The Human Immunodeficiency Virus (HIV) belongs to a class of viruses known as the retroviruses. These viruses are known as RNA viruses because they have RNA as their basic genetic material instead of DNA. The retroviruses are unable to replicate outside of living host cells, because they contain only RNA. However, they have the enzyme reverse transcriptase that can make DNA from the RNA and allow them to integrate into the host cell genome. The retroviruses are composed of three subgroups, two of which are pathogenic to humans. They are the oncarnovirus subgroup and the lentivirus (meaning, slow virus) subgroup. The Human Immunodeficiency Virus, which belongs to the lentivirus subgroup, is further divided into two types based on the diseases they produce. The HIV-1 produces the acquired immunodeficiency syndrome (AIDS), while the HIV-2 produces a similar disease that is at present, largely...