Antivirals
Antivirals are a class of medications used to treat viral infections by inhibiting the replication of viruses or boosting the body's immune response to the infection. They can target specific viruses or have a broad-spectrum effect against multiple types of viruses. Antivirals are important in managing viral diseases such as influenza, HIV, herpes, and hepatitis.
7 Key excerpts on "Antivirals"
eBook - ePub- Michael J. Neal(Author)
- 2020(Publication Date)
- Wiley-Blackwell(Publisher)
...41 Antiviral drugs Viruses are intracellular parasites that lack independent metabolism and can replicate only within living host cells. Because their replication cycle is so intimately connected with the metabolic processes of the host cell, it has proved difficult to produce drugs that are selectively toxic to viruses. For this reason, vaccines have been the main method for controlling viral infections (e.g. poliomyelitis, rabies, yellow fever, measles, mumps, rubella). However, the human immunodeficiency virus (HIV) pandemic stimulated a search for new antiviral drugs and in the past 15 years or so many effective antiviral drugs have been produced. Antiviral drugs have transformed the treatment of several diseases, notably those caused by HIV and herpes virus infections. Viral replication involves several steps (centre, figure). The first stage involves fusion of the virus with the host cell, followed by entry and uncoating of the virus. Enfuvirtide (used in AIDS) and immunoglobulins (top right) inhibit penetration of the cell by the virus, while amantadine (right, shaded) inhibits the uncoating of influenza‐A virus once it has entered the cell. The neuraminidase inhibitors (centre, right), e.g. oseltamivir, prevent the exit of new virions from the host cell. Many antiviral drugs (left) interfere with viral nucleic acid synthesis. Drugs that act by inhibiting viral DNA polymerase, e.g. aciclovir (top, left), are selectively antiviral because they are inactive until phosphorylated by enzymes that are preferentially synthesized by the virus. Aciclovir is used in the treatment of herpes virus infections. Antiretroviral (ARV) drugs (middle left, shaded) are used to suppress the replication of HIV in patients with AIDS. Resistance to single drugs develops rapidly but the development of combined ARV therapy regimens in the late nineties transformed a progressive (fatal) disease into a chronic manageable illness...
eBook - ePub- Ruben Vardanyan, Victor Hruby(Authors)
- 2006(Publication Date)
- Elsevier Science(Publisher)
...36 Antiviral Drugs Publisher Summary Antiviral drugs are a class of medication used specifically for treating viral infections. Specific Antivirals are used for specific viruses. Viruses cause more diseases than any other group of parasites. They can cause blindness, deafness, paralysis, mental retardation, various birth defects, and in at least a few plants and animals, cancer. Of all the most well-known viral diseases, the ones that should be stated are measles, mumps, smallpox, chicken pox, influenza, poliomyelitis, and yellow fever. A virus can contain either ribonucleic acid or deoxyribonucleic acid, but it never contains both of them together. Currently, amantadine, vidarabine, trifluridine, idoxuridine, sciclovir, ribavirin, and zidovudine are used as antiviral drugs. The mechanism of antiviral activity consists of its transformation to triphosphate and subsequent inhibition of viral DNA synthesis. An analysis of the mechanisms of action of existing and used viral drugs permits the conclusion to be made that they can increase resistance of the cell to a virus (interferons), suppress adsorption of the virus in the cell or its diffusion into the cell, and the process of its “deproteinization” in the cell (amantadine) as well as antimetabolites that inhibit the synthesis of nucleic acids. Antiviral drugs are a class of medication used specifically for treating viral infections. Like antibiotics, specific Antivirals are used for specific viruses. Viruses cause more diseases than any other group of parasites. They can cause blindness, deafness, paralysis, mental retardation, various birth defects, and in at least a few plants and animals, cancer. Of all the most well-known viral diseases, the ones that should be stated are measles, mumps, smallpox, chicken pox, influenza, poliomyelitis, and yellow fever. There is suspicion that viruses are the cause of multiple sclerosis, Hodgkin’s disease, Down’s syndrome, and possibly even schizophrenia...
