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Glossary of HIV Terminology


















Accelerated Approval: The Food and Drug Administration (FDA) approves medications for their use

in humans in the United States. The AIDS Activist community fought for accelerated approval of HIV

medication through the 80’s and early 90’s because it was essential that we had every option possible

as soon as possible at that time. The purpose of accelerated approval is to speed up the availability of

new drugs for serious, or life-threatening conditions. Accelerated approval of new anti-HIV therapies is

less common today because we are now being much more careful about potential adverse side-effects

and long-term efficacy.

ACTG (AIDS Clinical Trials Group): a network of medical centers around the country in which

federally-funded clinical trials are conducted to test the safety and effectiveness of experimental treatments

for HIV infection and its complications. ACTG studies are sponsored by the National Institute of

Allergy and Infectious Diseases (NIAID), a branch of the National Institutes of Health (NIH). Denver has

an ACTG site at the University of Colorado Health Sciences Center.

Acute: refers to intense, short-term symptoms or illnesses that either resolve or evolve into long-lasting,

chronic disease manifestations.

Acute HIV Infection: also called “Primary Infection,” is the first stage of HIV infection that begins

when the virus enters the body and rapidly begins reproducing copies of itself. Acute infection often

comes with severe flu-like symptoms that occur shortly after HIV infection. Not everyone experiences the

symptoms associated with acute infection, but most do. This initial infection precedes seroconversion

(developing antibodies to HIV) and is characterized by fever, sore throat, headache, skin rash and

swollen glands. New research shows us that if HIV infection is caught during the acute infection stage, it

may be possible to save your immune system’s ability to fight HIV. It is very important to get to an HIV

doctor if you think you have been exposed to HIV or might be experiencing acute infection.

Adherence: Being able to stick to a drug regimen and take it as scheduled every day. See also,


Adverse Event: a toxic reaction to a medical therapy. Some adverse events, or side effects, make

life less enjoyable but do not put your health at risk. Other adverse events can be life-threatening. It is

important to know the possible adverse events associated with medications you are taking so that you

can watch for them.

AIDS (Acquired Immunodeficiency Syndrome): Advanced HIV disease. AIDS is defined by

the Centers for Disease Control (CDC) as a CD4 (helper T-cell) count of less than 200 and/or a CD4%

less than 15 and/or certain opportunistic illnesses common with advanced immune deficiency.

AIDS-Defining Illness: one of the serious illnesses that occurs in HIV-positive individuals and a reason

for an AIDS diagnosis according to the CENTERS FOR DISEASE CONTROL's definition of AIDS.




Alternative/Holistic/Complementary Medicine: Alternative medicine can mean a medical

system that rejects traditional western medicine in favor of an alternative healing system. However, usually

alternative, holistic or complementary medicine refers to the use of multiple forms of healing along

with a western medical approach. For example, using vitamin, mineral and herbal supplementation

along with an HIV regimen. Or, using massage, acupuncture, reiki, etc. to support your well-being, sideeffect

management and immune system. Many “alternative” medical approaches come from other cultures

and have been developed over centuries, such as ayurvedic medicine and acupuncture.

Antibody: a disease-fighting protein created by the immune system, also known as immunoglobulin.

A class of large protein molecules that are produced in response to, and interact with, specific target

molecules known as antigens. HIV is the antigen that stimulates production of HIV antibodies. If a person

tests positive for HIV, they are testing positive for the presence of those antibodies which indicate

HIV infection.

Antigen: a foreign substance, usually a protein that stimulates an immune response.

Assay: a test used to detect the presence and concentration of a drug, virus, or other substance in

bodily fluids or tissues.

Asymptomatic: without signs or symptoms of disease or illness.

Attenuated Virus: a weakened virus strain that can no longer infect or produce disease. An attenuated

virus might potentially be used as a vaccine.


Baseline: the initial time point in a clinical trial or treatment regimen, just before someone starts to

receive the treatment in question. It is important to have baseline blood work drawn before starting

treatment so that you and your health care provider can carefully watch how treatments are working for

you and if you are developing any lab values that can be early warning signs of toxicities. Always get

a baseline CD4 count, viral load and CBC before starting any new meds. These days many providers

also draw baseline liver and lipid panels as well.

