Viruses are not dangerous to people, yet they cause disease. They multiply by replicating themselves and then they multiply again, continually sending the DNA they form into the bloodstream of every person. Some viruses cause disease in humans, animals and other animals, but others are harmless to humans. The most common viral diseases are: hepatitis B, hepatitis C, Epstein-Barr, viral encephalitis (inflammation of the brain and spinal cord), viral meningitis (inflammation of the head and neck), herpes (herpes simplex virus) and shingles (necrosis virus). There are many other kinds of viruses, some of which are dangerous to human beings and some of which are not.
Scientists estimate that viruses outnumbers bacteria by a factor of 10 to one. Since viruses do not have the same parts as bacteria, neither can they be destroyed by antibiotics; only certain vaccines or antiviral drugs can eliminate or lower the severity of other viral infections, such as AIDS, lymphoma and chronic bacterial infections. There are millions of different kinds of viruses. Some viruses cause diseases, and other viruses are dangerous to humans, animals and other organisms. A virus can replicate itself many times over, and this makes it hard to kill.
Since a virus is a living cell, it can cause problems when it enters living cells in your body. A virus that enters through your skin as acne, for example, has a chance of causing problems with your immune system if it ingests nutrients from your blood stream and uses them to replicate itself. The same is true for a virus that enters through a cut or scratch in your skin as a chickenpox virus. These viruses are alive.
Some viruses may be part of our own cells and reproduce by secreting proteins, building protein chains, or larger structures into the outer membrane of the cell. The protein produced is often a waste product, making the virus harmless to the host cell. These are the type of viruses that you get on your hands, and they spread by contact. However, some viruses may also cause illness or even death. Examples include the SARS virus, which is responsible for the deadly SARS outbreak in recent years.
Other viruses may affect the genetic makeup of the host cell. This is especially common in bacteriophages, which are a class of viruses that attack and eat the host cell’s DNA. The result is a strand of DNA with no letters left in it (a chromosome) – and sometimes, the chromosome can insert itself into the open cellular space, creating a cyst. These cysts grow into cancerous tumors.
Bacterial and viral agents that infect living cells can potentially cause all types of disease. To protect against viral, chemical and other biological hazards, we have developed a highly specific set of DNA-binding proteins called rna genes. These genes, which cannot take on human DNA, block the entrance of foreign viruses and bacteria into the host cell. They make it very difficult for any viruses to infect the cells of any kind.