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October 2003

This material was developed independently through an unrestricted educational grant from Trimeris.

The strongest, most effective medication in an HIV drug combination.

CD4 (T4) or CD4+ Cells
A type of T cell involved in protecting against viral, fungal and protozoal infections. These cells normally orchestrate the immune response, signaling other cells in the immune system to perform their special functions. Also known as T helper cells. A normal CD4 or T-cell count is between 800 and 1,200.

A measurement used to describe the concentration of cells in a cubic millimeter of fluid. This is the standard measurement for determining a person's CD4, or T-cell, count.

A family of HIV medications. Each class of HIV medications attempts to stop HIV at a different point in its reproductive cycle.

A measurement used to describe the concentration of a virus in a milliliter of fluid. This is the standard measurement for determining a person's HIV viral load level.

A molecule on the surface of a cell that HIV attaches itself to in order to begin the process of cell fusion.

Cross Resistance
Resistance that occurs for more than one drug at the same time. When HIV mutates, some of those mutations may prevent several medications from working correctly -- even medications that a person may never have taken before. When this happens, we say that the HIV has become cross resistant to those medications.

Deoxyribonucleic Acid (DNA)
The molecular chain found in genes within the nucleus of each cell, which carries the genetic information that enables cells to reproduce. DNA is the principal constituent of chromosomes, the structures that transmit hereditary characteristics.

How well something works. Often used when describing the strength of HIV medications and drug combinations.

A protein that causes a chemical reaction to take place.

The process in which HIV attaches to and combines with a CD4 cell.

A specific type of protein that has one end sticking out from the outer wall of a cell.

Immune System
The body's complicated natural defense against disruption caused by invading foreign agents (e.g., microbes, viruses).

The smallest particle of a compound that has all the chemical properties of that compound. Molecules are made up of two or more atoms, either of the same element or of two or more different elements. Ionic compounds, such as common salt, are made up not of molecules, but of ions arranged in a crystalline structure. Unlike ions, molecules carry no electrical charge. Molecules differ in size and molecular weight as well as in structure.

A genetic change. When HIV mutates, it can prevent HIV medications from working correctly; when this happens, we say that the HIV has become resistant to that medication.

Optimized Background
A type of combination drug regimen that has been specially chosen for a person so that it works as well as any drug combination can for him or her.

A fake pill. In many studies, researchers will give some people a placebo so they can measure how much better (or worse) people do when they are given the real medication. Placebos are usually nothing more than sugar pills.

Completely dissolved in a liquid.

The ability of HIV to reproduce itself despite the presence of HIV medications in the body. When HIV develops mutations, it can prevent HIV medications from working correctly; when this happens, we say that the HIV has become resistant to that medication.

Resistance Test
A medical test used to determine whether the HIV within a person is able to reproduce itself even if the person is taking medications designed to keep it from doing so.

Ribonucleic Acid (RNA)
A nucleic acid, found mostly in the cytoplasm of cells, important in the synthesis of proteins. The amount of RNA varies from cell to cell. RNA, like the structurally similar DNA, is a chain made up of subunits called nucleotides. In protein synthesis, messenger RNA replicates the DNA code for a protein and moves to sites in the cell called ribosomes. There, transfer RNA (tRNA) assembles amino acids to form the protein specified by the messenger RNA. Most forms of RNA (including messenger and transfer RNA) consist of a single nucleotide strand, but a few forms of viral RNA that function as carriers of genetic information (instead of DNA) are double-stranded. Some viruses, such as HIV, carry RNA instead of the more usual genetic material DNA.

On the surface; skin-deep.

The prevention of HIV's ability to reproduce itself.

This word usually appears when talking about medication side effects. A person is said to "tolerate" a drug if he or she doesn't experience any side effects severe enough to make them stop taking it, or if a person doesn't quit taking the drug because of the way it must be taken (e.g., by injection, or by swallowing a large number of pills several times a day).

Treatment Experienced
Used to describe a person who has already taken many of the available medications to treat a disease.

Treatment History
A detailed rundown of the previous medications a person has taken, as well as when those medications were taken, why they were stopped and any health problems a person experienced while taking them.

Treatment Naive
Used to describe a person who has never taken any of the available medications to treat a disease.

An HIV viral load that is so low it cannot be seen using existing viral load tests.

Viral Load
The amount of HIV in a person's blood. Monitoring a person's viral load is important because of the apparent correlation between the amount of virus in the blood and the severity of the disease: sicker patients generally have more virus than those with less advanced disease. A sensitive, rapid test -- called the viral load test for HIV-1 infection -- can be used to monitor the HIV viral burden. This procedure helps clinicians to decide when to give anti-HIV therapy. It may also help researchers determine more quickly if experimental HIV therapies are effective.


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This article was provided by TheBody. It is a part of the publication Fuzeon: A Review of the First Entry Inhibitor.