BID: Means twice a day. A drug prescribed this way should be taken approximately every 12 hours.

Bioavailability: the extent to which an oral medication is absorbed in the digestive tract and reaches

the bloodstream.

Blood Brain Barrier: the protective barrier that restricts the passage of many substances from the

blood vessels to the tissues of the brain. Not all drugs can cross this barrier.

Bodily Fluids: refers to liquids naturally produced by the body such as urine, saliva and tears. The

only bodily fluids having a high risk for transmission of HIV are: blood, semen, vaginal secretions and

breast milk.


CD4 Cells: also known as T cells, are a type of T-lymphocyte involved in protecting against viral, fungal

and protozoal infections. The CD4 cell directs the immune system’s response to an infection through

a complex series of interactions with antigen presenting cells (macrophages, dendritic cells and B-cells)

and those lymphocytes that directly attack foreign antigens (B-cells, again, and CD8 cells).

CD4 Cell Count: the most commonly used surrogate marker for assessing the state of the immune

system. As CD4 cell count declines, the risk of developing opportunistic infections increases. The normal

range for CD4 cell counts is 500 to 1500 per cubic millimeter of blood. CD4 counts should be checked

every three to six months if CD4 counts are greater than 500/mm3. If the count is lower, testing every

three months is advised.

Centers for Disease Control and Prevention (CDC): the federal public health agency serving

as the center for preventing, tracking controlling and investigating the epidemiology of AIDS and

other diseases.

Chronic: refers to symptoms and diseases that last for an extended period of time without noticeable


Chronic Infection: describes the stage of HIV infection after acute infection, when the virus has

been present in an individual’s body for a period of time. Chronic infection includes asymptomatic, and

symptomatic disease stages.

Clinical: refers to physical signs and symptoms directly observable in the human body.

Clinical Trial: a study done to test an experimental drug in human beings to see if it is safe and

effective. Some clinical trials study long-term effectiveness of combination therapy. Others look at side


Compassionate Use: a process for providing experimental drugs on an individual basis to very

sick patients who have no treatment options. Often, case-by-case approval must be obtained from the

FDA for “compassionate use” of a drug.

Complete Blood Count (CBC): a screening of the most important cellular components of the

blood. A CBC includes the total white blood count, counts of specific types of white blood cells, red

blood cell count, hemoglobin level and platelet count.

Compliance: the degree to which a patient exactly follows a medical plan or particular treatment

regimen. Noncompliance may jeopardize the effectiveness of a drug and lead to resistance. The HIV

activist community has rejected the term compliance because it is a term that implies judgment and

places the blame on patients. Adherence is the preferred term when discussing HIV medication.

Adherence means being able to stick to your regimen.

Contraindication: a condition or circumstance that prevents prescribing a certain treatment to an

individual patient.

Control Arm: the group of participants in a clinical trial who receive standard treatment or a placebo,

against which those receiving the experimental treatment are compared.

CPCRA (Community Programs for Clinical Research on AIDS): a branch of the NIH’s

Division of AIDS that supports clinical trials based on local networks of practicing physicians. These

physicians collect data on their patients who are participating in a treatment trial.

Cross-Resistance: the phenomenon in which a microbe that has acquired resistance to one drug

through direct exposure also turns out to have resistance to one or more other drugs to which it has not

been exposed. Cross-resistance arises because the mechanism of resistance to several drugs is the

same, resulting from identical genetic mutations.


DNA (Deoxyribonucleic Acid): a double-stranded molecule that makes up the chromosomes in

the center of a cell and that carries genetic information in the form of genes.

Disease Progression: Generally, disease progression refers to signs that HIV in a given person is

becoming more threatening to the patient’s general health. It is often characterized by increases in viral

load, decreases in CD4 cell counts, the onset of opportunistic infections, etc. Untreated, HIV eventually

progresses to AIDS.

Double-Blinded: means a clinical trial in which neither the participants nor the researchers know

who is receiving the experimental drug and who is receiving the placebo or standard comparison treatments.

