Aids

Aids first appeared in 1959. Its definition states that its any of a group of retroviruses and esp. HIV-1 that infect and destroy helper T cells of the immune system causing the marked reduction in their numbers that is diagnostic of AIDS -- called also AIDS virus, human immunodeficiency virus. A retrovirus is any of a group of RNA-containing viruses (as HIV) that produce reverse transcriptase by means of which DNA is produced using their RNA as a template and incorporated into the genome of infected cells and that include numerous tumorigenic viruses. During the 2000 year 5.3 million peop…