lymphocyte (B cell):
one of the two major classes of lymphocytes, B lymphocytes
are white blood cells of the immune system that
are derived from the bone marrow and spleen. B cells
develop into plasma cells, which produce antibodies.
an insect virus used in the production of subunit
vaccines. By splicing a specific HIV gene(s) into
the baculovirus genome, and then combining this
construct with insect cells, mass quantities of
the purified HIV protein(s) coded for by these two
HIV gene(s) can be made by the cells for use as
a vaccine. (See also expression system.)
the time point in a study just before initiation
of intervention (vaccination) when starting measurements
are taken. Measurements taken at later time points
may be compared with those taken at baseline to
binding antibody: an antibody that attaches to some part of HIV. Binding antibodies
may or may not lead to the killing of the virus.
blinded study: a clinical trial in which participants are unaware as to whether
or not they are in the experimental or control
arm of the study. (See also double‑blind
a second or later vaccine dose given after the primary
dose(s) to increase the immune response to the original
vaccine antigen(s). The vaccine given as the booster
dose may or may not be the same as the primary vaccine.
(See also prime-boost.)
DNA) assay: laboratory test for measuring the amount of virus in blood plasma.
The test detects an amplified luminescent signal
whose brightness depends on the amount of viral
infection: an infection, which the vaccine is intended to prevent, that occurs
in a volunteer during the course of a vaccine trial.
Such an infection is caused by exposure to the infectious
agent and may occur before or after the vaccine
has taken effect or all doses have been given.
canarypox: a virus that infects birds and is used as a live vector for HIV vaccines.
It can carry a large quantity of foreign genes.
Canarypox virus cannot grow in human cells, an important
safety feature. (See also ALVAC- HIV™; vector.)
abbreviation for “cluster of differentiation,” referring
to cell surface molecules that are used to identify
stages of maturity of immune cells, for example,
CD4+ T cells.
T lymphocyte: immune cell that carries a marker on its surface known as "cluster
of differentiation 4" (CD4). These cells are
the primary targets of HIV. Also known as helper
T cells, CD4+ T cells help orchestrate
the immune response, including antibody responses
as well as killer T cell responses. (See also T
T lymphocyte: immune cell that carries the “cluster of differentiation 8"
(CD8) marker. CD8 T cells may be cytotoxic T lymphocytes
or suppressor T cells. (See also cytotoxic T
lymphocyte (CTL); T cell.)
immunity (cellular immunity):
the immune response coordinated by helper T cells
and CTLs. This branch of the immune system targets
cells infected with microorganisms such as viruses,
fungi and certain bacteria.
in vaccine experiments, the deliberate exposure
of an immunized animal to the infectious agent.
Challenge experiments are never done
in human HIV vaccine research.
hamster ovary) cell: a cell used as a “factory” in genetic engineering to make certain
subunit vaccines. CHO cells are derived from mammals
and are advantageous because they add carbohydrates
(a sugar coat) to the protein, much like naturally
infected human cells do.
also called a subtype. A group of related HIV isolates
classified according to their degree of genetic
similarity (such as of their envelope proteins).
There are currently two groups of HIV‑1 isolates,
M and O. M consists of at least nine clades, A through
I. Group O may consist of a similar number of clades.
(See also isolate.)
groups of individuals who share one or more characteristics
in a research study and who are followed over time.
For example, a vaccine trial might include two cohorts,
a group at low risk for HIV and a group at higher
risk for HIV.
blood proteins that play an important role in the
immune response. Generally, complement proteins
amplify the effects of antibodies and inflammation.
in vaccine clinical trials, the control group is
given either the standard treatment for the disease
or an inactive substance called a placebo. The control
group is compared with one or more groups of volunteers
given experimental vaccines to detect any effects
of the vaccines.
the protein capsule surrounding a virus’ DNA or
RNA. In HIV, p55, the precursor molecule to the
core, is broken down into the smaller molecules
p24, p17, p7 and p6. HIV’s core is primarily composed
immunity (correlates of protection):
the immune responses that must be present to protect
an individual from a certain infection. The precise
correlates of immunity in HIV transmission are unknown.
a soluble, hormone-like protein produced by white
blood cells that acts as a messenger between cells.
