Glossary of terms

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• R5-Tropic Virus
• Also known as M-tropic virus. A strain of HIV that uses the chemokine receptor CCR5 as a co-receptor to bind to and infect human cells. HIV is usually R5 tropic early on in infection, but the virus can switch to using a different co-receptor as the disease progresses. See also: X4-Tropic Virus, CCR5, Co-Receptor.
• Randomized Trial
• A type of clinical trial in which participants are assigned by chance to one of two or more treatment or placebo groups. A randomized trial design helps researchers gather meaningful information and make valid statistical calculations. See also: Clinical Trial, Placebo.
• Rapid Test
• A type of HIV-1 ELISA test that can detect antibodies to HIV in the blood in less than 30 minutes with greater than 99% sensitivity and specificity. A positive rapid test result should be confirmed by an HIV Western blot test. See also: Enzyme-Linked Immunosorbent Assay, Western Blot.
• Rebound
• See: Viral Rebound.
• Receptor
• A protein on the surface of a cell that serves as a binding site for substances outside the cell, such as HIV floating free in the blood. See also: Co-Receptor, CD4 Receptor.
• Recombinant
• Produced by genetic engineering. Also refers to a new organism or compound produced by inserting the genetic material of one organism into the genetic material of another organism. See also: Genetic Engineering.
• Refractory
• Refers to a disease or condition that has gotten worse despite treatment.
• Remission
• The period during which symptoms of a disease diminish or disappear. In people infected with HIV, effective treatment regimens may result in the remission of HIV-associated symptoms and conditions.
• Renal
• Pertaining to the kidneys.
• Rescue Therapy
• See: Salvage Therapy.
• Resistance
• See: Drug Resistance.
• Resistance Testing
• A laboratory test to determine if an individual's HIV strain is resistant to any anti-HIV drugs. See also: Genotypic Assay, Phenotypic Assay, Drug Resistance.
• Retinal Detachment
• Separation of the retina from the inner wall of the eye. Retinal detachment can be a complication of cytomegalovirus (CMV) retinitis and can cause vision loss. See also: Cytomegalovirus Retinitis.
• Retinitis
• Inflammation of the retina, the thin layer of tissue that lines the inside back wall of the eye and functions like the film of a camera. In people with HIV, retinitis can be caused by cytomegalovirus (CMV). If untreated, retinitis can lead to blindness. Symptoms include floating spots, flashing lights, blind spots, and blurred vision. See also: Cytomegalovirus, Cytomegalovirus Retinitis.
• Retrovirus
• A type of virus that stores its genetic information in a single-stranded RNA molecule, then constructs a double-stranded DNA version of its genes using a special enzyme called reverse transcriptase. The DNA copy is then integrated into the host cell's own genetic material. HIV is an example of a retrovirus. See also: Reverse Transcriptase, Integration, Provirus.
• Reverse Transcriptase (RT)
• An enzyme found in HIV and other retroviruses. RT converts single-stranded HIV RNA into double-stranded HIV DNA. Some anti-HIV drugs interfere with this stage of HIV's life cycle. See also: Nucleoside Reverse Transcriptase Inhibitors, Non-Nucleoside Reverse Transcriptase Inhibitors, Provirus, Retrovirus.
• Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR)
• A laboratory test that measures the amount of HIV RNA (also known as viral load) in a blood sample by replicating HIV's genetic material to measurable levels. RT-PCR is the primary way that health care providers monitor HIV infection and its treatment. See also: Polymerase Chain Reaction, Viral Load.
• Ribonucleic Acid (RNA)
• Chemical structure that carries genetic instructions for protein synthesis. Although DNA is the primary genetic material of cells, RNA is the genetic material for some viruses. See also: Deoxyribonucleic Acid, Messenger RNA.
• RNA
• See: Ribonucleic Acid.
• RT
• See: Reverse Transcriptase.
• RT-PCR
• See: Reverse Transcriptase-Polymerase Chain Reaction.
• Ryan White Care Act
• The Ryan White Comprehensive AIDS Resources Emergency (CARE) Act is Federal legislation that addresses unmet health needs of people living with HIV/AIDS by funding primary health care and support services that enhance access to and retention in care. The CARE Act is administered by the Health Resources and Services Administration (HRSA). See also: Health Resources and Services Administration.