envelope protein that binds to CD-4 molecules. CD-4 molecules are most commonly found in human T-cells. (HIV Graphics)The entire life of a retrovirus consists of infecting cells to replicate new viruses. When a virus has no available cells to infect, it remains dormant. It can survive for great amounts of time in this dormant state. When the virus comes into contact with new living matter, it activates and again begins to replicate.Many types of retroviruses are known today. Undoubtedly the best known is the HIV virus, the virus that causes AIDS. The name for the family that both HIV-1 and HIV-2 belong to is the lentivirus family. A retrovirus known as HTLV-1 or HTLV-2 (human T-cell lymphotropic virus) along with a virus deemed BLV both belong to the family BLV-HTLV.When a retrovirus infects a host cell it must first find a cell with a match for in its surface proteins. After the virus has attached itself to the side of the host cell, it injects both the viral RNA and several copies of the enzyme reverse transcriptase. (Retropages) Without this vital enzyme, the viral RNA would be essentially useless. Reverse transcriptase is "a DNA polymerase that uses RNA as its template." In other words, the enzyme allows genetic information to flow in reverse from the normal. DNA is usually transcribed into RNA; reverse transcriptase allows just the opposite to take place. When the reverse transcriptase is attached to the viral RNA is synthesizes many DNA copies of the RNA. Some of these copies are randomly inserted into the host's chromosome's DNA. This modifies and changes the blueprint orders contained in the host cells DNA. The remaining copies of this DNA are transcribed into fresh RNA molecules. Each different gene is translated into a different part of a new retrovirus. A gene called the gag gene is translated into a capsid protein. The pol gene is transcribed into reverse transcriptase and the env gene is translated into th...