Cytokines can stimulate or inhibit the growth and
activity of various immune cells. Cytokines are
essential for a coordinated immune response and
can also be used as immunologic adjuvants. HIV replication
is regulated by a delicate balance among cytokines.
the living matter within a cell (excluding the nucleus)
that is responsible for the function of the cell
(for example, protein synthesis).
lymphocyte (CTL): immune system cell that can destroy cancer cells and cells infected
with viruses, fungi or certain bacteria. CTLs, also
known as killer T cells, carry the CD8 marker. CTLs
kill virus-infected cells, whereas antibodies generally
target free-floating viruses in the blood. CTL responses
are a proposed but unproven correlate of HIV immunity.
(See also CD8+ T lymphocyte.)
elimination of a gene either in nature or in the
dendritic cell: immune cell with threadlike tentacles called dendrites used to enmesh
antigen, which they present to T cells. Langerhans
cells, found in the skin, and follicular dendritic
cells, found in lymphoid tissues, are both types
of dendritic cells. (See also antigen-presenting
acid): the double-stranded, helical molecular chain found within the nucleus
of each cell. DNA carries the genetic information
that encodes proteins and enables cells to reproduce
and perform their functions.
(nucleic acid vaccine): direct injection of a gene(s) coding for a specific antigenic protein(s),
resulting in direct production of such antigen(s)
within the vaccine recipient in order to trigger
an appropriate immune response.
a region of a gene or gene product. A neutralizing
domain is a specific site on the virus to which
a neutralizing antibody is directed.
study: a clinical trial in which two or more doses (starting at a lower
dose and proceeding to higher doses) of a vaccine
are tested against each other to determine which
dose works best and has acceptable side effects.
relationship: the relationship between the dose of a vaccine and an immune or physiologic
response. In vaccine research, a dose‑response
effect means that as the dose of the vaccine increases,
so does the level of the immune response (antibodies
and CTL activity).
study: a clinical trial in which neither the study staff nor the participants
know which participants are receiving the experimental
vaccine and which are receiving a placebo or another
therapy. Double-blind trials are thought to produce
objective results, since the
volunteer’s expectations about the experimental
vaccine do not affect the outcome.
DSMB (Data and
Safety Monitoring Board): a committee of independent clinical research experts who review data
while a clinical trial is in progress. The DSMB
ensures that participants are not exposed to undue
risk and looks for any differences in effectiveness
between the experimental and control groups. The
DSMB may review the data in such a way that they
know which group received the vaccine and which
group did not. This group may also recommend that
a trial be modified or stopped if there are safety
concerns or if the trial objectives have been achieved.
Virus) cell line: a herpesvirus; in vaccine research, used to make target cells for
in vaccine research, the ability of a vaccine to
produce a desired clinical effect, such as protection
against a specific infection, at the optimal dosage
and schedule in a given population. A vaccine may
be tested for efficacy in Phase 3 trials if it appears
to be safe and shows some promise in smaller Phase
1 and 2 trials.
a blood test that detects antibodies based on a
reaction that leads to a detectable color change
in the test tube. The HIV ELISA is commonly used
as the initial screening test because it is relatively
easy and inexpensive to perform. Because the HIV
ELISA is designed for optimal sensitivity -- that
is, it detects all persons with HIV antibodies as
well as some who don’t have them (false positives)
-- a positive HIV ELISA test must be confirmed by
a second, more specific test such as an HIV Western
based on experience or observational information
and not necessarily on proven scientific data. In
the past, vaccine trials have been performed based
exclusively on empirical data and without a full
understanding of the disease processes or correlates
a suspension of droplets of one liquid in another
liquid (such as oil and water). The two liquids
do not actually combine but are instead suspended
within one another.