eBook - ePub- Jane Flint, Vincent R. Racaniello, Glenn F. Rall, Theodora Hatziioannou, Anna Marie Skalka(Authors)
- 2020(Publication Date)
- ASM Press(Publisher)
...This paucity reflects the many challenges that must be met in drug development. However, when available, Antivirals can have a major impact on human health. Because of their medical importance, most of our antiviral drugs are directed against infections with human immunodeficiency virus type 1, herpesviruses, and hepatitis viruses. In these cases, literally millions of lives have been saved by use of antiviral drugs. One major limitation in antiviral drug development is the requirement for a high degree of safety. This restriction can be difficult to surmount because virus reproduction depends on cellular functions: a compound that blocks a pathway that is critical for the virus can also have deleterious effects on the host cell. Another requirement is that antiviral compounds must be extremely potent at the site of infection: even modest reproduction in the presence of an inhibitor provides the opportunity for selection of resistant mutants. Achieving sufficient potency to block viral reproduction completely is remarkably challenging. Other limitations can be imposed by the difficulty in propagating some medically important viruses in the laboratory (e.g., hepatitis B virus and papillomaviruses) and the lack of small-animal models that faithfully reproduce infection in humans (such as measles and hepatitis C viruses). Lack of rapid diagnostic reagents has also hampered the development and marketing of antiviral drugs to treat many acute viral diseases, even when effective therapies are available. Many acute virus infections are of short duration, and by the time the patient feels ill, it is too late to impact clinical disease. Economic considerations also play a role: pharmaceutical companies mainly focus on viral diseases that can provide substantial profits. A Brief History of Antiviral Drug Discovery The first large-scale effort to find antiviral compounds began in the early 1950s with a search for inhibitors of smallpox virus reproduction...
eBook - ePub- Reeti Khare(Author)
- 2019(Publication Date)
- ASM Press(Publisher)
...19.5). 3. Viral replication: There are three main ways Antivirals interfere with viral replication (Fig. 19.1). Figure 19.1. Mechanisms of Antivirals against viral replication. Direct binding to replicative enzymes, like polymerases. This can be a highly specific drug target because many viruses require virus-specific enzymes for replication. Nucleotide or nucleoside analogs: Nucleotides are substrates for polymerases, so mimics are used to block or disrupt nucleic acid synthesis and prevent further nucleotides from being added. Introducing mutations: A large number of errors incorporated during viral replication can cause the virus population to degenerate. 4. Viral proteins and assembly: Antivirals that interfere with viral assembly increase the proportion of nonviable (noninfectious) virions. For example, viral protease is an important drug target because it is used to cleave polyproteins into individual proteins for structure and replication. Boosters (e.g., ritonavir) can be used with HIV protease inhibitors to decrease clearance of protease inhibitors and prolong their half-lives. 5. Release of viral particles: Viruses that are prevented from being released from cells cannot go on to infect new cells (see Fig. 19.4). 6. Activating the immune response (immunomodulators). Some therapies (e.g., interferons) trigger the immune system’s natural defenses against viruses. II. Antivirals THAT CAN COVER SEVERAL VIRUS TYPES. (Table 19.1 ; see also Table 19.11) Table 19.1. Antivirals that can cover several virus types 1. Interferons: These are cytokines that are naturally produced during the innate immune response and interfere with virus replication. Mechanism: Interferons have antiviral, antiproliferative, and immunomodulatory effects and trigger signaling cascades to activate other immune system components (Fig...
eBook - ePub- Pulok K. Mukherjee(Author)
- 2015(Publication Date)
- Elsevier(Publisher)
...Several reports on the discovery of new drugs from traditional medicines [7 – 12] indicated the use of medicinal plants as a potential source for antiviral drug development [1, 7 – 9]. Several reports indicated that a wide variety of phytochemicals, including alkaloids, flavonoids, terpenoids, polyphenolics, coumarins, lignans, have therapeutic applications [4 – 12] due to their interferences on viral entry or replication, along with their antioxidative properties [ 6, 9, 13 ]. Different in vitro and in vivo bioassays on phytochemicals lead to the identification of potential antiviral molecules. In this chapter, we will summarize the scientific approaches used to validate potential “antiviral leads” against selected genetically and functionally diverse viral families, from crude extracts to pure compounds. In-depth studies on some common in vitro antiviral assays with testing of efficacies, modes, and molecular mechanisms of action will be described here with in vivo methods against a few selected viruses. Viral infection control strategies include (1) public health measures to minimize the risk of infection, (2) vaccination to the exposed individuals, and (3) antiinfective drugs for infected individuals. Public health measures such as safe drinking water can prevent Polio and Rota virus infections, while pest control can prevent arthropod and rodent-borne yellow fever, dengue, encephalitis, and hanta and arena viruses. However, to provide these benefits to the people of underdeveloped and developing world is a challenge. A second challenge is to discover means to control airborne respiratory infections. As public health measures are never totally effective, vaccination is a second strategy...
