Health and disease: Understanding virus and their functions

According to Wikipedia, the word virus is derived from Latin and it means toxin or poison. The virus can't grow or reproduce without a host cell such as the human cell or the monkey cell. Therefore, it doesn't live outside of the body. You would not get it from touching things or articles like clothing. By the time it's outside, it's no longer alive. Viruses have the ability to infect all cellular organisms and this is all human and all animals.

Martinus Beijerinck first discovered the tobacco mosaic virus in 1899. Now there are as much as 5000 different types of virus found. You can study virology from majoring in microbiology. Virus is an interesting topic because it's very stubborn and causes a lot of death in human. Currently we are seeking a vaccine for the HIV virus but we haven't come across a plan yet.

Viruses are like human they have genes that is consisted of DNA or RNA. They too have genetic information. They also have a protein coat as a protective layer. Viruses also have a fat coat when they are outside a cell. The have the shape of a simple helical and icosahedral. They do come in more complex structures. It's 100 times smaller than bacteria. They don't know the exact origin of viruses but rumor is that they evolved from plasmids which are free piece of DNA that can move around cells. They also evolve from bacteria.
How do viruses spread? They spread differently in plants, animals and human. In plants the virus is spread by the insects that eats the plants. Blood sucking insects spread the virus in animals. In human , it's spread via intercourse like the HIV virus. These insects that carry viruses are called vectors. You can catch the influenza virus from the sneezing and coughing of someone else. Norovirus is transmitted by the fecal-oral route, when they contaminate hands, food or water. The Rotavirus is spread by direct contact with infected children.  Viruses can be harmless in some cases and harmful in other. It all depends on the type of the virus and the host. HIV virus is the harmful one and it could cost life long infections and replication. The interesting thing is that virus doesn't have a fatal effect on animals.

When an animal is confronted with a virus, the animal give off an immune response which can terminate the virus's life. The animal immune responses is the same as a vaccines that give lifelong immunity to the virus. Another interesting thing is that bacteria can even attack virus better than human. You will find no use with antibiotics but with only antiviral. If you want to prevent the spread of virus, you should avoid insects, flyes, mosquitoes, unprotected sex, fecal matter, being around sick people, and blood substances. Viruses can cause life threating diseases like HIV virus.

Source: http://www.wikipedia.com/virus