the results of an intervention such as vaccination
compared among different study groups in a clinical
trial. In early vaccine trials, common endpoints
are safety and specific types and intensities of
immune responses (neutralizing antibodies, CTL responses).
enhancing antibody: a type of binding antibody, detected in the test tube and formed
in response to HIV infection, that may enhance the
ability of HIV to produce disease. Theoretically,
enhancing antibodies could attach to HIV virions
and enable macrophages to engulf the viruses. However,
instead of being destroyed, the engulfed virus may
remain alive within the macrophage, which then can
carry the virus to other parts of the body. It
is currently unknown whether enhancing antibodies
have any effect on the course of HIV infection.
Enhancing antibodies can be thought of as the opposite
of neutralizing antibodies.
a protein produced by cells to accelerate a specific
chemical reaction without itself being altered.
Enzymes are generally named by adding the ending
“-ase” to the name of the substance on which the
enzyme acts (for example, protease is an enzyme
that acts on proteins).
a gene of HIV that codes for gp160, the precursor
molecule that breaks down into the envelope proteins
gp120 and gp41. (See also gp.)
outer surface of a virus, also called the coat.
Not all viruses have an envelope. (See also virus;
the study of the frequency and distribution of disease
in human populations.
a specific site on an antigen that stimulates specific
immune responses, such as the production of antibodies
or activation of immune cells.
expression system: in genetic engineering, the cells into which a gene has been inserted
to manufacture desired proteins. Chinese hamster
ovary (CHO) cells and baculovirus/insect cells are
two expression systems that are used to make recombinant
functional antibody: an antibody that binds to an antigen and has an effect that can be
demonstrated in laboratory tests. For example, neutralizing
antibodies are functional antibodies that inactivate
HIV or prevent it from infecting other cells.
a gene of HIV that codes for p55, the core protein.
p55 is the precursor of HIV proteins p17, p24, p7
and p6 that form HIV’s capsid or core, the inner
protein shell surrounding HIV’s strands of RNA.
genetic engineering: the laboratory technique of recombining genes to produce proteins
used for drugs and vaccines.
the complete set of genes present in a cell or virus.
abbreviation for glycoprotein. A protein molecule
that is glycosylated, that is, coated with a carbohydrate,
or sugar. The outer coat proteins of HIV are glycoproteins.
The number after the gp (e.g., gp160, gp120, gp41)
is the molecular weight of the glycoprotein.
glycoprotein 41. A protein imbedded in the outer
envelope of HIV that anchors gp120. gp41 plays a
key role in HIV's infection of CD4+ T
cells by facilitating the fusion of the viral and
cell membranes. Antibodies to gp41 can be detected
on a screening HIV ELISA.
glycoprotein 120. One of the proteins that forms
the envelope of HIV. gp120 projects from the surface
of HIV and binds to the CD4 molecule on helper T
cells. gp120 has been a logical experimental HIV
vaccine because the outer envelope is the first
part of the virus that encounters antibody.
glycoprotein 160, a precursor of HIV envelope proteins
gp41 and gp 120.
half‑life: the time required for half the amount of a substance to be eliminated
from the body or to be converted to another substance(s).
helper T cell: lymphocyte bearing the CD4 marker. Helper
T cells are the chief regulatory cells of the immune
response. They are responsible for many immune system
functions, including turning antibody production
on and off, and are the main target of HIV infection.
(See also CD4+ T lymphocyte.)
similar in appearance, structure and usually function.
For HIV, the same strain of the virus.
a plant or animal harboring another organism.
HLA (human leukocyte
antigen): two major classes of molecules on cell surfaces.
