Seven coronaviruses can affect humans, but each one can change or mutate, producing many variants. Learn more about coronaviruses here. Just as there are friendly bacteria in the intestines that are essential to gut health , humans may also carry friendly viruses that help protect against dangerous bacteria, including Escherichia coli.
Viruses do not leave fossil remains, so they are difficult to trace through time. Scientists use molecular techniques to compare the DNA and RNA of viruses and find out more about where they come from.
Three competing theories try to explain the origin of viruses. In reality, viruses may have evolved in any of these ways. The regressive, or reduction, hypothesis suggests that viruses started as independent biological entities that became parasites. Over time, they shed genes that did not help them parasitize, and became entirely dependent on the cells they inhabit. In this way, they gained the ability to become independent and move between cells. The virus-first hypothesis suggests that viruses evolved from complex molecules of nucleic acid and proteins either before or at the same time as the first cells on Earth appeared, billions of years ago.
When a viral disease emerges, it is not always clear where it comes from. A virus exists only to reproduce. When it reproduces, particles spread to new cells and new hosts. The features of a virus affect its ability to spread. Some viruses can remain active on an object for some time. If a person with the virus on their hands touches an item, the next person can pick up that virus by touching the same object. The object is known as a fomite.
Viruses often change over time. Some of these changes are very small and do not cause concern, but others can be more significant. Significant changes could make a virus more transmissible, as has been the case with the B.
They may also help the virus evade the immune system or existing treatments. For example, doctors use several drugs in combination to treat HIV so that it is harder for the virus to develop resistance to treatment.
Influenza viruses can also do so-called antigenic shift. This can happen if a host cell has become infected with two different types of influenza virus.
For instance, pigs can often serve as a mixing vessel for avian and human influenza viruses. Some viruses, such as HPV, can lead to cancer. The full impact of a virus can take time to appear, and sometimes there may be a secondary effect. For example, the herpes zoster virus can cause chickenpox. The person recovers, but the virus may stay in the body. Years later, it may cause shingles in the same individual. Coronaviruses are a large family of viruses and include viruses that cause the common cold.
However, it has changed many times since scientists first identified it in China. By September , scientists had logged over 12, mutations, and the development continues. Some variants are more transmissible and more likely to cause severe illness than others. The main concern with new variants is the unpredictability of their impact.
The main symptoms of COVID are dry cough , fatigue , and fever, but there are many possible symptoms. Anyone who has symptoms should seek a test. It is also important to self-isolate until 10 days after symptoms appear and when no fever has been present for 24 hours. Researchers have shown that just living with someone will lead to rapid sharing of the viruses in your body. Ultimately, we need to know what all these viruses in the human body are doing, and figure out whether we can take advantage of our virome to promote our health.
It may seem counterintuitive, but harming our bacteria can be harmful to our health. For example, when our healthy bacterial communities are disturbed by antibiotic use, other microbial bad guys, also called pathogens, take advantage of the opportunity to invade our body and make us sick. Thus, in a number of human conditions, our healthy bacteria play important roles in preventing pathogen intrusion. So the race is on to find those viruses in our viromes that have already figured out how to protect us from the bad guys, while leaving the good bacteria intact.
Indeed, there are recent anecdotal examples utilizing phages successfully to treat life-threatening infections from bacteria resistant to most if not all available antibiotics — a treatment known as phage therapy. Unfortunately, these treatments are and will continue to be hampered by inadequate information on how phages behave in the human body and the unforeseen consequences their introduction may have on the human host.
Thus, phage therapy remains heavily regulated. At the current pace of research, it may be many years before phages are used routinely as anti-infective treatments. But make no mistake about it; the viruses that have evolved with us for so many years are not only part of our past, but will play a significant role in the future of human health.
Read the original article here. David Pride and Chandrabali Ghose. Transmission electron micrograph of multiple bacteriophages attached to a bacterial cell wall. Viruses are extremely tiny parasites made of genetic material, wrapped in proteins and sometimes an outer membrane layer, which hijack living cells to reproduce themselves. The first stages of an infection happen when a virus gets past our physical barriers of skin and mucus, and enters a suitable cell.
Once inside, a virus can take over the cell, forcing the cell to make many copies of the virus replicate , which damages the cell and sometimes kills it. The newly-made viruses are released to find a new cell.
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