- What is antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection?
- What is HIV infection?
- What ART drug classes prevent entry of human immunodeficiency virus (HIV) into the human immune cell?
- How do ART drugs prevent HIV entry into the human cell?
- What ART drugs prevent HIV entry into the human immune cell?
What is antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection?
Antiretroviral therapy (ART) is a complete treatment regimen for human immunodeficiency virus (HIV) infection, with a combination of three or more classes of drugs. Each drug class targets the virus at a different stage in its replication cycle, which improves the chances of controlling the infection.
HIV infection has no cure but ART can contain the viral growth and keep the patient healthy and active for many years. ART also helps minimize the chances of transmission. Interrupting or stopping ART can lead to increase in viral load, and virus mutations that develop resistance to treatment.
What is HIV infection?
HIV infection is caused by a virus that infects human immune cells known as T-cells. HIV infection spreads through certain bodily fluids such as blood, semen, vaginal fluids or breast milk. The virus enters into the T-cell and uses its cell machinery to replicate itself, destroying the host cell in the process.
In its later stages, HIV infection can lead to acquired immune deficiency syndrome (AIDS), when the immune system is so weakened that it is unable to fight even common infections.
What ART drug classes prevent entry of human immunodeficiency virus (HIV) into the human immune cell?
HIV goes through several stages in its life cycle. It enters the T-cell and releases certain enzymes which enable its integration with the host cell, and creation of more viral particles.
Most of the drugs developed in the early days of ART act on the virus after it enters into the T-cell by interfering with the integration and replication activities.
The newest drugs attack the virus at the stage when it binds to the T-cell and prevent it from penetrating the cell membrane. There are three classes of drugs which attack the virus in different ways, before it enters the immune cell (extracellular):
- Fusion inhibitor: Introduced in 2003, the fusion inhibitor stops the HIV from fusing with the immune cell’s membrane, preventing entry.
- Chemokine receptor antagonist (CCR5 antagonist): Developed in 2007, the chemokine receptor antagonist blocks entry of certain specific strains of HIV, which attach to a particular protein on the immune cell’s surface known as chemokine receptor 5 (CCR5).
- Post-attachment inhibitor (Entry inhibitor): The latest ART drug to be approved by FDA in 2018, the post-attachment inhibitor prevents the viral envelope fusion with the cell membrane after it binds to the cell.
How do ART drugs prevent HIV entry into the human cell?
HIV is a microscopic particle that has a single strand of genetic matter known as RNA, which cannot reproduce on its own. The RNA is covered in an envelope known as capsid which has two glycoproteins (a kind of protein molecule that incorporates a sugar molecule), gp120 and gp41, embedded in its surface.
The essential steps for the HIV to fuse its capsid with the T-cell membrane and enter into the cell are:
- The HIV glycoprotein gp120 binds to the CD4 receptor on the T-cell’s surface.
- The CD4-gp120 complex undergoes a structural change with a loop that attaches to one of the other two receptors (CCR5 or CXCR4) found on the T-cell surface.
- The second glycoprotein gp41 inserts itself into the cell membrane.
- The capsid merges with the cell membrane and the RNA emerges from the capsid and enters the fluid inside the T-cell (cytoplasm).
The three classes of entry inhibitor drugs block the viral fusion and entry process in different ways.
- Fusion inhibitor: The fusion inhibitor binds to the HIV glycoprotein gp41, alters its structure and prevents the completion of fusion.
- Chemokine receptor antagonist: The chemokine receptor antagonist binds to the CCR5 receptor and stops the HIV’s gp120 from attaching to it. This drug class works selectively on certain HIV strains such as R5 that attach to chemokine receptor CCR5 (CCR5-tropic virus). The chemokine receptor antagonist is ineffective against those virus strains that bind with CXCR4. The patient undergoes a test to determine the virus type before taking this drug class.
- Post-attachment inhibitor: The post-attachment inhibitor binds to the T-cell’s CD4 receptor and alters its structure. The structural change in the CD4 stops further chain reactions which would otherwise lead to the HIV’s fusion and entry into the T-cell.
What ART drugs prevent HIV entry into the human immune cell?
Currently, one FDA-approved drug is available in each class of drugs that work at the fusion and entry stage of the HIV. Following is the list of the drugs with some of their side effects.
Taken as an injection in the skin tissue (subcutaneous) twice daily, approved only for antiretroviral treatment-experienced patients with drug resistance.
Side effects include:
- Injection-site reactions such as:
- Hypersensitivity reactions (rare)
Chemokine receptor antagonist (CCR5 antagonist)
Available as tablets only for patients with CCR5-tropic virus resistant to multiple antiretroviral medications.
Side effects include:
- Abdominal pain
- Upper respiratory tract infection
- Musculoskeletal symptoms
- Liver toxicity
- Orthostatic hypotension (low blood pressure that occurs during change of posture, when standing up from sitting or lying down)
Administered as IV infusions every two weeks, approved only for antiretroviral treatment-experienced patients with drug resistance.