HLA class I:
molecules that exist on all nucleated cells and
identify the cell as “self.” In addition, if the
cell is infected by a virus or other microbe, the
cell displays the invader’s antigens in combination
with the cell’s HLA class I molecules. The presence
of the foreign peptide antigen with the HLA class
I molecule activates CD8+ CTLs specific
for that antigen.
HLA class II:
molecules that are found on antigen-presenting cells
such as macrophages. These cells process soluble
antigens such as toxins or other proteins made by
microbes and then display them on their surface
as peptide antigens in combination with HLA Class
II molecules. Helper T cells specific for these
antigens are then able to be activated and respond
to the presence of the invading microbe.
humoral immunity: see antibody-mediated immunity.
a tentative statement or supposition, which may
then be tested through research.
immune complex: the result of a reaction between an antigen and a specific antibody.
This combination of antigen bound by antibody may
or may not cause adverse effects in a person.
immune deficiency: a breakdown or inability of certain parts of the immune system to
function, thus making a person susceptible to diseases
that they would not ordinarily develop.
natural or acquired resistance provided by the immune
system to a specific disease. Immunity may be partial
or complete, specific or nonspecific, long‑lasting
the process of inducing immunity by administering
an antigen (vaccine) to allow the immune system
to prevent infection or illness when it subsequently
encounters the infectious agent.
a substance capable of provoking an immune response.
Also called an antigen.
immunocompetent: capable of developing an immune response; possessing a normal immune
immunogenicity: the ability of an antigen or vaccine to stimulate immune responses.
immunoglobulin: a general term for antibodies, which bind to invading organisms,
leading to their destruction. There are five classes
of immunoglobulins: IgA, IgG, IgM, IgD and IgE.
(See also antibody.)
immunotherapy: a treatment that stimulates or modifies the body's immune response.
the rate of occurrence of some event, such as the
number of individuals who get a disease divided
by a total given population per unit of time. (Contrast
criteria: the medical or social reasons why a person may or may not qualify
for participation in a clinical trial. For example,
some trials may exclude people with chronic liver
disease or with certain drug allergies; others may
include only people with a low CD4+ T-cell count.
new drug): the status
of an experimental drug after the FDA agrees that
it can be tested in people.
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.
a vaccine (or drug or behavioral therapy) used in
a clinical trial to improve health or alter the
course of disease.
an artificial environment created outside a living
organism (e.g., in a test tube or culture plate)
used in experimental research to study a disease
or biologic process.
testing within a living organism, e.g., human or
Review Board): a committee
of physicians, statisticians, community advocates
and others that reviews clinical trial protocols
before they can be initiated. IRBs ensure that the
trial is ethical and that the rights of participants
are adequately protected.
a particular strain of HIV-1 taken from a person.
an HIV-1 isolate used in HIV vaccine development.
LAI is also referred to as IIIB or LAV. LAI belongs
to clade B, the clade to which most HIV-1 found
in America and Europe belongs. (See also clade.)
vaccine: a vaccine that uses a non-disease-causing organism (virus or bacterium)
to transport HIV or other foreign genes into the
body, thereby stimulating an effective immune response
to the foreign products. This type of vaccine is
important because it is particularly capable of
inducing CTL activity. Examples of organisms used
as live vectors in HIV vaccines are canarypox and
a type of white blood cell produced in the lymphoid
organs that is primarily responsible for immune
responses. Present in the blood, lymph and lymphoid
tissues. (See also B cell and T cell.)
lymphoid tissue: tonsils, adenoids, lymph nodes, spleen and other tissues that act
as the body's filtering system, trapping invading
microorganisms and presenting them to squadrons
of immune cells that congregate there.
a large immune system cell in the tissues that devours
invading pathogens and other intruders. Macrophages
stimulate other immune cells by presenting them
with small pieces of the invaders. Macrophages also
can harbor large quantities of HIV without being
killed, acting as reservoirs of the virus.
the arithmetic average, or the sum of all the values
divided by the number of values.
the midpoint value obtained by ranking all values
from highest to lowest and choosing the value in
the middle. The median divides a population into
two equal halves.
memory cells are a subset of T cells and B cells
that have been exposed to specific antigens and
can then proliferate (recognize the antigen and
divide) more readily when the immune system re-encounters
the same antigens. (See also anamestic response.)
