A (11) | B (2) | C (16) | D (9) | E (5) | F (2) | G (7) | H (10) | I (7) | L (1) | M (3) | N (7) | P (19) | Q (2) | R (12) | S (10) | T (1) | V (4)

The process of assigning trial participants to either a treatment group where they receive the drug product, or a control group where they receive the placebo. A methodology is employed that applies an element of chance to determine the assignments. This method reduces bias.

randomized trial

A study in which the participants are assigned by chance to separate groups that compare different treatments. Neither the researchers nor the participants can choose group assignments. Using chance to assign people to groups means the treatments they receive can be compared objectively.


A molecule on the surface of a cell that serves as a recognition or binding site for antigens, antibodies, hormones or other cellular or immunologic components. When chemical messengers bind to receptors, various cellular functions are activated or inhibited. Viruses enter host cells by interacting with receptors on the cell surface, and many drugs exert their effects by binding to receptors, thereby altering cellular function.

regulatory body

The group or groups responsible for making sure that all laws regulating research, testing, and other stages of drug development and approval are upheld during clinical trials and research and development for a new product. Regulators also establish what will be required for each new product to be approved for use. The Food and Drug Administration (FDA) is the key regulatory body for new drug products in the United States.

replication stage

The stage in the HIV life cycle when the genetic material of the virus is copied using the reverse transcriptase enzyme. This stage occurs after fusion. Once the virus has permanently integrated into the host cell, the virus can then duplicated using the cell’s own biological processes.


Some microorganisms, including viruses like HIV, adapt so they can survive and multiply in the presence of drugs that would normally weaken or kill them. A drug-resistant HIV strain can multiply in the presence of one or more ARV drugs because of its genetic make-up.


HIV and other viruses that carry their genetic material in the form of single-stranded RNA rather than the double-stranded DNA .  Retroviruses also have the enzyme reverse transcriptase that can copy RNA into cDNA, leading to infection of the host cell.

reverse transcriptase

An HIV enzyme used by the virus to copy its RNA into cDNA, to allow for its incorporation into the host cell DNA.

reverse transcriptase inhibitor

A class of microbicides that works by preventing the action of the reverse transcriptase enzyme.

reverse transcription

The process during viral replication when the HIV enzyme reverse transcriptase converts single-stranded viral RNA into double-stranded DNA so that the HIV genetic material can be integrated into the human cell. See also viral replication.

ribonucleic acid

Also called RNA, ribonuclei acid is a type of macromolecule that stores and transfers genetic information. Although DNA is the primary genetic material of mammalian cells, RNA is the genetic material for some viruses, including HIV. 


ribonucleic acid