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Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms, and most cause diseases, whose respective economic importance to humans varies widely. A recent metatranscriptomics study suggests that the host diversity of viroids and other viroid-like elements is broader than previously thought and that it would not be limited to plants, encompassing even the prokaryotes.
A biosafety level (BSL), or pathogen/protection level, is a set of biocontainment precautions required to isolate dangerous biological agents in an enclosed laboratory facility. The levels of containment range from the lowest biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4). In the United States, the Centers for Disease Control and Prevention (CDC) have specified these levels in a publication referred to as BMBL. In the European Union, the same biosafety levels are defined in a directive. In Canada the four levels are known as Containment Levels. Facilities with these designations are also sometimes given as P1 through P4, as in the term P3 laboratory.
Virus classification is the process of naming viruses and placing them into a taxonomic system similar to the classification systems used for cellular organisms.
Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of progressive, incurable, and fatal conditions that are associated with prions and affect the brain and nervous system of many animals, including humans, cattle, and sheep. According to the most widespread hypothesis, they are transmitted by prions, though some other data suggest an involvement of a Spiroplasma infection. Mental and physical abilities deteriorate and many tiny holes appear in the cortex causing it to appear like a sponge when brain tissue obtained at autopsy is examined under a microscope. The disorders cause impairment of brain function which may result in memory loss, personality changes, and abnormal or impaired movement which worsen over time.
Defective interfering particles (DIPs), also known as defective interfering viruses, are spontaneously generated virus mutants in which a critical portion of the particle's genome has been lost due to defective replication or non-homologous recombination. The mechanism of their formation is presumed to be as a result of template-switching during replication of the viral genome, although non-replicative mechanisms involving direct ligation of genomic RNA fragments have also been proposed. DIPs are derived from and associated with their parent virus, and particles are classed as DIPs if they are rendered non-infectious due to at least one essential gene of the virus being lost or severely damaged as a result of the defection. A DIP can usually still penetrate host cells, but requires another fully functional virus particle to co-infect a cell with it, in order to provide the lost factors.
A satellite is a subviral agent that depends on the coinfection of a host cell with a helper virus for its replication. Satellites can be divided into two major classes: satellite viruses and satellite nucleic acids. Satellite viruses, which are most commonly associated with plants, are also found in mammals, arthropods, and bacteria. They encode structural proteins to enclose their genetic material, which are therefore distinct from the structural proteins of their helper viruses. Satellite nucleic acids, in contrast, do not encode their own structural proteins, but instead are encapsulated by proteins encoded by their helper viruses. The genomes of satellites range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV).
In botany and agriculture, stunting describes a plant disease that results in dwarfing and loss of vigor. It may be caused by infectious or noninfectious means. Stunted growth can affect foliage and crop yields, as well as eating quality in edible plants. Stunted growth can be prevented through controlling quality of seeds, soil, and proper watering practices. Treatment will vary greatly depending on the root cause of the stunting.
Nutmeg oil is a volatile essential oil from nutmeg. The oil is colorless or light yellow and smells and tastes of nutmeg. It contains numerous components of interest to the oleochemical industry. The essential oil consists of approximately 90% terpene hydrocarbons. Prominent components are sabinene, α-pinene, β-pinene, and limonene. A major oxygen-containing component is terpinen-4-ol. The oil also contains small amounts of various phenolic compounds and aromatic ethers, e.g. myristicin, elemicin, safrole, and methyl eugenol. The phenolic fraction is considered main contributor to the characteristic nutmeg odor. However, in spite of the low oil content, the characteristic composition of nutmeg oil makes it a valuable product for food, cosmetic and pharmaceutical industries. Therefore, an improved process for its extraction would be of industrial interest.
Chromatoidal bodies are aggregations of ribosomes found in cysts of some amoebae including Entamoeba histolytica and Entamoeba coli. They exist in the cytoplasm and are dark staining. In the early cystic stages of E. histolytica, chromatid bodies arise from aggregation of ribosomes forming polycrystalline masses. As the cyst matures, the masses fragment into separate particles and the chromatoidal body disappears. It is thought that the chromatoidal body formation is a manifestation of parasite-host adaptive conditions. Ribonucleoprotein is synthesized under favorable conditions, crystallized in the resistant cyst stage and dispersed in the newly excysted amoebae when the amoeba is able to establish itself in a new host.
In politics, a party secretary is a senior official within a political party with responsibility for the organizational and daily political work. In most parties, the party secretary is second in rank to the party leader. In some parties, especially the communist parties, the General Secretary is the leader.
A jute mill is a factory for processing jute. There is evidence of jute fibre extraction dating back to the Han dynasty, with a fragment of jute paper being discovered in Dunhuang, in the Gansu Province. The first known mechanical jute mills are believed to have been converted Flax mills, the oldest possibly being establish in Dundee, after a contract was agreed with the East India Company, for the supply of jute as a substitute for then scarce flax, in 1820. By the mid-1800s jute mills were being established in British India, George Acland's Mill of 1855, at Rishra, being the oldest. The world's largest jute mill was the Adamjee Jute Mills at Narayanganj in Bangladesh, which closed all operations in 2002.