MHC (major histocompatibility
complex): the gene cluster that controls certain aspects of the immune response.
Among the products of these genes are the histocompatibility
antigens, such as HLA class I antigens, which are
present on every cell with a nucleus and serve as
markers to distinguish self from non-self. (See
microencapsulated: surrounded by a thin layer of biodegradable substance referred to
as a microsphere. A means of protecting a drug or
vaccine antigen from rapid breakdown. Microencapsulation
may also enhance an antigen’s absorption and the
immune response to that antigen.
an HIV‑1 strain belonging to clade B, the
clade to which most HIV‑1 found in North America
and Europe belong. MN is used in vaccine development.
(See also clade.)
monoclonal antibody: custom‑made, identical antibody that recognizes only one epitope.
a large white blood cell in the blood that ingests
microbes or other cells and foreign particles. When
a monocyte passes out of the bloodstream and enters
tissues, it develops into a macrophage.
monovalent vaccine: a vaccine that contains only one antigen.
mucosal immunity: resistance to infection across the mucous membranes. Mucosal immunity
depends on immune cells and antibodies present in
the linings of reproductive tract, gastrointestinal
tract and other moist surfaces of the body exposed
to the outside world.
a gene of SIV and HIV that regulates the production
of the virus. Vaccines made of SIV virions from
which nef has been removed (nef‑deleted)
have shown promise in monkeys.
antibody: an antibody that keeps a virus from infecting a cell, usually by
blocking receptors on the cells or the virus.
domain: a section of HIV (most commonly on the envelope protein gp120) that
elicits antibodies with neutralizing activity. (See
also V3 loop.)
NK cell (natural
killer cell): a non-specific lymphocyte. NK cells, like killer T cells, attack
and kill cancer cells and cells infected by microorganisms.
NK cells are “natural” killers because they do not
need to recognize a specific antigen in order to
attack and kill.
the central controlling body within a living cell,
usually a spherical unit enclosed in a membrane
and containing genetic codes for maintaining life
systems of the organism and for issuing commands
for growth and reproduction.
trial: a clinical trial in which doctors and participants know which vaccine
is being administered to all participants.
infection: an illness caused by an organism that usually does not cause disease
in a person with a normal immune system. People
with advanced HIV infection suffer opportunistic
infections of the lungs, brain, eyes and other organs.
a protein in HIV's inner core. The p24 antigen test
looks for the presence of this protein in a person's
administered intravenously or by injection. For
example, medications or vaccines may be administered
by injection into the fatty layer immediately below
the skin (subcutaneous), or into the muscle (intramuscular).
Medications, but not vaccines, can also be
administered into a vein (intravenously).
the origin and development of a disease. More specifically,
it’s the way a microbe (bacteria, virus, etc.) causes
disease in its host.
blood mononuclear cell): cells in the bloodstream that have one round nucleus; e.g., lymphocytes
and monocytes. Usually, the majority of circulating
PBMCs are lymphocytes.
chain reaction): a sensitive laboratory technique used to detect and repeatedly copy
small amounts of RNA or DNA. Some PCR tests can
also quantify the amount of RNA or DNA. PCR is used
to measure viral load in persons infected with HIV.
a short compound formed by linking two or more amino
acids. Proteins are made of multiple peptides.
PHA (phytohemagglutinin): a plant chemical used to stimulate the multiplication (proliferation)
of T lymphocytes in laboratory tests.
Phase 1 vaccine
trial: a closely monitored clinical trial of a vaccine conducted in a small
number of healthy volunteers. A Phase 1 is designed
to determine the vaccine’s safety in humans, its
metabolism and pharmacologic actions, and side effects
associated with increasing doses.
