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.
Nucleoside analogues are structural analogues of a nucleoside, which normally contain a nucleobase and a sugar. Nucleotide analogues are analogues of a nucleotide, which normally has one to three phosphates linked to a nucleoside. Both types of compounds can deviate from what they mimick in a number of ways, as changes can be made to any of the constituent parts. They are related to nucleic acid analogues.
DC-SIGN also known as CD209 is a protein which in humans is encoded by the CD209 gene.
Viral infectivity factor, or Vif, is an accessory protein found in HIV and other lentiviruses. Its role is to disrupt the antiviral activity of the human enzyme APOBEC by targeting it for ubiquitination and cellular degradation. APOBEC is a cytidine deaminase enzyme that mutates viral nucleic acids.
APOBEC3G is a human enzyme encoded by the APOBEC3G gene that belongs to the APOBEC superfamily of proteins. This family of proteins has been suggested to play an important role in innate anti-viral immunity. APOBEC3G belongs to the family of cytidine deaminases that catalyze the deamination of cytidine to uridine in the single stranded DNA substrate. The C-terminal domain of A3G renders catalytic activity, several NMR and crystal structures explain the substrate specificity and catalytic activity.
Cyanovirin-N (CV-N) is a protein produced by the cyanobacterium Nostoc ellipsosporum that displays virucidal activity against several viruses, including human immunodeficiency virus (HIV). A cyanobacterial protein called cyanovirin-N (CV-N) has strong anti-human immunodeficiency virus (HIV) neutralizing properties. The virucidal activity of CV-N is mediated through specific high-affinity interactions with the viral surface envelope glycoproteins gp120 and gp41, as well as to high-mannose oligosaccharides found on the HIV envelope. In addition, CV-N is active against rhinoviruses, human parainfluenza virus, respiratory syncytial virus, and enteric viruses. The virucidal activity of CV-N against influenza virus is directed towards viral haemagglutinin.
Entry inhibitors, also known as fusion inhibitors, are a class of antiviral drugs that prevent a virus from entering a cell, for example, by blocking a receptor. Entry inhibitors are used to treat conditions such as HIV and hepatitis D.
Griffithsin is a protein isolated from the red algae Griffithsia. It has a 121-amino acid sequence which exhibits a Jacalin-like lectin fold. Several structures of this protein have been solved by X-ray crystallography and deposited in the PDB. It has been shown in vitro to be a highly potent HIV entry inhibitor. It is currently being investigated as a potential microbicide for use in the prevention of the transmission of HIV.
DNA dC->dU-editing enzyme APOBEC-3C is a protein that in humans is encoded by the APOBEC3C gene.
Interferon-induced transmembrane protein 1 is a protein that in humans is encoded by the IFITM1 gene. IFITM1 has also recently been designated CD225. This protein has several additional names: fragilis, IFI17 [interferon-induced protein 17], 9-27 [Interferon-inducible protein 9-27] and Leu13.
Tetherin, also known as bone marrow stromal antigen 2, is a lipid raft associated protein that in humans is encoded by the BST2 gene. In addition, tetherin has been designated as CD317. This protein is constitutively expressed in mature B cells, plasma cells and plasmacytoid dendritic cells, and in many other cells, it is only expressed as a response to stimuli from IFN pathway.
A neutralizing antibody (NAb) is an antibody that defends a cell from a pathogen or infectious particle by neutralizing any effect it has biologically. Neutralization renders the particle no longer infectious or pathogenic. Neutralizing antibodies are part of the humoral response of the adaptive immune system against viruses, intracellular bacteria and microbial toxin. By binding specifically to surface structures (antigen) on an infectious particle, neutralizing antibodies prevent the particle from interacting with its host cells it might infect and destroy.
FGI-104 is the name of an experimental broad-spectrum antiviral drug, with activity against a range of viruses including hepatitis B, hepatitis C, HIV, Ebola virus, and Venezuelan equine encephalitis virus.
AntiViral-HyperActivation Limiting Therapeutics (AV-HALTs) are an investigational class of antiretroviral drugs used to treat Human Immunodeficiency Virus (HIV) infection. Unlike other antiretroviral agents given to reduce viral replication, AV-HALTs are single or combination drugs designed to reduce the rate of viral replication while, at the same time, also directly reducing the state of immune system hyperactivation now believed to drive the loss of CD4+ T helper cells leading to disease progression and Acquired Immunodeficiency Syndrome (AIDS).
Antiviral proteins are proteins that are induced by human or animal cells to interfere with viral replication. These proteins are isolated to inhibit the virus from replicating in a host's cells and stop it from spreading to other cells. The Pokeweed antiviral protein and the Zinc-Finger antiviral protein are two major antiviral proteins that have undergone several tests for viruses, including HIV and influenza.
In molecular biology, the CVNH domain is a conserved protein domain. It is found in the sugar-binding antiviral protein cyanovirin-N (CVN) as well as proteins from filamentous ascomycetes and in the fern Ceratopteris richardii.
In molecular biology, the jacalin-like lectin domain is a mannose-binding lectin domain with a beta-prism fold consisting of three 4-stranded beta-sheets, with an internal pseudo 3-fold symmetry. Some lectins in this group stimulate distinct T- and B-cell functions, such as Jacalin, which binds to the T-antigen and acts as an agglutinin. This domain is found in 1 to 6 copies in lectins. The domain is also found in the salt-stress induced protein from rice and an animal prostatic spermine-binding protein.
Scytovirin is a 95-amino acid antiviral protein isolated from the cyanobacteria Scytonema varium. It has been cultured in E. coli and its structure investigated in detail. Scytovirin is thought to be produced by the bacteria to protect itself from viruses that might otherwise attack it, but as it has broad-spectrum antiviral activity against a range of enveloped viruses, scytovirin has also been found to be useful against a range of major human pathogens, most notably HIV / AIDS but also including SARS coronavirus and filoviruses such as Ebola virus and Marburg virus. While some lectins such as cyanovirin and Urtica dioica agglutinin are thought likely to be too allergenic to be used internally in humans, studies so far on scytovirin and griffithsin have not shown a similar level of immunogenicity. Scytovirin and griffithsin are currently being investigated as potential microbicides for topical use.
Nonstructural protein 5A (NS5A) inhibitors are direct acting antiviral agents (DAAs) that target viral proteins, and their development was a culmination of increased understanding of the viral life cycle combined with advances in drug discovery technology. However, their mechanism of action is complex and not fully understood. NS5A inhibitors were the focus of much attention when they emerged as a part of the first curative treatment for hepatitis C virus (HCV) infections in 2014. Favorable characteristics have been introduced through varied structural changes, and structural similarities between NS5A inhibitors that are clinically approved are readily apparent. Despite the recent introduction of numerous new antiviral drugs, resistance is still a concern and these inhibitors are therefore always used in combination with other drugs.
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.
