A breakdown or inability of certain parts of the immune system to function, thus making a person susceptible to certain diseases that they would not ordinarily develop.

The activity of the immune system against foreign substances.

The body's complicated natural defence against disruption caused by invading foreign agents (e.g., microbes, viruses). There are two aspects of the immune system's response to disease: innate and acquired. The innate part of the response is mobilized very quickly in response to infection and does not depend on recognizing specific proteins or antigens foreign to an individual's normal tissue. It includes complements, macrophages, dendritic cells, and granulocytes. The acquired, or learned, immune response arises when dendritic cells and macrophages present pieces of antigen to lymphocytes, which are genetically programmed to recognize very specific amino acid sequences. The ultimate result is the creation of cloned populations of antibody-producing B cells and cytotoxic T lymphocytes primed to respond to a unique pathogen.

To protect against an infectious disease by vaccination, usually with a weakened (attenuated) or killed form of the disease-causing microorganism. While people are usually immunized against an infectious disease by getting vaccinated, having a disease such as measles, mumps, or rubella one time usually prevents or "immunizes" a person from getting this disease again.

A natural or acquired resistance to a specific disease. Immunity may be partial or complete, long lasting, or temporary.

Refers to an immune system in which the ability to resist or fight off infections and tumours is subnormal.

The ability of an antigen or vaccine to stimulate an immune response.

Also called immune serum globulin. A class of proteins also known as antibodies made by the B cells of the immune system in response to a specific antigen. There are five classes of immunoglobulins IgA, IgD, IgE, IgG, and IgM.

Any substance that influences the immune system.

Any agent or substance that triggers or enhances the body's defence; also called immunopotentiator.

A state of the body in which the immune system is damaged and does not perform its normal functions. Immunosuppression may be induced by drugs (e.g., in chemotherapy) or result from certain disease processes, such as HIV infection.

Treatment aimed at reconstituting an impaired immune system.

A plant or animal toxin (i.e., poison) that is attached to a monoclonal antibody and used to destroy a specific target cell.

("In glass.") An artificial environment created outside a living organism (e.g., a test tube or culture plate) used in experimental research to study a disease or process.

("In life.") Studies conducted within living organisms (e.g., animal or human studies). Culture plate) used in experimental research to study a disease or process.

The number of new cases (e.g., of a disease) occurring in a given population over a certain period of time. The HIV incidence rate in year t would be calculated as the number of new HIV infections in year t, divided by the number of individuals uninfected with HIV at the start of year t.

The time interval between the initial infection with a pathogen (e.g., HIV) and the appearance of the first symptom or sign of disease.

Invasion and replication in the body of organisms, such as viruses, bacteria, fungi. In HIV, infection typically begins when HIV encounters a CD4+ cell. The HIV surface protein gp120 binds tightly to the CD4 molecule on the cell's surface. The membranes of the virus and the cell fuse, a process governed by gp41, another surface protein. The viral core, containing HIV's RNA, proteins, and enzymes, is released into the cell.

An infection capable of being transmitted by direct or intimate contact (e.g., sex).

Campaigns to increase awareness of the modes of HIV transmission, the consequences of HIV infection, and the methods individuals can employ to reduce their risk of infection.

The permission granted by a participant in a research study (including medical research) after receiving comprehensive information about the study. This is a statement of trust between the institution performing the research procedure and the person (e.g., a patient) on whom the research procedures are to be performed. This includes, for example, the type of protection available to people considering entering a drug trial. Before entering the trial, participants must sign a consent form that contains an explanation of:
a. why the research is being done,
b. what the researchers want to accomplish,
c. what will be done during the trial and for how long,
d. what the risks associated with the trial are,
e. what benefits can be expected from the trial,
f. what other treatments are available, and
g. the participant's right to leave the trial at any time. Informed consent also pertains to situations where certain tests need to be performed.

The process of administering therapeutic fluid, other than blood, to an individual by slowly injecting a dilute solution of the compound into a vein. Infusions are often used when the digestive system does not absorb appreciable quantities of a drug or when the drug is too toxic or the volume is too large to be given by quick injection.

The introduction of a substance (inoculum; e.g., a vaccine, serum, or virus) into the body to produce or to increase immunity to the disease or condition associated with the substance.

One of a large group of glycoproteins that act as cytokines. The interleukins are secreted by and affect many different cells in the immune system.

Relating to or situated in the small, narrow spaces between tissues or parts of an organ.

A contraceptive method used to prevent pregnancy. (Also known as the loop).

Injected directly into a muscle.

Time during labour and delivery.

Of or pertaining to the inside of a vein, as of a thrombus. An injection made directly into a vein.

The status of an experimental drug after the FDA agrees that it can be tested in humans.

An individual (as a spore or a single organism), viable part of an organism (as a cell), or a strain that has been separated (as from diseased tissue, contaminated water, or the air) from the whole. Also, a pure culture produced from such an isolate. A particular strain of HIV taken from a patient.