Resistance mutation (virology)

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Resistance to a drug

A resistance mutation is a mutation in a virus gene that allows the virus to become resistant to treatment with a particular antiviral drug. The term was first used in the management of HIV, the first virus in which genome sequencing was routinely used to look for drug resistance. At the time of infection, a virus will infect and begin to replicate within a preliminary cell. As subsequent cells are infected, random mutations will occur in the viral genome. [1] When these mutations begin to accumulate, antiviral methods will kill the wild type strain, but will not be able to kill one or many mutated forms of the original virus. At this point a resistance mutation has occurred because the new strain of virus is now resistant to the antiviral treatment that would have killed the original virus. [1] Resistance mutations are evident and widely studied in HIV due to its high rate of mutation and prevalence in the general population. Resistance mutation is now studied in bacteriology and parasitology.

Contents

Mechanisms

Resistance mutations can occur through several mechanisms from single nucleotide substitutions to combinations of amino acid substitutions, deletions and insertions. [1] Over time, these new genetic lines will persist if they become resistant to treatments being used against them. It has been shown that pathogens will favor and become more resistant to treatment in common host genotypes through frequency-dependent selection. [2] Further, strict adherence to a retroviral regimen correlates to a strong decrease in retroviral resistance mutations. [3] There are five classes of drug that are used to treat HIV infection, and resistance mutations can effect the efficacy of these treatments as well.

In Other Viruses

Resistance mutations are found and become problematic in many viruses other than HIV. Notable examples of such viruses include the herpes simplex virus and hepatitis B virus. [9] In the herpes virus, drugs mainly target the viral DNA polymerase. As a result, mutations in the viral DNA polymerase that make it resistant to these drugs are selected for, which ultimately can cause complete resistance of the treatment. In hepatitis B, nucleoside and nucleotide analogs are used to cause early termination of viral transcription. Mutations in viral reverse transcriptase can cause the enzyme to not incorporate these nonfunctional analogs, in favor for their natural counterparts. If this mutation occurs, transcription will not be halted, and viral proteins can be created.

Research Applications

Related Research Articles

<span class="mw-page-title-main">Retrovirus</span> Family of viruses

A retrovirus is a type of virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. After invading a host cell's cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern, thus retro (backwards). The new DNA is then incorporated into the host cell genome by an integrase enzyme, at which point the retroviral DNA is referred to as a provirus. The host cell then treats the viral DNA as part of its own genome, transcribing and translating the viral genes along with the cell's own genes, producing the proteins required to assemble new copies of the virus. Many retroviruses cause serious diseases in humans, other mammals, and birds.

<span class="mw-page-title-main">Antiviral drug</span> Medication used to treat a viral infection

Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Antiviral drugs are one class of antimicrobials, a larger group which also includes antibiotic, antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies. Most antivirals are considered relatively harmless to the host, and therefore can be used to treat infections. They should be distinguished from virucides, which are not medication but deactivate or destroy virus particles, either inside or outside the body. Natural virucides are produced by some plants such as eucalyptus and Australian tea trees.

The management of HIV/AIDS normally includes the use of multiple antiretroviral drugs as a strategy to control HIV infection. There are several classes of antiretroviral agents that act on different stages of the HIV life-cycle. The use of multiple drugs that act on different viral targets is known as highly active antiretroviral therapy (HAART). HAART decreases the patient's total burden of HIV, maintains function of the immune system, and prevents opportunistic infections that often lead to death. HAART also prevents the transmission of HIV between serodiscordant same-sex and opposite-sex partners so long as the HIV-positive partner maintains an undetectable viral load.

Protease inhibitors (PIs) are medications that act by interfering with enzymes that cleave proteins. Some of the most well known are antiviral drugs widely used to treat HIV/AIDS, hepatitis C and COVID-19. These protease inhibitors prevent viral replication by selectively binding to viral proteases and blocking proteolytic cleavage of protein precursors that are necessary for the production of infectious viral particles.

Reverse-transcriptase inhibitors (RTIs) are a class of antiretroviral drugs used to treat HIV infection or AIDS, and in some cases hepatitis B. RTIs inhibit activity of reverse transcriptase, a viral DNA polymerase that is required for replication of HIV and other retroviruses.

<span class="mw-page-title-main">Lamivudine</span> Chemical compound

Lamivudine, commonly called 3TC, is an antiretroviral medication used to prevent and treat HIV/AIDS. It is also used to treat chronic hepatitis B when other options are not possible. It is effective against both HIV-1 and HIV-2. It is typically used in combination with other antiretrovirals such as zidovudine, dolutegravir, and abacavir. Lamivudine may be included as part of post-exposure prevention in those who have been potentially exposed to HIV. Lamivudine is taken by mouth as a liquid or tablet.

<span class="mw-page-title-main">Nevirapine</span> Chemical compound

Nevirapine (NVP), sold under the brand name Viramune among others, is a medication used to treat and prevent HIV/AIDS, specifically HIV-1. It is generally recommended for use with other antiretroviral medications. It may be used to prevent mother to child spread during birth but is not recommended following other exposures. It is taken by mouth.

