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. Unlike most antibiotics, antiviral drugs do not destroy their target pathogen; instead they inhibit its development.
Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent. In a typical infectious disease, the incubation period signifies the period taken by the multiplying organism to reach a threshold necessary to produce symptoms in the host.
Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte critical to the innate immune system that belong to the rapidly expanding family of innate lymphoid cells (ILC) and represent 5–20% of all circulating lymphocytes in humans. The role of NK cells is analogous to that of cytotoxic T cells in the vertebrate adaptive immune response. NK cells provide rapid responses to virus-infected cell and other intracellular pathogens acting at around 3 days after infection, and respond to tumor formation. Typically, immune cells detect the major histocompatibility complex (MHC) presented on infected cell surfaces, triggering cytokine release, causing the death of the infected cell by lysis or apoptosis. NK cells are unique, however, as they have the ability to recognize and kill stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction. They were named "natural killers" because of the notion that they do not require activation to kill cells that are missing "self" markers of MHC class 1. This role is especially important because harmful cells that are missing MHC I markers cannot be detected and destroyed by other immune cells, such as T lymphocyte cells.
Original antigenic sin, also known as antigenic imprinting or the Hoskins effect, refers to the propensity of the body's immune system to preferentially utilize immunological memory based on a previous infection when a second slightly different version of that foreign pathogen is encountered. This leaves the immune system "trapped" by the first response it has made to each antigen, and unable to mount potentially more effective responses during subsequent infections. Antibodies or T-cells induced during infections with the first variant of the pathogen are subject to a form of original antigenic sin, termed repertoire freeze.
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.
Umifenovir, sold under the brand name Arbidol, is an antiviral medication for the treatment of influenza infection used in Russia and China. The drug is manufactured by Pharmstandard. Russian and China studies have shown it to be effective and it is approved in both countries while, it is not approved by the US FDA for the treatment or prevention of influenza because it was never applied for FDA approval since the drug company is in Russia not the US.
Antigenic variation or antigenic alteration refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host immune response, making it one of the mechanisms of antigenic escape. It is related to phase variation. Antigenic variation not only enables the pathogen to avoid the immune response in its current host, but also allows re-infection of previously infected hosts. Immunity to re-infection is based on recognition of the antigens carried by the pathogen, which are "remembered" by the acquired immune response. If the pathogen's dominant antigen can be altered, the pathogen can then evade the host's acquired immune system. Antigenic variation can occur by altering a variety of surface molecules including proteins and carbohydrates. Antigenic variation can result from gene conversion, site-specific DNA inversions, hypermutation, or recombination of sequence cassettes. The result is that even a clonal population of pathogens expresses a heterogeneous phenotype. Many of the proteins known to show antigenic or phase variation are related to virulence.
Antibody-dependent enhancement (ADE), sometimes less precisely called immune enhancement or disease enhancement, is a phenomenon in which binding of a virus to suboptimal antibodies enhances its entry into host cells, followed by its replication. The suboptimal antibodies can result from natural infection or from vaccination. ADE may cause enhanced respiratory disease and acute lung injury after respiratory virus infection (ERD) with symptoms of monocytic infiltration and an excess of eosinophils in respiratory tract. ADE along with type 2 T helper cell-dependent mechanisms may contribute to a development of the vaccine associated disease enhancement (VADE), which is not limited to respiratory disease. Some vaccine candidates that targeted coronaviruses, RSV virus and Dengue virus elicited VADE, and were terminated from further development or became approved for use only for patients who had those viruses before.
A virus is a tiny infectious agent that reproduces inside the cells of living hosts. When infected, the host cell is forced to rapidly produce thousands of identical copies of the original virus. Unlike most living things, viruses do not have cells that divide; new viruses assemble in the infected host cell. But unlike simpler infectious agents like prions, they contain genes, which allow them to mutate and evolve. Over 4,800 species of viruses have been described in detail out of the millions in the environment. Their origin is unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria.
HLA class I histocompatibility antigen, alpha chain F is a protein that in humans is encoded by the HLA-F gene.
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology.
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. Immunity due to neutralizing antibodies is also known as sterilizing immunity, as the immune system eliminates the infectious particle before any infection takes place.
Akiko Iwasaki is the Waldemar Von Zedtwitz Professor in the Department of Immunobiology and a Professor in the Department of Molecular, Cellular, and Developmental Biology at Yale University. She is also a principal investigator at the Howard Hughes Medical Institute. Her research interests include innate immunity, autophagy, inflammasomes, sexually transmitted infections, herpes simplex virus, human papillomavirus, respiratory virus infections, influenza infection, T cell immunity, and commensal bacteria.
Chen Hualan is a Chinese animal virologist best known for researching animal epidemic diseases. She is a member of the World Organisation for Animal Health (OIE) and a member of the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT). She is now a researcher and PhD Supervisor at Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences.
Gary J. Nabel, M.D., Ph.D, is an American virologist and immunologist, and President and Chief Executive Officer of ModeX Therapeutics in Natick, Massachusetts.
Persephone Borrow is a viral immunologist specialising in T-cell responses in acute and early HIV-1 infections. She has been at the University of Oxford since 2005 and in 2016 was made a professor there.
Edward Charles Holmes is an evolutionary biologist and virologist, and since 2012 a National Health and Medical Research Council (NHMRC) Australia Fellow and professor at the University of Sydney. He is also an Honorary Visiting Professor at Fudan University, Shanghai, China (2019–present)
Sir Andrew James McMichael, is an immunologist, Professor of Molecular Medicine, and previously Director of the Weatherall Institute of Molecular Medicine at the University of Oxford. He is particularly known for his work on T cell responses to viral infections such as influenza and HIV.
Carol Shoshkes Reiss, an American viral immunologist, has been professor in New York University's department of biology since 1991. Her research focused on the dynamic contest between the mouse immune system and virus replication during infection of the central nervous system. Reiss was editor-in-chief of the journal Viral Immunology (2000–2006) and is currently editor-in-chief of the journal DNA and Cell Biology (2012–present).
Marylyn Martina Addo is a German virologist who is a Professor and the German Center for Infection Research (DZIF) Head of Infectious Disease at the University Medical Center Hamburg-Eppendorf. Addo has developed and tested vaccinations that protect people from Ebola virus disease and the MERS coronavirus EMC/2012. She is currently developing a viral vector based COVID-19 vaccine.