Side effects include:
- Immune reconstitution syndrome: (Rare) Development of inflammatory symptoms caused by the response of the immune system that has recovered with antiretroviral therapy, which starts attacking other pre-existing, latent bacterial or viral infections. These symptoms usually resolve in a few weeks.
Three classes of drugs developed to treat HIV/AIDS work by preventing entry of the human immunodeficiency virus into the immune cells, preventing the virus from replicating and destroying the immune system. These classes (which are typically combined with two or more other HIV drugs) include fusion inhibitors, chemokine receptor antagonist (CCR5 antagonist) and Post-attachment inhibitor (entry inhibitor).
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Related Disease Conditions
HIV Early Signs and Stages
HIV (human immunodeficiency virus) weakens your immune system. Some people with HIV don’t have any symptoms, but those that do may experience mononucleosis-like or flu-like symptoms. There are 3 stages of HIV.
HIV and AIDS
Second Source article from WebMD
How Long Can You Live with HIV?
HIV stands for human immunodeficiency virus. If someone has HIV it means that they have been diagnosed with the HIV infection. AIDS (acquired immune deficiency syndrome); however, is the most advanced or final stage of the HIV infection. In the case of an untreated HIV infection, the overall mortality rate is more than 90%. The average time from infection to death is eight to ten years.
Human Immunodeficiency Virus (HIV)
HIV (human immunodeficiency virus) infection left untreated causes AIDS (acquired immunodeficiency syndrome). The human immunodeficiency virus (HIV) is a type of virus called a retrovirus, which can infect humans when it comes in contact with tissues that line the vagina, anal area, mouth, or eyes, or through a break in the skin. HIV infection is generally a slowly progressive disease in which the virus is present throughout the body at all stages of the disease. Three stages of HIV infection have been described. The initial stage of infection (primary infection), which occurs within weeks of acquiring the virus, often is characterized by the flu- or mono-like illness that generally resolves within weeks. The stage of chronic asymptomatic infection (meaning a long duration of infection without symptoms) lasts an average of eight to 10 years without treatment. The stage of symptomatic infection, in which the body's immune (or defense) system has been suppressed and complications have developed, is called the acquired immunodeficiency syndrome (AIDS). The symptoms are caused by the complications of AIDS, which include one or more unusual infections or cancers, severe loss of weight, and intellectual deterioration (called dementia). When HIV grows (that is, by reproducing itself), it acquires the ability to change (mutate) its own structure. These mutations enable the virus to become resistant to previously effective drug therapy. The goals of drug therapy are to prevent damage to the immune system by the HIV virus and to halt or delay the progress of the infection to symptomatic disease. Therapy for HIV includes combinations of drugs that decrease the growth of the virus to such an extent that the treatment prevents or markedly delays the development of viral resistance to the drugs. The best combination of drugs for HIV are those that effectively suppress viral replication in the blood and also are well tolerated and simple to take so that people can take the medications consistently without missing doses.
What Is the Difference Between HIV-1 and HIV-2?
There are two main types of the human immunodeficiency virus (HIV), HIV-1 and HIV-2. HIV-1 is the most common type of HIV and accounts for 95% of all infections, whereas HIV-2 is relatively uncommon and less infectious. HIV-2 is mainly concentrated in West Africa, is less deadly and progresses more slowly.
How Long Does It Take to See Signs of HIV?
The signs and symptoms of HIV may first appear within two to four weeks of infection. The stage in which the symptoms appear is called the stage of acute HIV infection. The symptoms appear due to the resistance or fight of the immune system against HIV. Early diagnosis and treatment of HIV gets the best results.
What Are the Four Stages of HIV?
The World Health Organization (WHO) classifies human immunodeficiency virus (HIV) into four stages. Stage 1 (HIV infection): The CD4+ cell count is at least 500 cells per microliter. Stage 2 (HIV infection): The CD4+ cell count is 350 to 499. Stage 3 (advanced HIV disease or AHD): The CD4+ cell count is 200 to 349. Stage 4 (Acquired immunodeficiency syndrome [AIDS]): The CD4+ cell count is less than 200.
How Long Does It Take to Notice Signs of HIV?
HIV (human immunodeficiency virus) is a virus that attacks and damages the cells of the immune system in the body. If left untreated, HIV can lead to the AIDS (acquired immunodeficiency syndrome) disease. AIDS is the final stage of HIV infection which occurs when the body’s immune system is severely damaged because of the virus and unusual infections result. Untreated, HIV infection has a mortality of 90%.
HIV vs. AIDS
Human immunodeficiency virus causes HIV infection. Acquired immunodeficiency syndrome (AIDS) is a condition that results after HIV has extensively damaged a person's immune system. Risk factors for HIV and AIDS include use of contaminated needles or syringes, unprotected sex, STDs, receiving a blood transfusion prior to 1985 in the United States, having many sex partners, and transmission from a mother to her child.
