HIV

B lymphocytes (B cells)

One of the two major classes of lymphocytes (white blood cells); they are involved in the production of antibodies.

Bacteriostatic

Capable of slowing the growth of bacteria.

Bactrim

Brand name of trimethoprim/sulfamethoxazole (another brand name is Septra).

See Trimethoprim/sulfamethoxazole; Cotrimoxazole; Septra.

B-cell lymphoma

See Lymphoma.

B-cells

See B lymphocytes (B cells).

BCG

Bacille Calmette-Guerin — a TB vaccine.

bDNA test

See Branched DNA assay.

BID

Twice each day.

Biopsy

Surgical removal of a piece of tissue from a person for microscopic examination to make a diagnosis (eg, to determine whether abnormal cells such as cancer cells are present).

Bisexual

Having sexual relations with both females and males.

BIW

Twice each week.

Blinded study

A clinical research study in which participants are unaware as to whether they are receiving the experimental drug or a placebo (or another drug).

See Double-blind study.

BMI

Body mass index (kilogram/meter²).

Body fluids

Any fluid in the human body, such as blood, urine, saliva (spit), sputum, tears, semen, mother's milk, or vaginal secretions. Only blood, semen, mother's milk, and vaginal secretions have been linked directly to the transmission of HIV.

Body surface area (BSA)

A measure of the overall surface of a person calculated from height and weight. Body surface area is expressed in meters squared (m²).

Booster

A second or subsequent dose of a vaccine given to increase the immune response to the original dose.

Branched DNA assay

(bDNA test) A test developed by Bayer for measuring the amount of HIV (as well as other viruses) in blood plasma. Test results are calibrated in numbers of virus particle equivalents per milliliter of plasma.

Breakthrough infection

An infection caused by the infectious agent the substance is designed to protect against. As it pertains to a vaccine trial, the infection may be caused by exposure to the infectious agent, such as HIV, before the vaccine has taken effect, before all doses of the vaccine have been given, or as a result of the vaccine not being effective.

Bronchoscopy

Examination of the bronchial (lung) passages through the tube of an endoscope (usually a curved flexible tube containing fibers that carry light down the tube and project an enlarged image up the tube to the viewer) that is inserted into the upper lungs.

Burkitt lymphoma

A B-cell-type lymphoma.