This method is believed to achieve the most accurate clinical trial design because neither the doctors

nor the patients can affect the observed results with their psychological biases. However, doubleblinded

studies often mean extremely high pill counts and regimen scheduling that can lead to clinical

trial results that show less efficacy because so many people drop out of the studies.

Drug Interactions: the effects that occur when two or more drugs are used together. Such effects

may include changes of absorption in the digestive tract, changes in rate of the drugs’ breakdown in

the liver, new or enhanced positive and/or negative side effects and changes in the drugs’ activity.


Efficacy: effectiveness, or how well a drug works. Efficacy should be distinguished from activity,

which is limited to a drug’s immediate effects on the microbe triggering the disease.

ELISA (Enzyme-Linked Immunosorbent Assay): the most common test used to detect the

presence of HIV antibodies in the blood, which indicate HIV infection. A positive ELISA test result must

be confirmed by another test called a Western Blot.

Entry Inhibitor: There are two types of entry inhibitors. A fusion inhibitor blocks the activity of HIV

where the virus sends out a projectile, said to resemble an extremely small harpoon that anchors the

virus to a CD4 T cell. A receptor blocker is conceptually similar to but distinct from, fusion inhibitors.

Receptor blockers work one step before fusion inhibitors. Before a virus can "shoot its harpoon" and

fuse with the cell, it must first find and "dock" with the appropriate cell. This step brings the virus close

enough for the "harpoon" of the fusion step to be fired. It does this by producing proteins that interlock

with other proteins (called receptors) on the cell's surface. The virus will ignore cells that lack the necessary


Epidemiology: the branch of medical science that studies the incidence, distribution and control of

disease in a population.

Expanded Access: refers to any of the FDA procedures (including compassionate use and parallel

track) that distributes experimental drugs to patients who are failing on currently available treatments

and also are unable to participate in ongoing clinical trials.


FDA (Food and Drug Administration): an agency of the United States Department of Health

and Human Services. Aside from regulating the safety of foods and cosmetics, the FDA regulates the

testing of experimental drugs and approves new medical products for marketing based on evidence of

safety and efficacy.

Fusion Inhibitors: a class of anti-HIV drugs designed to prevent HIV from fusing with, and thereby

infecting, CD4 CELLS.


Gene Therapy: any of a number of experimental treatments in which cell genes are altered or

added to. As it concerns HIV, gene therapies attempt to provoke new immune activity, try to render cells

resistant to infection, or provoke the synthesis of enzymes that destroy viral material within cells.

Genotype Testing: a test that can be run on an individuals HIV virus that can show genetic mutations

that have occurred in that individual’s virus, which may lead to drug resistance. Genotype testing

can help your health care provider make informed treatment recommendations that can lead to longer

treatment success.


HAART (Highly Active Antiretroviral Therapy): The combining of HIV medications into

potent anti-HIV regimens with the power to suppress HIV to undetectable levels in an individual’s blood.

HAART Therapy is almost always a combination of 3 or more drugs from two or more classes.

Although, as treatment options continue to grow, how we combine the medications continues to change,

as a rule, 2 HIV medications is not usually considered “highly active,” but rather “sub-optimal” (or not

strong enough).

HIV 1 (human immunodeficiency virus type 1): The virus that causes AIDS. HIV is a retrovirus.

A retrovirus is a virus that infects a cell as RNA and replicates by changing its RNA into DNA

inside of human white blood cells.

HIV 2 (human immunodeficiency virus type 2): a virus closely related to HIV1 that also

leads to immune suppression. HIV 2 idisease progression just longer is epidemic only in West Africa.

Hormone: an active chemical substance formed in one part of the body and carried in the blood to

other parts of the body where it stimulates or suppresses cell and tissue activity.


Immune-Based Therapy: anti-HIV treatment that aims to modulate, supplement or extend the

body’s immune responses against HIV infection or other diseases. Also called immunotherapy.

Immune Deficiency/ Immunosuppression: 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

have contracted with a healthy immune system. Immune deficiencies may be temporary or permanent

and be triggered by genetic mutation, therapy with immune-suppressive drugs (as during organ transplants),

or an infection such as HIV.