eBook - ePubInfectious
Pathogens and How We Fight Them
- John S. Tregoning(Author)
- 2021(Publication Date)
- Oneworld Publications(Publisher)
...Nearly 67% of the world’s population under fifty has HSV-1, making it one of the most common sexually transmitted infections. Figure 13 The viral life cycle and how Antivirals work: Antiviral drugs target different stages of the viral ‘life’ cycle. A. Starting at entry, some drugs stop the virus ever getting into the cell. B. Other drugs mimic the building blocks of nucleic acid and stop the virus making more copies of its genes – these are called NRTIs (nucleoside reverse transcriptase inhibitors) in the context of HIV. C. A third class of drugs stops the virus making the proteins it needs to build itself. Another viral infection that can cause disfigurement is human papillomavirus (HPV), which causes warts and verrucas. HPV warts are commonly treated with salicylic acid (the main component of Bazooka!), which is loosely antiviral but much less focused than other drugs. Salicylic acid destroys the infected tissue, hopefully taking out the virus at the same time. Treating viral infections by killing the tissue can also be done with something as crude as duct tape; other options include freezing them off (cryotherapy) and cutting them off (surgery). The difference between salicylic acid and acyclovir is the specificity for the virus. Salicylic acid acts like a blunderbuss and acyclovir more like a laser. Acyclovir laid the groundwork for a new generation of rationally designed drugs, pioneered by Trudy Elion and Howard Schaeffer at Burroughs Wellcome in the US. Trudy Elion is the grande dame of antiviral drugs. She graduated in chemistry in 1937 but as a female scientist was unable to find a research job, so she had to save up to do a master’s degree part-time while working as a schoolteacher. Being a woman also prevented her from getting PhD funding, but luckily for the world she got a job working at Wellcome in 1944, exploring nucleotide analogues. At Wellcome she worked with George Hitchings, with whom she shared the Nobel Prize in 1988...
- G. Baskar, K. Sathish Kumar, K. Tamilarasan(Authors)
- 2020(Publication Date)
- Bentham Science Publishers(Publisher)
...Enzyme Inhibition Applications in Treatment of Human Viral Diseases Subasree Sekar, P.K. Praveen Kumar *, Arthi Udhayachandran Department of Biotechnology, Sri Venkateswara College of Engineering (Autonomous), Sriperumbudur Tk – 602117, Tamilnadu, India Abstract Enzyme inhibitor molecules are used for the development of antiviral drugs. Understanding the mechanisms of enzyme inhibitors are needed for the treatment of HIV, Chikungunya, Dengue, Ebola, Influenza, and Nipah viral diseases. Inhibition of viral entry and its replication in the host cell was the most prominent mode of action against these viruses. In this chapter, the detailed list of plant compounds to be used as drugs for the treatment of above viral diseases through targeting of enzymes, reverse transcriptase, and RNA-dependent RNA polymerase is explained. Recent advancements such as emerging technologies, Next Generation Sequencing, and CRISPR used as an effective approach for the diagnosis, treatment, and alleviation of viral disease progression, are explained. Keywords: Antiviral drugs, CRISPR, Enzyme inhibitors, Next Generation Sequencing, Reverse transcriptase, RNA-dependent RNA polymerase. * Corresponding author Praveen Kumar P.K: Department of Biotechnology, Sri Venkateswara College of Engineering (Autonomous), Sriperumbudur Tk – 602117, Tamilnadu, India; Tel: +919444495008; Fax: +914427162462; Email: [email protected] INTRODUCTION Enzymes are biocatalyst that accelerates the chemical reactions. Enzyme inhibitors are chemical compounds with a low molecular weight that may scale back or completely inhibit the enzyme catalytic activity reversibly or irreversibly (permanently). An enzyme-inhibitor complex is formed once the enzyme is bound to the inhibitor. However, the complex is not formed if the enzyme is not bound...