Phase 2 vaccine
trial: controlled clinical study of a vaccine to identify common short-term
side effects and risks associated with the vaccine
and to collect information on its immunogenicity.
Phase 2 trials enroll some volunteers who have the
same characteristics as persons who would be enrolled
in an efficacy (Phase 3) trial of a vaccine. Phase
2 trials enroll up to several hundred participants
and have more than one arm.
Phase 2b vaccine
trial: controlled clinical study, also known as a “proof-of-concept” trial,
provides valuable information on the safety and
potential efficacy of the vaccine. A Phase 2b trial
enrolls fewer volunteers and is less expensive than
Phase III efficacy trials.
Phase 3 vaccine
trial: large controlled study to determine the ability of
a vaccine to produce a desired clinical effect on
the risk of a given infection, disease, or other
clinical condition at an optimally selected dose
and schedule. These trials also gather additional
information about safety needed to evaluate the
overall benefit-risk relationship of the vaccine
and to provide adequate basis for labeling. Phase
3 trials usually include several hundred to several
pharmacokinetics: the processes of absorption, distribution, metabolism and excretion
of a drug or vaccine.
an inactive substance administered to some study
participants while others receive the agent under
evaluation, to provide a basis for comparison of
an extrachromosomal ring of DNA, especially of bacterial
origin, that replicates autonomously.
a gene of HIV that codes for the enzymes protease,
reverse transcriptase and integrase.
an enzyme that creates genetic material, either
RNA or DNA, from building blocks.
polyvalent vaccine: a vaccine that is produced from multiple viral strains, or is made
to induce immune responses against multiple strains.
the number of people in a given population affected
with a particular disease or condition at a given
time. Prevalence can be thought of as a snapshot
of all existing cases at a specified time. (Contrast
vaccine: a vaccine designed to prevent HIV infection.
giving one vaccine dose(s) first to induce certain
immune responses, followed by or together with a
second type of vaccine. The intent of priming is
to induce certain immune responses that will be
enhanced by the booster dose(s).
in HIV vaccine research, administration of one type
of vaccine, such as a live-vector vaccine, followed
by or together with a second type of vaccine, such
as a recombinant subunit vaccine. The intent of
this combination regimen is to induce different
types of immune responses and enhance the overall
immune response, a result that may not occur if
only one type of vaccine were to be given for all
prevention of disease.
protease inhibitor: one of a class of anti-HIV drugs designed to inhibit the enzyme protease
and interfere with virus replication. Protease inhibitors
prevent the cleavage of HIV precursor proteins into
active proteins, a process that normally occurs
when HIV replicates.
the detailed plan for a clinical trial that states
the trial's rationale, purpose, vaccine dosages,
routes of administration, length of study, eligibility
criteria and other aspects of trial design.
a virus‑like particle that resembles a virus
but does not contain its genetic information and
cannot replicate. In some viral diseases pseudovirions
can interfere with infection by the real infectious
randomized trial: a study in which participants are assigned by chance to one of two
or more intervention arms or regimens. Randominization
minimizes the differences among groups by equally
distributing people with particular characteristics
among all the trial arms.
reactogenicity: the capacity of a vaccine to produce adverse reactions.
any chemical used in a laboratory test or experiment.
a molecule on the surface of a cell that serves
as a recognition or binding site for antigens, antibodies
or other cellular or immunologic components.
DNA technology: the technique by which genetic material from one organism is inserted
into a foreign cell in order to mass produce the
protein encoded by the inserted genes.
regulatory gene: HIV genes (nef, rev, tat, vpr) that regulate viral replication
in infected cells.
HIV and other viruses that carry their genetic material
in the form of RNA rather than DNA and have the
enzyme reverse transcriptase that can transcribe
it into DNA. In most animals and plants, DNA is
usually made into RNA, hence “retro” is used to
indicate the opposite direction.