Immune Reconstitution: the natural or therapy-induced revival of immune function in a body

damaged by HIV infection, particularly after initiation of a highly active antiretroviral therapy (HAART).

Immune System: the body’s complicated natural defense against disruption caused by invading

microbes and cancers.

Indication: the purpose for which a drug is prescribed. The FDA-approved indications appear on a

printed insert included in the manufacturer’s drug packaging.

Inflammation: the body’s response to tissue injury or infection, mainly localized in the affected tissues

and adjacent blood vessels. Signs of inflammation are redness, swelling, pain and sometimes loss

of function.

Infusion: the process of administering a medication to an individual by slowly injecting a diluted solution

of the compound into a vein. Infusions are often used when the digestive system does not absorb

appreciable quantities of a drug that is also too bulky, or too toxic to be given by quick injection.

Sometimes an infusion may be normal saline solution given because you have become very dehydrated.

Intolerant: unable to take a drug because of an adverse reaction, or side effect.

Intravenous (IV): injected directly into a vein.

In Vitro: refers to laboratory experiments conducted in cell cultures grown in an artificial environment,

for example in a test tube or culture plate.

In Vivo: refers to studies conducted within humans or animals, in a living, natural environment.

-itis: a suffix that indicates inflammation, usually due to infection, of the root word. For example,

vaginitis means inflammation of the vagina.


Jaundice: yellow pigmentation of the skin and whites of the eyes caused by elevated blood levels of

bilirubin. The condition is associated with liver or gallbladder disease, or excessive destruction of red

blood cells.


Killer Cell: a generalized name for immune system cells that kill HIV infected cells. Among the killer

cells are killer T-cells (cytotoxic T-lymphocytes), NK (natural killer) cells and K cells.


Lesion: a disturbed area of tissue; a wound, injury, nodule or tumor on the skin or elsewhere.

Log (Logarithm): formally, the number of times ten must be multiplied with itself to equal a certain

number. For example, 100,000 is log 5 because it is equal to 10 x 10 x 10 x 10 x 10. Logs are used

to measure changes in viral load. For example, a reduction in viral load from 100,000 to 1,000

copies/ml is a two log (or 99 percent) reduction. Note that a half log change is not a five-fold difference

but a change of 3.16-fold (the square root of ten).

Long Term Non-Progressor: an HIV infected person who shows no sign of immune deficiency,

even after many years of infection.

Long Term Survivor: any person with HIV infection that has survived a long time. Anyone living

with HIV for more than 10 years is a long-term survivor and that’s a good thing!

Lipodystrophy: Generally means “a disorder of fat metabolism especially involving loss of fat from

or deposition of fat in tissue” ( In the HIV community Lipodystrophy refers to a set

of symptoms that many people living with HIV who are taking antiretroviral medications experience.

Symptoms include both fat redistribution (thinning arms, legs and face and/or fat accumulation on the

back of the neck, chin, belly and breasts) as well as blood test abnormalities like high cholesterol,

triglycerides or blood sugar levels. The scientific community is still trying to figure out exactly what causes

Lipodystrophy. It appears to be related to antiretroviral medications in addition to age, length of HIV

infection, how well the drugs are working (the better they work, especially for someone who was quite

progressed, the more Lipodystrophy), etc.


Malabsorption: inability of the gastrointestinal tract to absorb fats or other nutrients, drugs or any

ingested substance needed to maintain good health. Malabsorption can lead to wasting syndrome if

not addressed. If you have chronic diarrhea, or are losing weight without trying, talk to your health

care provider so that s/he can run some tests to see if you are absorbing your food and medications.

Malaise: a general feeling of discomfort or uneasiness, often the result of infection or a drug’s side


Malignant: refers to cells or tumors growing in an uncontrolled fashion. Such growths may spread to

and disrupt nearby normal tissue or reach distant sites via the bloodstream. By definition, cancers are

always malignant, and the term malignancy implies cancer.

Manifestation: the outward sign that an illness is present, a symptom or condition.

