Virus: the more you understand, the more confused

  From birth to death, we have been with the virus all the time, but most people have almost never seen these creatures that have been with us for the longest time. The virus has always been covered with a veil of mystery. What’s even stranger is that the more we know about the creatures that cannot live independently and must be parasitic in other organisms, the more we are confused.
How much do you know about virus types

  Viruses may be the most abundant and important creatures on the planet. They are almost everywhere, from the oceans and forests to the air you breathe, and even in your body, they are constantly replicating and growing. The number of viruses may far exceed the stars in the sky. We estimate that the number of stars in the universe is about 1024. A paper in 2015 stated that about 800 million viruses are attached to every square meter of the earth’s surface every day. The surface area is 510 million square kilometers, which means that there are about 1023 kinds of viruses on the earth in one day. This is just the number of “viruses” we know, but in fact, the types of viruses we know are still very few.
  In 2019, many scientists “filtered” viruses out of the ocean, and then compared the DNA sequence of the virus with the DNA sequence of known species through DNA sequencing, and found 195,728 new viruses, which is higher than in 2015. We know about 20 times more types of viruses.
  Even if 200,000 viruses have been discovered, it may still be the tip of the iceberg, because the research methods used can only find DNA viruses (viruses that use DNA as genetic material). Those viruses that we are familiar with and have great lethality, such as HIV, influenza virus, coronavirus, etc., are all viruses that use RNA as genetic material. We have no way to estimate how many types of these viruses are.
  The virus does not only live in the ocean. A 2017 study provided the first distribution map of all virus types we currently know. In addition to the ocean, the author also counted the number of viruses in 7 ecological environments, including hot springs, shallow ground, polar regions, sewage, fresh water, and saline-alkali land. The results show that the ocean is indeed the most favorite living environment for viruses, but the number of viruses in polar regions, sewage and freshwater is not inferior, and many kinds of viruses can survive in different environments.
  The distribution of viruses knows no borders. To understand all members of the virus family, global cooperation is necessary. Scientists from the Institute of Health at the University of California, Davis proposed a global virus group plan in 2018. Scientists from 35 countries have joined the plan, and they share all the new discoveries of the virus. Based on current data, scientists estimate that 1.6 million viruses have not been discovered. Among these viruses, it is estimated that 650,000 to 840,000 viruses can infect humans and cause human diseases.
New coup to fight the virus

  Of course, searching for viruses is not only to find the virus itself, but the more important purpose is to understand the virus in advance, find unknown viruses that may infect humans, block their spread, and prevent problems before they occur. But we know that viruses have a characteristic, that is, they mutate very fast. Some viruses themselves do not infect humans, but once they mutate, they may gain the ability to infect humans, or after mutated, their lethality will be greatly improved, etc. . In a situation like this, prevention alone is not enough. We have to find ways to kill the virus.
  At present, the most commonly used types of antiviral drugs in clinical practice are the anti-influenza virus drug oseltamivir, the anti-AIDS drug zilavudine, and the anti-herpes virus drug ganciclovir. After the virus enters the host cell, it “cuts” the host’s genome and “sews” its own genetic material into the host’s genome, so that when the host replicates itself, it will replicate a lot of viruses. The antiviral drugs are precisely the protease “scissors” that specifically inhibit the virus. They can make the virus unable to “cut open” the host genome and ride on the host’s self-replicating “hit ride”, which greatly inhibits the virus’s ability to replicate wildly.

The distribution of viruses in the seven environments:
the longer the arc length, the greater the number of virus types in the habitat.

