groups of H1N1 influenza viruses freely float between highly concentrated culture solutions.
This spring, an epidemic first occurred in Mexico. Local scientists discovered a shocking fact in the laboratory: a new type of flu virus had emerged in the human world —— the new H1N1.
Subsequently, scientists continued to track it, trying to unravel the mystery of its origin.
Continuation of a Powerful Virus?
American experts have found that this H1N1 virus is highly similar to the Spanish flu virus that once severely affected human society.
Regarding the origins of this H1N1 virus, scientists from various countries are still debating endlessly.
Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, among others, stated after studying the virus that all currently known human-infecting H1 influenza viruses are descendants of the "Spanish flu" pandemic H1N1 virus.
They found that this virus bears a high degree of similarity to the "Spanish flu" virus.
"At that time, this virus suddenly appeared in the United States when people were completely unprepared. Within 25 months, it left behind 50 million bodies among humans, then disappeared inexplicably," said a domestic virologist.
In the memory of Americans, this was a huge trauma, showing immense destructiveness from 1918-1919. Ten percent of the workforce was bedridden.
At that time, human movement was still limited to slow transportation like ships and trains. However, the virus spread across the globe in less than five months.
Moreover, nearly half of those who died from the "Spanish flu" were young adults in their prime twenties and thirties. This characteristic is identical to the current H1N1 flu. Unlike other seasonal flus, it does not just kill the elderly or those with weakened immunity.
On May 7th, the independent research group in the UK published their study results on the circulating strain of this pandemic in the New England Journal of Medicine.
They collected samples from 11 sporadic cases of H1N1 influenza, and the study showed that these viruses were a new strain mixed with human, avian, and swine flu viruses.
An expert from the Ministry of Health said that such a rare combination is difficult to achieve in nature, so many scientists believe that the H1N1 virus came from a human laboratory, where technicians can combine any few viruses together.
Based on this, the New England Journal of Medicine concluded: "The current situation is not the return of the 1918 (virus), but the continuation of the 1918 (virus)."
A Fierce Monster
Spherical influenza viruses have over 700 tentacles, which tear through human red blood cells for self-replication.
In the eyes of medical experts, the influenza virus resembles a bullet.
It quickly spreads throughout the respiratory system upon entering the human body. Individual spherical virus cells fly at high speed within the body while searching for the host cells they need.
These spherical viruses are protected by a tough armor composed of proteins and fats. The armor has two layers, one of which is almost entirely made up of cholesterol.
All genetic material of the virus is hidden inside this sphere.
Those long single-stranded ribonucleic acids (RNA) genetic materials, like the plastic tubes we use, are tangled together to form a helical structure. Five such tubes are intertwined with protective proteins to form genetic packages, also called chromosomes, which contain all the information of the virus.
These spherical viruses don't look cute; each sphere has over seven hundred tentacles, like long rods, fiercely protruding outwards. These tentacles are proteins, one of which is the familiar H, also known as hemagglutinin, and the other tentacle is N, namely neuraminidase.
Without these two types of tentacles, the virus would be unable to infect or destroy cells.
Inside the human body, they mainly attack red blood cells.
During the attack, the long hemagglutinin protein (H) is responsible for firmly grabbing red blood cells, enabling the connection between the two cells. Neuraminidase (N) breaks down sialic acid (a sugar molecule) on the cell membrane.
After tearing off the cell membrane, the virus's genetic package enters the nucleus of the red blood cell and continuously replicates itself.
Influenza viruses have excellent reproductive capabilities. From the initial attachment of a virus to a cell until the cell releases new viruses, it takes about a dozen hours, sometimes even shorter, but rarely more.
Afterward, hundreds of thousands to millions of new influenza viruses will "swarm" out of the cell.
John Barry wrote in "The Great Influenza": About 99% of the newly released viruses may be too defective to infect other cells again, but approximately 1,000-10,000 viruses remain infectious.
Viruses Are Also Constrained by "Military Rules"
The tentacles used to destroy cells are also susceptible to immune system attacks, so the virus cell's tentacles undergo mutations for survival.
Any virus must be constrained by something akin to "Catch-22."
It must possess the two proteins "H" and "N" to destroy cells, and it is precisely these two proteins that trigger the immune system to launch an attack.
When antibodies against the virus are produced in the human body, they can direct the immune system to recognize "H" and "N", then initiate other cells to engulf them.
However, viruses can also mutate.
When the virus replicates, the chromosome needs to unfold and replicate its proteins and RNA according to the original pattern. During this process, some parts of one chromosome may overlap with another, such as avian influenza virus, swine influenza virus, etc.
Therefore, after replication, a new virus different from the original one appears. After the virus mutates, the "H" and "N" tentacles will also change. If the changes are small, the antibodies in the human body can still recognize and attack them.
"If they undergo major mutations, the immune system cannot identify them," said Guo Yuanji, former director of the National Influenza Institute of the Chinese Center for Disease Control and Prevention.
He is one of the earliest researchers of influenza viruses in China.
He said that therefore virologists classify influenza viruses further based on the mutation conditions of these two proteins and assign them different numbers.
The H protein has 16 subtypes, and the N protein has 9 subtypes. There can be 144 possible combinations of HN in influenza viruses. However, only three combinations —— H1N1, H2N2, and H3N2 —— have the ability to infect humans.
Other combinations, such as the H5N1 avian influenza virus, occasionally transmit to humans but essentially remain avian influenza viruses.
People collectively refer to influenza viruses that can cause infections and diseases in both humans and animals as Type A influenza viruses.