Vaccine Science:

• Overview
• Polio Vaccines
• Hookworm Vaccine
• Vaccine Safety
• Glossary

Glossary

A   |   B-D   |   E-G   |   H-K   |   L-N   |   O-P   |   Q-S   |   T-Z

H

Haemophilus influenza type b (Hib): A bacterial infection that may result in severe respiratory infections, including pneumonia, and other diseases such as meningitis.

Hemoglobin: The oxygen-carrying part of the red blood cell.

Hemolysin: 1. A substance liberated by a living agent and capable of causing lysis of red blood cells and liberation of their hemoglobin 2. A sensitizing antibody that combines with red blood cells of the antigenic type that stimulated formation of the h., affecting the cells in such a manner that complement fixes with the antibody-cell union and causes dissolution of the cells, with liberation of their hemoglobin.

Hepatitis B: Hepatitis caused by a virus and transmitted by exposure to blood or blood products or during sexual intercourse. It causes acute and chronic hepatitis. Chronic hepatitis B can cause liver disease, cirrhosis, and liver cancer.

Hepatocyte: Liver cell.

Herd immunity: See community immunity .

Herpes Zoster: A disease characterized by painful skin lesions that occur mainly on the trunk (back and stomach) of the body but which can also develop on the face and in the mouth. Complications include headache, vomiting, fever and meningitis. Recovery may take up to 5 weeks. Herpes Zoster is caused by the same virus that is responsible for chickenpox. Most people are exposed to this virus during childhood. After the primary infection (chickenpox), the virus becomes dormant, or inactivated. In some people the virus reactivates years, or even decades, later and causes herpes zoster. Also known as the shingles.

Histocompatibility: Literally means the ability of cells to get along with each other. Used to determine whether a transplanted tissue or organ will be acceptable by the recipient. Histocompatibility is determined by the major histocompatibility complex molecules.

HIV: Human immunodeficiency virus, the causative agent of acquired immunodeficiency syndrome (AIDS). A retrovirus of the lentivirus family that selectively infects CD4 T cells leading to their depletion, which eventually results in immunodeficiency.

HIV gag: A structural component of the HIV genome coding for various structures on the surface of the virus functionally necessary for attachment of the virus to a susceptible cell, such as p24, p17. Other examples of the genome include env (envelope genes) and pol (polymerase enzymes).

HLA: The acronym for Human Leukocyte Antigen is the genetic designation for the human MHC. Individual loci are designated by upper case letters, as in HLA-A and alleles are designated in numbers, as in HLA-A 201.

Hodgkins disease: A malignant disease on which antigen presenting cells resembling dendritic cells seem to be the transformed cell type.

Hodgkins lymphoma: A form of Hodgkins disease in which lymphocytes predominate, and it has a much better prognosis than the nodular sclerosis form of this disease in which the predominant cell type is non-lymphoid.

Host: A plant or animal harboring another organism.

HPV: Human papilloma virus the causative agent of genital warts (condylomata acuminata) a sexually transmitted infection.

HPV-16: Serotypes 16 and 18 commonly associated with progression to cancer of the cervix in women.

Humoral immunity: Antibody-mediated immunity made in a humoral immune response. Humoral immunity can be transferred to unimmunized recipients by using immune serum containing specific antibody.

Hypersensitivity: A condition in which the body has an exaggerated response to a substance (e.g. food or drug). Also known as an allergy.

Hyposensitivity: A condition in which the body has a weakened or delayed reaction to a substance.

Hypnozoite: A form of the malaria parasite that remains inactive within the liver and can produce relapses.

I

I.D.: Intradermal, a mode of delivery of therapy.

I.M.: Intramuscular, within the substance of muscles, a mode of delivery for therapeutic agents.

I.P.: Intraperitoneal, within the peritoneal cavity.

I.V.: Intravenous, within the venous system.

ICAM: Intercellular adhesion molecule. ICAM-1, ICAM-2, and ICAM-3 are cell surface ligands for the leukocyte integrins and are crucial in the binding of lymphocytes and other leukocytes to certain cells, including antigen-presenting cells and endothelial cells. They are members of the immunoglobulin superfamily.

IFN: Interferon.

Ig: Immunoglobulin.

IL: Interleukin, a type of cytokine produced by leukocytes that influences a variety of cells.

Immune complex: The result of the malaria parasite that remains inactive within the liver and can produce relapses.

Immune globulin: A protein found in the blood that fights infection. Also known as gamma globulin.

Immune response: The reaction of the immune system to foreign substances.

Immune system: The complex system in the body responsible for fighting disease. Its primary function is to identify foreign substances in the body (bacteria, viruses, fungi or parasites) and develop a defense against them. This defense is known as the immune response. It involves production of protein molecules called antibodies to eliminate foreign organisms that invade the body.

Immunity: Protection against a disease. There are two types of immunity, passive and active. Immunity is indicated by the presence of antibodies in the blood and can usually be determined with a laboratory test. See active and passive immunity.