Can HIV be Cured Naturally?
HIV stands for human immunodeficiency virus. If someone has HIV it means that they have been diagnosed with the HIV infection. AIDS (acquired immune deficiency syndrome); however, is the most advanced or final stage of the HIV infection. It is important to get tested for HIV in the early stages of infection to minimize the damage to the immune system. Successful treatment aims to reduce HIV load to a level that is harmless to the body.
How Do You Feel When You Have HIV?
About four weeks after contracting HIV (human immunodeficiency virus), you may experience flu-like symptoms including fever, rash, sore throat, nausea, swollen glands and achy joints. You may remain symptomless for some time, however. That doesn't mean you don't need treatment; HIV can quickly progress into AIDS, in which the immune system collapses and you die of a secondary cancer or infection.
What Is Usually the First Sign of HIV?
Human immunodeficiency virus (HIV) attacks the cells of the immune system, leading to AIDS and death if left untreated. The first signs of the human immunodeficiency virus infection are flu-like symptoms, which mainly start around two to four weeks after getting HIV. This stage is known as acute HIV infection.
HIV Medications List and Drug Charts
The ultimate goal of HIV treatment is getting the viral load down below detectable levels. As long as those viral load and antibody levels are below a proscribed range, people with HIV can stave off AIDS and other serious symptoms. Antiviral treatment options usually include combinations of two NRTIs, often referred to as "nucs," and a third drug, typically being a boosted protease inhibitor, a NNRTI, often called "non-nucs," and integrase strand transfer inhibitors.
HIV/AIDS Infection Transmission and Prevention
HIV (human immunodeficiency virus) is spread through contact with genital fluids or blood of an infected person. The spread of HIV can occur when these secretions come in contact with tissues such as those lining the vagina, anal area, mouth, eyes (the mucus membranes), or with a break in the skin, such as from a cut or puncture by a needle.
HIV/AIDS Testing: Diagnosis and Monitoring
HIV/AIDS diagnosis and monitoring have come a long way from the days when a diagnosis was a death sentence. Crucial parts of the effective treatment regimens developed in the last 40 years are consistent monitoring of the viral load (the amount of virus in the blood), and the immune cell count, which function as biological markers of the disease’s progression. Doctors also must test for drug resistance.
HIV/AIDS Facts: What Is HIV?
HIV (human immunodeficiency virus) is the precursor infection to AIDS (acquired immunodeficiency syndrome). HIV is transmitted through blood and genital secretions; most people get it through sexual contact or sharing needles for illegal IV drug use. HIV can be controlled by a strict drug regimen, but left unchecked, it leads to AIDS. In AIDS, the immune system collapses and the body falls prey to secondary, opportunistic infections and cancers that typically kill the person.
What Are the Side Effects of HIV Medications?
It’s important to know the potential side effects of all the drugs you take to control your HIV infection, as well as potential drug interactions. All of the NNRTIs (nonnucleoside analogue reverse transcriptase inhibitors), for example, are associated with important drug-drug interactions so they must be used with caution in patients on other medications. Learn more about the side effects of the drugs in standard treatment regimens.
When should you start HIV medication?
Nearly everyone who is infected with HIV (human immunodeficiency virus) should start antiviral medication therapy as soon as they are diagnosed. Older guidelines recommended delaying treatment to help reduce the potential for drug side effects and viral resistance to treatment. Current thinking theorizes that early treatment may preserve more of the body's immune function.
Treatment & Diagnosis
Medications & Supplements
- Symtuza (darunavir, cobicistat, emtricitabine, and tenofovir alafenamide)
- Valcyte (valganciclovir hydrochloride)
- Dovato (dolutegravir and lamivudine)
- Prezcobix (darunavir and cobicistat)
- Trogarzo (ibalizumab-uiyk)
- enfuvirtide - injection, Fuzeon
- Stribild (elvitegravir, cobicistat, emtricitabine, tenofovir disoproxil fumarate)
- maraviroc, Selzentry
- Prezista (darunavir)
- Triumeq (abacavir, dolutegravir, and lamivudine)
- Mycobutin (rifabutin)
- Pifeltro (doravirine)
- Epzicom (abacavir sulfate and lamivudine)
- Side Effects of Trizivir (abacavir, lamivudine, zidovudine)
- Enfuvirtide (Fuzeon)
Prevention & Wellness
- Newly Diagnosed with HIV/AIDS
- Human Immune Deficiency Virus (HIV/AIDS) Specific References
- HIV, AIDS, and Older People
- HIV: The Hidden Epidemic
- HIV and Tuberculosis - Facts
- AIDS & HIV...Maybe Forgotten, Not Gone from the USA!
- FDA Approves a Once Daily Protease Inhibitor for HIV Infection
- HIV: The Truth About, New HIV Test
- HIV/AIDS - World Trends
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