Monotherapy: means using only one HIV antiretroviral medication at a time. When HIV medications

were first being developed, people were treated with a single drug like AZT or d4T. This practice took

place in a time when there were very few treatment options and we had not yet found out how to best use

the medications. Anti-HIV monotherapy leads to drug resistance and eventually cross-resistance to an entire

class of drugs. The only time monotherapy should be used today is in the case of treating pregnant women

in developing nations, during labor and delivery, to help reduce the rate of HIV transmission from mother

to child. Otherwise, monotherapy is substandard therapy and should not be prescribed.

Mucous Membrane: the moist layer of tissue lining the digestive, respiratory, urinary and reproductive

tracts—all the body cavities with openings to the outside world except the ears.

Mutation: any alteration, loss, gain or exchange of genetic material within a cell or virus. Mutations

are perpetuated in succeeding generations of that cell or virus. They can occur spontaneously or in

response to environmental factors. HIV mutates at a very rapid rate on its own, which is why developing

a vaccine has been so difficult. Often times, in the presence of HIV medications that aren’t fully suppressing

the virus, mutations can occur that lead to an individual’s virus becoming resistant to the drugs

in that combination. See also Genotype and Resistance.


Natural History of a Disease: the course of a disease when left untreated.

NIH (National Institutes of Health): the federal agency responsible for overseeing government-

sponsored biomedical research. It is divided into 24 institutes and research centers.

NNRTI (Non-Nucleoside Reverse Transcriptase Inhibitor): a member of a class of compounds,

including delavirdine, nevirapine and efavirenz, that acts to directly combine with and block

the action of HIV’s reverse transcriptase. This actions stops the HIV RNA from converting to DNA and

subsequently prevents the infection of the nucleus of the cell by HIV

NRTI (Nucleoside Reverse Transcriptase Inhibitor): the first class of drugs developed to

combat HIV. The drug binds to and blocks the action of HIV reverse transcriptase. Also referred to as

“nukes”, NRTIs include AZT, 3TC, d4T, ddI and abacavir. Some NRTIs have been combined in one pill.

i.e. Combivir (AZT & 3TC) or Trizivir (AZT, 3TC & Abacavir).


Ocular: relating to the eye.

Off-Label: use of a drug for a disease or condition other than that for which it was approved by the

FDA. For example, many doctors prescribe paromomycin (humatin) for cryptosporidiosis, although it is

not approved for treating this disease.

Opportunistic Infection: abbreviated OI, an infection or cancer that occurs especially or exclusively

in persons with weak immune systems due to AIDS, cancer or immunosuppressive drugs or

chemotherapy. KS, PCP, MAC, toxoplasmosis and cytomegalovirus are all examples of opportunistic


Open-Label Trial: a study in which both researchers and participants know what drugs a person is

taking and at what dosages.


Pap Smear: a microscopic examination of the surface cells of the cervix, usually conducted on scrapings

from the cervical opening. This assay is used to detect tissue changes that could be evidence of

STD’s or forerunners of cervical cancer.

Pathogen: any disease-provoking microorganism or material such as a virus, bacterium, protozoan

or fungus.

PCR (Polymerase Chain Reaction) Test: a very sensitive test that measures the presence or

amount of RNA or DNA of a specific organism or virus (for example, HIV or CMV) in the blood or tissue.

PCR tests are used to gauge HIV disease progression and the effect of particular treatments on HIV


Perinatal Transmission: transmission of a pathogen, such as HIV, from mother to baby during or

just before birth. Also called Vertical Transmission.

Pharmacokinetics: the study of how the body absorbs, distributes, metabolizes, and gets rid of

(excretes) drugs. Pharmacokinetics also studies how drugs interact in the body when they’re used together

in the body. For example, ritonavir (Norvir) slows down the metabolism of other protease inhibitors

which means the other drug stays in a person’s blood longer and has more time to do its work. In this

case ritonavir enhances the effectiveness of another protease inhibitor. Sometimes pharmacokinetics is

referred to as “PK.”

