Viroids are DNA pieces without a nucleus and without a cell to provide it machinery to burn fuel to:
- break apart and rebuild molecules,
- move,
- eat and
- reproduce itself.
The average virus is about one one-hundredth the size of the average bacterium. Viruses are the most abundant biological entity on earth and their biomass exceeds the weight of all other living organisms combined. A teaspoon of seawater contains about one million viruses. Most of them are called bacteriophages destroying only bacteria in aquatic microbial communities and are harmless to fungi, plants and animals. There are millions of different types of viruses found in almost every ecosystem on Earth.
Viruses do not have their own metabolism, the power system to move, break down organic matter for energy and to use it to construct organic matter to grow.
Without this energy, they are like a capsule of medicine and cannot do anything more than float around, land on a cell and hopefully get absorbed.
Viruses, like seeds or tanks with empty gas tanks are helpless until anchored to a fertile cell to penetrate and inject their DNA and attach it to the cell DNA so that it can be copied many times over.
Once copied, the virus DNA is dressed in its protective layer and it emits an enzyme to break thru the cell`s wall and wait for another host.
Once copied, the virus DNA is dressed in its protective layer and it emits an enzyme to break thru the cell`s wall and wait for another host.
Like teenagers know too well, how the viruses are dress and their shapes are important deciding factors if the virus gets accepted or rejected by the cell it lands on. Like teenagers, viruses are extremely selective in the host cells they use. They usually choose only one type of host cell in one type of organism, leaving all other cells and organisms alone.
How dangerous and contagious a virus is depends on how long it can keep from disintegrating in the environment. It is like a spark. If there are enough sparks that last long enough in an enough vulnerable environment, then it is going to burn out of control until the host can no longer sneeze it out on someone else.
A healthy immune system can cope with sparks that we are continually bombarded with, just like a healthy forest is capable of surviving the worst of thunderstorms.
The shapes of viruses are simple helical and icosahedral forms that make spindle-shaped structures and hooked rods, teardrops, bottles and even more complex structures.
Enterobacteria phage T4 has an icosahedral head bound to a helical tail with a hexagonal base plate with protruding protein tail fibers. This tail structure acts like a molecular syringe, attaching to the bacterial host and then injecting the viral genome into the cell much like a mosquito does when it sucks out your blood.
Helical viruses form a helical structure, with a central cavity or hollow tube.
Most viruses choosing animal host cells are icosahedral or near spherical with icosahedral symmetry. A regular icosahedron is the optimum way of forming a closed shell from identical subnits.
Some species of virus like influenza and HIV are like spies. They envelop themselves in a modified form of one of the cell membranes to avoid detection and to gain entrance to the host. HIV evades the immune system by constantly changing the amino acid sequence of the proteins on its surface, just like computer viruses do.
If they land on a cell which does not recognize them to get rid of them, that cell has no immunity for these viruses, the viroids get absorbed into the host, and as if waking up from a long sleep, they start to get a life.
They use the energy and machinery of the host to make multiple copies of their viroid and to dress them up in full armor with protein coats and in a process called “lysis” break thru the host cell greatly damaging it in the process eventually killing it. When too many cells get killed this way, and they all belong to one organism, then the virus ends up killing the host organism.
Examples of common human diseases caused by viruses include the common cold, influenza,
chickenpox and cold sores.
Some viruses as if hibernating, cause no apparent changes to the infected cell. Cells in which the inactive virus is latent or dormant for many months show few signs of infection and often function normally as is often the case with herpes viruses.
Some viruses such as Epstein-Barr virus can cause cells to proliferate without causing malignancy, while others, such as papilloma viruses, are established causes of cancer.
Many serious diseases such as Ebola, AIDS, avian influenza and SARS are caused by viruses.
Some viruses can cause life-long or chronic infections, where the viruses continue to replicate in the body despite the host's defense mechanisms. This is common in hepatitis B virus and hepatitis C virus infections.
People chronically infected are known as carriers, as they serve as reservoirs of infectious virus. In populations with a high proportion of carriers, the disease is said to be endemic. When outbreaks cause an unusually high proportion of cases in a population, community or region they are called epidemics. If outbreaks spread worldwide they are called pandemics.
Because viruses take cells as hostage, they are difficult to eliminate without damaging the host cells themselves. Vaccinations, whether given naturally to babies by house pets, or injection by needles provide immunity to infection. Damaged and weakened strains of the virus are used in manageable amounts to train the cell to defend itself by being able to recognizes the virus and act accordingly on time.
Antiviral drugs which selectively interfere with viral replication can be used as protection against certain virus outbreaks.
Plants have elaborate and effective defense mechanisms against viruses. One of the most effective is sacrificing cells around those already infected isolating the virus which needs live cells to reproduce and stops the infection from spreading. This is seen as large spots. This stops the infection from spreading.
Animals rely on plants to live and plants rely on the bacteria. Bacteria do not rely on any organism and without the virus to keep bacteria in check, bacteria would overwhelm nature and drown out all other organisms. Fortunately most viruses co-exist harmlessly in their host and cause no signs or symptoms of disease,
the organism’s immune system offers an effective protection against viruses, and most viruses chose bacteria as their host of choice.
Some viruses as if hibernating, cause no apparent changes to the infected cell. Cells in which the inactive virus is latent or dormant for many months show few signs of infection and often function normally as is often the case with herpes viruses.
Some viruses such as Epstein-Barr virus can cause cells to proliferate without causing malignancy, while others, such as papilloma viruses, are established causes of cancer.
Many serious diseases such as Ebola, AIDS, avian influenza and SARS are caused by viruses.
Some viruses can cause life-long or chronic infections, where the viruses continue to replicate in the body despite the host's defense mechanisms. This is common in hepatitis B virus and hepatitis C virus infections.
People chronically infected are known as carriers, as they serve as reservoirs of infectious virus. In populations with a high proportion of carriers, the disease is said to be endemic. When outbreaks cause an unusually high proportion of cases in a population, community or region they are called epidemics. If outbreaks spread worldwide they are called pandemics.
Because viruses take cells as hostage, they are difficult to eliminate without damaging the host cells themselves. Vaccinations, whether given naturally to babies by house pets, or injection by needles provide immunity to infection. Damaged and weakened strains of the virus are used in manageable amounts to train the cell to defend itself by being able to recognizes the virus and act accordingly on time.
Antiviral drugs which selectively interfere with viral replication can be used as protection against certain virus outbreaks.
Plants have elaborate and effective defense mechanisms against viruses. One of the most effective is sacrificing cells around those already infected isolating the virus which needs live cells to reproduce and stops the infection from spreading. This is seen as large spots. This stops the infection from spreading.
Animals rely on plants to live and plants rely on the bacteria. Bacteria do not rely on any organism and without the virus to keep bacteria in check, bacteria would overwhelm nature and drown out all other organisms. Fortunately most viruses co-exist harmlessly in their host and cause no signs or symptoms of disease,
the organism’s immune system offers an effective protection against viruses, and most viruses chose bacteria as their host of choice.
Thanks to viruses, we live in the beautifully balanced nature we experience.
THE END
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