Immunization: The process or procedure by which a subject (person, animal, or plant) is rendered immune, or resistant to a specific disease. This term is often used interchangeably with vaccination or inoculation, although the act of inoculation does not always result in immunity.

Immunogen: A substance capable of provoking an immune response. Also called an antigen.

Immunogenicity: The ability of an antigen or vaccine to stimulate immune responses.

Immunoglobulin: A synonym for antibody.

Immunosuppression: When the immune system is unable to protect the body from disease. This condition can be caused by disease (like HIV infection or cancer) or by certain drugs (like those used in chemotherapy). Individuals whose immune systems are compromised should not receive live, attenuated vaccines.

In-: In, within, inside.

In vitro: In an artificial environment, referring to test or process conducted, for example, in a test tube or culture medium. Cf. in vivo. [L. in glass].

In vivo: In a living body or organism, referring to a test or process in a living organism. Cf. in vitro. [L. in the living body].

Inactive vaccine: A vaccine made from viruses and bacteria that have been killed through physical or chemical processes. These killed organisms cannot cause disease.

Inapparent infection: The presence of infection without symptoms. Also known as subclinical or asymptomatic infection.

Incidence: The number of new disease cases reported in a population over a certain period of time.

Incubation period: The time from contact with infectious agents (bacteria or viruses) to onset of disease.

IND: investigational new drug.

Inducible NO synthase or iNOS: macrophages and other cells have an iNOS, which is induced by many different stimuli to activate NO synthesis. This is a major mechanism of host resistance to intracellular infection in mice, and probably in humans as well.

Infection: An invasion of an organism by a pathogen such as bacteria or viruses. Some infections lead to disease.

Infection Control: The activities aiming at the prevention and the spread of pathogens between patients, from healthcare workers to patients, and from patients to healthcare workers in the healthcare setting.

Infectious: Capable of spreading disease. Also known as communicable.

Infectious agents: Organisms capable of spreading disease (e.g. bacteria or viruses).

Inflammation: Redness, swelling, heat and pain resulting from injury to tissue (parts of the body underneath the skin). Also known as swelling.

Inflammatory Bowel Disease (IBD): A general term for any disease characterized by inflammation of the bowel. Examples include colitis and Crohn's disease. Symptoms include abdominal pain, diarrhea, fever, loss of appetite and weight loss.

Informed consent: An agreement signed by prospective volunteers for a clinical research trial that indicates their understanding of (1) why the research is being done, (2) what researchers want to accomplish, (3) what will be done during the trial and for how long, (4) what risks are involved, (5) what, if any, benefits can be expected from the trial, (6) what other interventions are available, and (7) the participant's right to leave the trial at any time.

Injection: The administration of a substance into the skin, subcutaneous tissue, muscle tissue, or veins.

Innate immunity: components of the immune system that everyone is born with.

Interferon (IFN): A class of small glycoproteins that exert antiviral activity at least in homologous cells through cellular metabolic processes involving synthesis of double stranded RNA, which is an intermediate in replication of RNA viruses. IFNs are classified in three groups, alpha, beta, and gamma, based on their reactivities with antibodies as well as their physico-chemical properties and their cells of origin and method of induction.

Intra-: Inside, within; opposite of extra-.

Intracellular vaccines: vaccines within a cell or cells.

Intramuscular injection: An injection made into the body of a muscle.

Investigational new drug (IND): The pre-approval status of an experimental drug or biologic (e.g. vaccine) after the U.S. Food and Drug Administration (FDA) agrees that it can be tested in people (generally done in order to collect sufficient data for licensure). "IND" often refers to the application to obtain this pre-approval status.

Investigational vaccine: A vaccine that has been approved by the Food and Drug Administration (FDA) for use in clinical trials on humans. However, investigational vaccines are still in the testing and evaluation phase and are not licensed for use in the general public.

IRB (Institutional Review Board): A committee of physicians, statisticians, community advocates and other that reviews clinical trial protocols before they can be initiated and is responsible for monitoring the safety of clinical trials at that institution. IRBs ensure that the trial is ethical and that the rights of participants are adequately protected.

IR genes: Immune response genes are genetic polymorphisms that control the intensity of the immune response to a particular antigen. Virtually all Ir phenotypes are due to the differential binding of peptide fragments of antigen to MHC molecules, especially MHC class II molecules. The term is little used now. An immune response gene defect is usually, but not always due to failure to bind an immunogenic peptide, so that no T cell response is observed.

J

Jaundice: Yellowing of the eyes. This condition is often a symptom of hepatitis infection.

Jet injector: Needleless device that allows the injection of a substance under pressure through the skin without a needle.

K

Killer T cell: another term used for cytotoxic T cells.

Ky1 adjuvant: A form of adjuvant.

A   |   B-D   |   E-G   |   H-K   |   L-N   |   O-P   |   Q-S   |   T-Z