HIV and other viruses that carry their genetic material
in the form of RNA rather than DNA and have the
enzyme reverse transcriptase that can transcribe
it into DNA. In most animals and plants, DNA is
usually made into RNA, hence “retro” is used to
indicate the opposite direction.
reverse transcriptase: the enzyme produced by HIV and other retroviruses that enables them
to direct a cell to synthesize DNA from their viral
acid): a single-stranded molecule composed of chemical building blocks,
similar to DNA. The RNA segments in cells represent
copies of portions of the DNA sequences in the nucleus.
RNA is the sole genetic material of retroviruses.
seroconversion: the development of antibodies to a particular antigen. When people
develop antibodies to HIV or an experimental HIV
vaccine, they “seroconvert” from antibody‑negative
to antibody‑positive. Vaccine-induced seroconversion
does not represent an infection. Instead, vaccine-induced
seroconversion is an expected response to vaccination
that may disappear over time.
positive or negative results of a diagnostic test,
such as an ELISA, for a specific antibody.
an HIV‑1 strain used in vaccine development.
SF‑2 belongs to clade B, the clade to which
most HIV‑1 strains found in North America
and Europe belong. (See also clade.)
genetically engineered hybrid virus having an HIV
envelope and an SIV core.
(See adverse reaction.)
immunodeficiency virus): an HIV‑like virus that infects and causes an AIDS‑like
disease in some species of monkeys.
significance: the probability that an event or difference occurred as the result
of the intervention (vaccine) rather than by chance
alone. This probability is determined by using statistical
tests to evaluate collected data. Guidelines for
defining significance are chosen before data collection
immunity: an immune response that completely prevents the establishment of
one type of HIV. HIV is so heterogeneous, no two
isolates are exactly the same. When HIV is isolated
from an individual, and worked on in the lab, it
is given its own unique identifier, or strain name
(i.e., MN, LAI).
stratification: separation of a study cohort into subgroups or strata according to
also called a clade. With respect to HIV isolates,
a classification scheme based on genetic differences.
subunit vaccine: a vaccine that contains only part of the virus or other microorganism.
HIV subunit vaccines produced by genetic engineering
are referred to as recombinant subunit HIV vaccines.
surrogate marker: an indirect measure of disease progression. In HIV disease, the number
of CD4+ T cells per cubic millimeter
of blood is often used as a surrogate marker.
giant cells formed by the fusion of an HIV‑infected
blood cell with one or more uninfected ones.
white blood cell critical to the immune response.
Among these are CD4+ T cells and CD8+
T cells. The “T” stands for the thymus, where T
lymphocytes mature. (See also lymphocyte.)
proliferation assay: a test used to measure the memory of T cells to antigens or microbes,
such as HIV.
HIV vaccine: a vaccine designed to boost the immune response to HIV in a person
already infected with the virus. Also referred to
as an immunotherapeutic vaccine.
a section of the HIV gp120 surface protein that
appears to be important in stimulating neutralizing
antibodies. (See also neutralizing domain.)
a preparation that stimulates an immune response
that can prevent an infection or create resistance
to an infection.
a cowpox virus, formerly used in human smallpox
vaccines. Employed as a vector in HIV vaccines to
transport HIV genes into the body.
in vaccine research, a bacterium or virus that does
not cause disease in humans and is used in genetically
engineered vaccines to transport genes coding for
antigens into the body to induce an immune response.
(See also vaccinia and canarypox.)
the presence of virus in the bloodstream.
a mature infectious virus particle existing outside
a microorganism composed of a piece of genetic material
-- RNA or DNA -- surrounded by a protein coat. To
replicate, a virus must infect a cell and direct
its cellular machinery to produce new viruses.
a blood test to detect antibodies to several specific
components of a virus such as HIV. This test is
most often used to confirm a positive ELISA.