Phenotypic Testing/Assay: a test that measures some aspect of an organism's functions, for

example, the amount of a certain drug needed to inhibit the growth of an HIV ISOLATE in a test-tube

culture. If HIV has developed RESISTANCE to a certain drug, then higher than the normally administered

amounts of that drug will be necessary to inhibit viral activity. PHENOSENSE and ANTIVIROGRAM are

commercially available in the United States. See also GENOTYPIC ASSAY.

PICC Line (Peripherally Inserted Central Catheter): a catheter inserted into an arm vein

and used for periods of sometimes up to three months. This catheter does not need to be surgically

implanted and can be inserted by a trained nurse. Individuals with PICC Lines should be watchful of


Placebo: a comparison substance against which experimental drugs are sometimes compared. A

placebo traditionally is an inactive substance resembling the experimental treatment. In placebo-controlled

trials, the control group takes placebo, while the test group takes the experimental drug. Either

group may receive a standard therapy in addition. Many placebo-controlled trials are also double-blinded,

which means that neither doctors nor patients know who is receiving drug or placebo.

Placenta: a temporary organ in the uterus that allows a fetus to receive nutrients, oxygen and other

substances (such as medications) from the mother and to eliminate carbon dioxide and other wastes.

Plasma: the watery, yellowish fluid that carries white and red blood cells and platelets through the circulatory

system. Plasma is prepared for laboratory assays by treating whole blood with an anticoagulant

and then centrifuging the fluid to separate out the cells.

Post-Exposure Prophylaxis (PEP): administering drug treatment to prevent disease in an individual

after exposure to an infectious organism. For example, guidelines have been established for postexposure

prophylaxis of health care providers who have been possibly exposed to HIV through a needle

stick. PEP treatment is also used for known sexual or drug using exposure to HIV. PEP must be started

within just a few hours of exposure to be effective.

Postpartum: after childbirth.

Prognosis: the probable future course of disease in an individual.

Prophylaxis: treatment to prevent the onset of a particular disease (primary prophylaxis) or recurrence

of symptoms in an existing infection that has been brought under control (secondary prophylaxis

or maintenance therapy).

Protease: an enzyme that triggers the breakdown of proteins. HIV’s protease enzyme breaks apart

long strands of viral protein into the separate proteins constituting the viral core and the enzymes it contains.

HIV protease acts as new virus particles are budding off a cell membrane.

Protease Inhibitors: a class of drugs that binds to and blocks HIV protease from splitting new HIV

RNA strands into viable viral particles, ready to exit the host cell and infect a new cell.


Qualitative Assay: a test that determines the presence or absence of a substance.

Quantitative Assay: a test that measures the amount of a substance in a specified sample size.


Randomized Trial: a trial in which the participants are randomly assigned a treatment that could

be the study medication, a standard treatment or placebo. Randomization minimizes the differences

among groups by equally distributing people with particular characteristics among all the trial arms.

Regimen: a prescribed drug treatment plan, specifying which drugs are to be used, in what doses

and on what schedule.

Resistance: reduction in a virus’s sensitivity to a particular drug. Resistance is thought to result mainly

from a genetic mutation. In HIV, such mutations can change the structure of viral enzymes and proteins

so that an antiviral drug cannot bind with them as well as it used to. Resistance detected by searching a

virus’s genetic makeup for mutations is called genotypic resistance. Resistance found by successfully

growing laboratory cultures of the virus in the presence of a drug is called phenotypic resistance. Highlevel

resistance reduces a drug’s virus suppressing activity hundreds of times. Low-level resistance represents

only a few-fold reduction in drug effectiveness. Depending on the toxicity of the drug, low-level

resistance may be overcome by using higher doses of the drug in question or boosting the drug level

with another drug. ie. the use of a small amount of Norvir with Agenerase or within Kaletra boosts the

levels of those drugs much higher.

Retrovirus: a virus made up of RNA that changes to DNA upon entering a cell. This allows the virus

to take over the genetic structure of the cell and turn it into a viral factory.

Reverse Transcriptase (RT): a uniquely viral enzyme that constructs DNA from an RNA template,

which is an essential step in the life-cycle of a retrovirus such as HIV. The RNA based genes of HIV and

other retroviruses must be converted to DNA if they are to integrate into the cellular genetic structure.