Cefalotin (INN) or cephalothin (USAN) is a first-generation cephalosporin antibiotic with broad spectrum antibiotic activity. It was the first cephalosporin marketed (1964) and continues to be widely used. Cefalotin is used for bacterial infections of the respiratory tract, urinary tract, skin, soft tissues, bones and joints, sepsis, peritonitis, osteomyelitis, mastitis, infected wounds, and post-operational infections.
A glioblast is a type of cell located in the embryonic neuroectoderm that has the ability to differentiate into several different types of neuroglia through asymmetric cell division.
In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen such as a parasite or microbe, to another living organism. Agents regarded as vectors are mostly blood-sucking insects such as mosquitoes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected the stomach tissue of a mosquito.
Histaminergic means "working on the histamine system", and histaminic means "related to histamine".
Virus quantification is counting or calculating the number of virus particles (virions) in a sample to determine the virus concentration. It is used in both research and development (R&D) in academic and commercial laboratories as well as in production situations where the quantity of virus at various steps is an important variable that must be monitored. For example, the production of virus-based vaccines, recombinant proteins using viral vectors, and viral antigens all require virus quantification to continually monitor and/or modify the process in order to optimize product quality and production yields and to respond to ever changing demands and applications. Other examples of specific instances where viruses need to be quantified include clone screening, multiplicity of infection (MOI) optimization, and adaptation of methods to cell culture.
Gene transfer agents (GTAs) are DNA-containing virus-like particles that are produced by some bacteria and archaea and mediate horizontal gene transfer. Different GTA types have originated independently from viruses in several bacterial and archaeal lineages. These cells produce GTA particles containing short segments of the DNA present in the cell. After the particles are released from the producer cell, they can attach to related cells and inject their DNA into the cytoplasm. The DNA can then become part of the recipient cells' genome.
In biology, a pathogen, in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
Callyspongia truncata is a species of marine sea sponge. Like all marine sponges, C. truncata is a member of phylum Porifera and is defined by its filter-feeding lifestyle and flagellated choanocytes, or collar cells, that allow for water movement and feeding. It is a species of demosponge and a member of Demospongiae, the largest class of sponges as well as the family Callyspongiidae. C. truncata is most well known for being the organism from which the polyketide Callystatin A was identified. Callystatin A is a polyketide natural product from the leptomycin family of antibiotics. It was first isolated in 1997 from this organism, which was collected from the Goto Islands in the Nagasaki Prefecture of Japan by the Kobayashi group. Recent studies have revealed numerous other bioactive compounds that have been found in this species.
A therapeutic interfering particle is an antiviral preparation that reduces the replication rate and pathogenesis of a particular viral infectious disease. A therapeutic interfering particle is typically a biological agent (i.e., nucleic acid) engineered from portions of the viral genome being targeted. Similar to Defective Interfering Particles (DIPs), the agent competes with the pathogen within an infected cell for critical viral replication resources, reducing the viral replication rate and resulting in reduced pathogenesis. But, in contrast to DIPs, TIPs are engineered to have an in vivo basic reproductive ratio (R0) that is greater than 1 (R0>1). The term "TIP" was first introduced in 2011 based on models of its mechanism-of-action from 2003. Given their unique R0>1 mechanism of action, TIPs exhibit high barriers to the evolution of antiviral resistance and are predicted to be resistance proof. Intervention with therapeutic interfering particles can be prophylactic (to prevent or ameliorate the effects of a future infection), or a single-administration therapeutic (to fight a disease that has already occurred, such as HIV or COVID-19). Synthetic DIPs that rely on stimulating innate antiviral immune responses (i.e., interferon) were proposed for influenza in 2008 and shown to protect mice to differing extents but are technically distinct from TIPs due to their alternate molecular mechanism of action which has not been predicted to have a similarly high barrier to resistance. Subsequent work tested the pre-clinical efficacy of TIPs against HIV, a synthetic DIP for SARS-CoV-2 (in vitro), and a TIP for SARS-CoV-2 (in vivo).
References
- ↑ "Subviral Agent - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2024-02-28.
- ↑ Kogay, Roman; Koppenhöfer, Sonja; Beatty, J Thomas; Kuhn, Jens H.; Lang, Andrew S.; Zhaxybayeva, Olga (2022). "Formal recognition and classification of gene transfer agents as viriforms". Virus Evolution. 8 (2): veac100. doi:10.1093/ve/veac100. PMC 9662315 . PMID 36381234 . Retrieved 2024-02-28.
- ↑ Thompson, Joanna. "Weird 'Obelisks' Found in Human Gut May be Virus-Like Entities". Scientific American. Retrieved 2024-02-28.
- ↑ "Defective Interfering Particle - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2024-02-28.
- ↑ "ICTV". 2022-07-02. Archived from the original on 2022-07-02. Retrieved 2024-02-28.