  Although antiviral drugs can inhibit the “scissors” of the virus, as a “professional parasite”, the virus will not wait to die. It will continue to mutate and upgrade the “scissors”. After the new “scissors” are created, the original drugs are ineffective against it. This is why some patients have been taking anti-AIDS drugs for many years, but still cannot cure AIDS and even eventually die. Recently, researchers at the University of California, San Diego School of Medicine have found a new way to fight HIV. They discovered that there is a type of RNA in humans that is an accomplice to help the HIV resurrection and upgrade the “scissors”. If this RNA is eliminated , HIV will dormant and can no longer replicate in the human body.
  In addition to blocking replication, setting a trap to block the virus has also become the idea for researchers to make antiviral drugs. Using this idea, scientists from the University of Manchester in the United Kingdom, the University of Geneva in Switzerland and the Swiss Federal Institute of Technology in Lausanne have developed a New broad-spectrum antiviral drugs. They use cyclodextrin (a small molecule of glucose) as a drug body to attract the virus, and then the drug will completely surround the virus, tear the protein shell of the virus, and destroy the virus. In animal experiments, this drug has shown strong lethality against herpes virus, HIV, hepatitis C virus and Zika virus.
The other side of the virus

  Although we now hate the virus deeply and can’t wait to get rid of it, but in fact, if there is no virus on the earth, perhaps human beings will not exist.
  A long time ago, the virus originally lived independently, but after it “combined” with cyanobacteria, it was happier than “single”, so the virus gave up the ability to live independently and its offspring became “parasites.” It is precisely because of the “combination” of viruses and cyanobacteria that today’s rich and colorful life on earth was born.
  There is a basis for this idea. In 2004, scientists discovered some genes in the genome of a virus called Mimivirus that repair DNA and regulate RNA translation proteins. This means that the virus can replicate itself and may have the ability to survive independently. Scientists compared the genome of the virus with other organisms and found that the “family tree” of the virus is very long. It can be traced back to 3.3 billion years ago. At that time, there were only three types of archaea, bacteria and simple eukaryotes on the earth. Still a “bachelor”.
  The earliest “original match” of the virus is cyanobacteria. Cyanobacteria are prokaryotic organisms that do not have chloroplasts but can carry out photosynthesis. They are also the first organisms to carry out photosynthesis and release oxygen. It is said that a quarter of the oxygen on the earth is produced by cyanobacteria. Without cyanobacteria, the early aerobic organisms on the earth, including the ancestors of humans, would not have appeared. The reason why cyanobacteria can carry out photosynthesis is the virus.
  In 2003, the microbiologist Martha Krocky of the University of Leicester in the United Kingdom found a gene called PSBA in the cyanobacteria. It is a gene necessary for the photosynthesis of the cyanobacteria. This gene is likely to be derived from a virus. Croki first performed gene editing on the cyanobacteria and turned off the PSBA gene, so that the cyanobacteria lost the ability to carry out photosynthesis. After that, he used cyanobacteria virus to infect cyanobacteria and found that cyanobacteria can perform photosynthesis again, and the photosynthesis efficiency of virus-infected cyanobacteria is higher than that of uninfected normal cyanobacteria.
  In addition to “bringing” life, the virus has also done another good thing, which is to kill bacteria that are harmful to humans. Viruses that can kill disease-causing bacteria-After bacteriophages infect bacteria, they will communicate with each other through a polypeptide composed of several amino acids, and “discuss tactics” to determine how to destroy the immune defense line of the bacteria and attack the bacteria. Biologists Basler and Silpe of Princeton University in the United States found a phage that could only attack Vibrio cholerae. They modified the phage’s peptides and expanded their “friend circle”. Now this phage is new. Knowing the two bacteria, Escherichia coli and Salmonella typhimurium, they can also discuss “tactics” against these two bacteria. If we can master the technology to modify phages, they will become new and powerful “antibiotics.”
  Not only to kill pathogenic bacteria, but many scientists have discovered that viruses can even help us kill cancer cells. An oncolytic virus called enadenotucirev has been used in clinical trials to treat pancreatic cancer, colon cancer, lung cancer, Breast cancer, ovarian cancer and prostate cancer and other cancers.
  Just as there are intertwined and complex food webs in the biological world, if any link in the food web is eliminated, the food web may be destroyed, and the entire ecosystem may collapse. If the virus is completely eliminated, the bad bacteria will also lose control and cause humans. Many hazards. So, please let go of your prejudice against viruses, don’t “scream and kill” all viruses, learn to live with some of them.