MYTH:

Viruses get stronger by infecting each other, and stronger viruses
will kill the weaker ones.

TRUTH:

Viruses only infect living cells.

Think of a single virus particle as an envelope that contains a set of instructions on how to make hundreds or thousands of identical copies of itself. Other than this set of instructions, the virus particle contains none of the materials or tools needed to make more viruses. The materials and tools needed to "read" these instructions and make more virus particles only exist within living cells. So the virus needs to get inside of a living cell so that it can use the inner machinery of the cell to make new viruses.

The process called "infection" is the way a virus finds the right cell and gets inside. From the virus's point of view, the cell is also known as a "host cell." If a virus particle does not find and infect its specific host cell, then no new viruses are made. Everything a virus needs to make more of itself exists only within its host cell.

MYTH:

A single virus can infect any living thing that it comes in contact with.

TRUTH:

More often than not a virus can only infect a single host species.

Because a virus is completely dependent on its host cell, the set of instructions on how to make more virus particles is very specific. Thus, it is very important to the virus that it finds only its host cell because if it infects the wrong host cell, no new virus particles will be made.

To make sure it has the right host cell, viruses carry specific molecules on the outside of the virus particle called "attachment proteins." The attachment proteins recognize specific molecules called "receptors" on the outer surface of the host cell. Each virus is looking for only one specific receptor that fits its attachment protein.  So think of the attachment protein as the key and the receptor as the lock. Just like your house key only fits into and unlocks your door; a virus’s attachment protein only fits on the specific receptor of its host cell. Once the attachment protein has joined its specific receptor, the virus is allowed into the host cell. The door to the inside of the cell opens.

Once inside the host cell, a virus can take over and use the biological machinery of the host cell to make more copies of itself. Each virus type infects only one type of host cell because the instruction set for making a new virus can only be read by specific types of cells; and because attachment proteins are like a specific key looking for a specific lock.  For these reasons, viruses that infect tulips, your pet hamster, or a bacteria cannot infect you. 

MYTH:

Viruses are only present in dirty places.

TRUTH:

Viruses are nearly everywhere.

Viruses were discovered about 110 years ago and determined to be disease-causing microbes that were smaller than bacteria. For 90 years after the discovery of the first virus, we believed that viruses were rare in the places where most microbes live, such as soil and seawater. Then about 20 years ago, two groups of marine biologists discovered that viruses are actually the most abundant microorganisms in the sea.  We now know that a single drop of seawater from the ocean contains around 10 million virus particles, and a single pinch of soil from your backyard contains around 100 million virus particles. 

A two-liter soda bottle full of seawater contains more viruses than there are human beings on the Earth. Indeed, everywhere we’ve looked for viruses, from the deep-sea hydrothermal vents to the soils of Antarctica and Delaware, we’ve found lots and lots of viruses. Scientists estimate that if we were able to count all of the viruses in the ocean and in the soils that cover the Earth, the number would be 10,000,000,000,000,000,000,000,000,000,000.  This number is a 1 with 31 zeros behind it! There are currently around 6,700,000,000 people on Earth, so we are way outnumbered by viruses.

But don’t be grossed out by our viral infested world.  Nearly all of these viruses infect only bacteria and are harmless to us.

MYTH:

Most of the viruses in nature infect plants, and animals

TRUTH:

Most viruses in nature infect bacteria and are harmless to plants and animals.

In the places where we find most viruses, like soil and water, bacteria are the most numerous life forms. In fact, bacteria are almost as numerous as viruses on planet Earth.  There are 1,000,000,000,000,000,000,000,000,000,000 bacterial cells on Earth. 

This number is a 1 with 30 zeros behind it. If we divide the number of viruses on Earth by the number of bacteria on Earth there are 10 viruses for each bacterial cell on planet Earth. Because bacteria are so numerous, it only makes sense that viruses infecting bacteria are the most common sorts of viruses in nature.  Viruses which infect only bacteria are called bacteriophages (back-tear-ee-o-fae-ges), and these are the sorts of viruses we study when we explore places like the deep-sea hydrothermal vents.

MYTH:

Antibiotics kill viruses and can cure viral infections like the common cold.

TRUTH:

Antibiotics only kill bacteria and cannot cure viral infections.

The term "antibiotics" is a name for a big group of drugs that are capable of killing bacteria. These drugs work by wrecking the inner biological machinery of the bacterial cell. Some antibiotics prevent the bacterial cell from making protein. A bacterial cell that cannot make protein will quickly die. Other antibiotics cause the outer cell wall of the bacteria to become weak and eventually break. Once the cell wall breaks, the bacterial cell dies.  Because viruses do not have any biological machinery of their own, antibiotics are completely harmless to viruses. 

Drugs that kill viruses are known as "antivirals."  It is often more difficult to discover antiviral drugs to fight viral diseases of humans. This is because viruses use our own cells to make copies of themselves. If we are to kill the virus, we have to kill the infected host cells which are making viruses. An alternative is to find drugs that disable the virus particles themselves and prevent them from infecting our cells. This is also very difficult.

While a virus infection like the common cold or a sore throat is certainly no fun, our bodies are usually able fight off these viral diseases in a few days to a week. However, there are other viruses that our bodies cannot fight off. These viruses cause very serious diseases such as polio and hepatitis, which can cause long-term illness or worse. Fortunately, we can easily defend ourselves against these dangerous viral diseases by getting vaccinated against each of these viruses.

A vaccine contains a very small piece of the bad virus. From this small piece, our body learns how to fight the whole virus. Within a week or two after getting a vaccine our body is ready to eliminate the disease-causing virus if it tries to infect us. For some viruses, this defense system can last our whole life; for other viruses we may need an occasional boost of vaccine. In the case of the flu virus, each year a new vaccine is made to fight against the particular strain of flu that will be causing people to get sick over the coming flu season.