RNA (ribonucleic acid): a single-stranded molecule composed of nucleotide sequences. In cells,

RNA transmits the code from the DNA-based genes that instructs the cells’ chemical machinery to produce

structural proteins and enzymes. In retroviruses, an enzyme called reverse transcriptase turns RNA

into DNA after the virus has invaded the cell, allowing the virus to reproduce in the cell.


Salvage Therapy: a therapy used in advanced progression of HIV disease in persons with multiple

mutations to standard treatment regimens. It usually employs multiple drugs that an individual may have

used before and may have some resistance to in an effort to achieve some reduction in viral load for a

period of time.

Sensitivity: the degree to which an organism is affected by a drug.

Seroconversion: development of detectable antibodies to a virus in the blood as a result of infection.

It normally takes several weeks to several months for antibodies to the virus to develop after transmission.

When antibodies to HIV appear in the blood, a person will test positive in the standard ELISA

test for HIV.

Serostatus: the condition of having or not having detectable antibodies to a microbe in the blood as

a result of infection. One may have either a positive or negative serostatus.

Set Point: the rate of HIV replication at steady state, after primary infection. It is usually established

by six months after seroconversion and is evaluated using the viral load assay.

Side Effect: any reaction that results from a drug or therapy. The term usually refers to a negative

event, such as nausea, blood disorders or neuropathy. Experimental drugs must be evaluated for both

short and long term side effects. Also called adverse effect or adverse reaction.

Simian Immunodeficiency Virus (SIV): a retrovirus found in monkeys that is closely related to


STD: sexually transmitted disease. HIV is an STD.

Subcutaneous: below the skin, also refers to injecting medicines directly under the skin.

Supplemental Therapy: added to complete a form of treatment of therapy, similar to complementary

therapy. Very often, supplemental therapy refers to substances like multivitamins and antioxidants

that are taken due to a dietary or medication related deficiency.

Surrogate Marker: a laboratory measurement or physical sign that does not directly show how

patients feel, but rather predicts the likely effect of a medication on their future disease status. CD4 cell

count is an example of a surrogate marker in HIV infection.


Therapeutic Vaccine: A vaccine that is used to treat already HIV infected individuals. These are

not prevention vaccines, but rather a new approach to treating HIV.

TID: a term used on prescriptions to mean, “take three times a day,” from the Latin phrase ter in die.

Toxicity: the harmful side effects of a given drug.

Traditional Medicine: usually refers to Western medical practice.

Treatment Experienced: refers to patients with a history of previous treatment for a particular


Treatment Naive: refers to patients with no history of previous treatment for a particular condition.

Compare Treatment Experienced.


Undetectable: the level below which a test can no longer accurately measure the amount of a substance,

such as HIV RNA, in a person. If a person has “undetectable viral load” it does not mean that

HIV is no longer present, but rather, that the test is not sensitive enough to measure the amount of virus

in the bloodstream.


Vaccine: a vaccine provides long-term immunity against a pathogen by producing an acquired

immune response giving rise to memory cells without causing disease.

Vertical Transmission: transmission of a pathogen such as HIV from mother to fetus or baby during

pregnancy or birth.

Viral Load: the amount of HIV RNA per unit of blood plasma. The amount of free HIV circulating in

the blood. Current viral load tests measure as low as 20 copies per milliliter of blood.

Virology: the study of viruses and viral diseases.

Virulence: the power of a microorganism to cause grave disease or withstand treatment.

Virus: a noncellular pathogen composed essentially of genetic material (DNA or RNA) surrounded by

a protein envelope. Viruses can reproduce only within living cells into which they inject their genetic

material. The viral genes then subvert an infected cell’s normal chemical processes to create new virus

particles, usually killing the cell in the process.


Western Blot: a test for detecting the specific antibodies to HIV in a person’s blood. It commonly is

used to verify positive ELISA tests. A Western Blot test is more reliable than the ELISA, but it is harder

and more costly to perform. All positive HIV antibody tests should be confirmed with a Western Blot test.