This is a list of AIDS-related topics, many of which were originally taken from the public domain U.S. Department of Health Glossary of HIV/AIDS-Related Terms, 4th Edition.

<span class="mw-page-title-main">Efavirenz</span> Antiretroviral medication

Efavirenz (EFV), sold under the brand names Sustiva among others, is an antiretroviral medication used to treat and prevent HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used for prevention after a needlestick injury or other potential exposure. It is sold both by itself and in combination as efavirenz/emtricitabine/tenofovir. It is taken by mouth.

<span class="mw-page-title-main">Nucleoside analogue</span> Biochemical compound

Nucleoside analogues are nucleosides which contain a nucleic acid analogue and a sugar. Nucleotide analogs are nucleotides which contain a nucleic acid analogue, a sugar, and a phosphate group with one to three phosphates.

<span class="mw-page-title-main">Lamivudine/zidovudine</span> Combination drug for HIV

Lamivudine/zidovudine, sold under the brand name Combivir among others, is a fixed-dose combination antiretroviral medication used to treat HIV/AIDS. It contains two antiretroviral medications, lamivudine and zidovudine. It is used together with other antiretrovirals. It is taken by mouth twice a day.

<span class="mw-page-title-main">Etravirine</span> Also called Intelence is a drug used for the treatment of HIV

Etravirine is a drug used for the treatment of HIV. Etravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI). Unlike the currently available agents in the class, resistance to other NNRTIs does not seem to confer resistance to etravirine. Etravirine is marketed by Janssen, a subsidiary of Johnson & Johnson. In January 2008, the Food and Drug Administration approved its use for patients with established resistance to other drugs, making it the 30th anti-HIV drug approved in the United States and the first to be approved in 2008. It was also approved for use in Canada on April 1, 2008.

<span class="mw-page-title-main">Rilpivirine</span> HIV treatment

Rilpivirine, sold under the brand names Edurant and Rekambys, is a medication, developed by Tibotec, used for the treatment of HIV/AIDS. It is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with higher potency, longer half-life and reduced side-effect profile compared with older NNRTIs such as efavirenz.

<span class="mw-page-title-main">Elvucitabine</span> Medication

Elvucitabine is an experimental nucleoside reverse transcriptase inhibitor (NRTI), developed by Achillion Pharmaceuticals, Inc. for the treatment of HIV infection.

Non-nucleoside reverse-transcriptase inhibitors (NNRTIs) are antiretroviral drugs used in the treatment of human immunodeficiency virus (HIV). NNRTIs inhibit reverse transcriptase (RT), an enzyme that controls the replication of the genetic material of HIV. RT is one of the most popular targets in the field of antiretroviral drug development.

Many major physiological processes depend on regulation of proteolytic enzyme activity and there can be dramatic consequences when equilibrium between an enzyme and its substrates is disturbed. In this prospective, the discovery of small-molecule ligands, like protease inhibitors, that can modulate catalytic activities has an enormous therapeutic effect. Hence, inhibition of the HIV protease is one of the most important approaches for the therapeutic intervention in HIV infection and their development is regarded as major success of structure-based drug design. They are highly effective against HIV and have, since the 1990s, been a key component of anti-retroviral therapies for HIV/AIDS.

Discovery and development of nucleoside and nucleotide reverse-transcriptase inhibitors began in the 1980s when the AIDS epidemic hit Western societies. NRTIs inhibit the reverse transcriptase (RT), an enzyme that controls the replication of the genetic material of the human immunodeficiency virus (HIV). The first NRTI was zidovudine, approved by the U.S. Food and Drug Administration (FDA) in 1987, which was the first step towards treatment of HIV. Six NRTI agents and one NtRTI have followed. The NRTIs and the NtRTI are analogues of endogenous 2´-deoxy-nucleoside and nucleotide. Drug-resistant viruses are an inevitable consequence of prolonged exposure of HIV-1 to anti-HIV drugs.

The first human immunodeficiency virus (HIV) case was reported in the United States in the early 1980s. Many drugs have been discovered to treat the disease but mutations in the virus and resistance to the drugs make development difficult. Integrase is a viral enzyme that integrates retroviral DNA into the host cell genome. Integrase inhibitors are a new class of drugs used in the treatment of HIV. The first integrase inhibitor, raltegravir, was approved in 2007 and other drugs were in clinical trials in 2011.

Bictegravir/emtricitabine/tenofovir alafenamide, sold under the brand name Biktarvy, is a fixed-dose combination antiretroviral medication for the treatment of HIV/AIDS. One tablet, taken orally once daily, contains 50 mg bictegravir, 200 mg emtricitabine, and 25 mg tenofovir alafenamide. It was approved for use in the United States in February 2018, and for use in the European Union in June 2018.

In the management of HIV/AIDS, HIV capsid inhibitors are antiretroviral medicines that target the capsid shell of the virus. Most current antiretroviral drugs used to treat HIV do not directly target the viral capsid. These have also been termed "Capsid-targeting Antivirals", "Capsid Effectors", and "Capsid Assembly Modulators (CAMs)". Because of this, drugs that specifically inhibit the HIV capsid are being developed in order to reduce the replication of HIV, and treat infections that have become resistant to current antiretroviral therapies.

References

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