Plant Viruses: Viruses parasitic on plants higher than bacteria.Plants, Genetically Modified: PLANTS, or their progeny, whose GENOME has been altered by GENETIC ENGINEERING.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)RNA Viruses: Viruses whose genetic material is RNA.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Tobacco: A plant genus of the family SOLANACEAE. Members contain NICOTINE and other biologically active chemicals; its dried leaves are used for SMOKING.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Genes, Plant: The functional hereditary units of PLANTS.Plants, Toxic: Plants or plant parts which are harmful to man or other animals.Plant Diseases: Diseases of plants.Potexvirus: A genus of plant viruses in the family FLEXIVIRIDAE, that cause mosaic and ringspot symptoms. Transmission occurs mechanically. Potato virus X is the type species.Mosaic Viruses: Viruses which produce a mottled appearance of the leaves of plants.Tobacco Mosaic Virus: The type species of TOBAMOVIRUS which causes mosaic disease of tobacco. Transmission occurs by mechanical inoculation.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Comovirus: A genus of plant viruses of the family COMOVIRIDAE in which the bipartite genome is encapsidated in separate icosahedral particles. Mosaic and mottle symptoms are characteristic, and transmission is exclusively by leaf-feeding beetles. Cowpea mosaic virus is the type species.Plant Shoots: New immature growth of a plant including stem, leaves, tips of branches, and SEEDLINGS.RNA, Viral: Ribonucleic acid that makes up the genetic material of viruses.Virus Replication: The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle.Vaccinia virus: The type species of ORTHOPOXVIRUS, related to COWPOX VIRUS, but whose true origin is unknown. It has been used as a live vaccine against SMALLPOX. It is also used as a vector for inserting foreign DNA into animals. Rabbitpox virus is a subspecies of VACCINIA VIRUS.Hemiptera: A large order of insects characterized by having the mouth parts adapted to piercing or sucking. It is comprised of four suborders: HETEROPTERA, Auchenorrhyncha, Sternorrhyncha, and Coleorrhyncha.Plant Viral Movement Proteins: Viral proteins that facilitate the movement of viruses between plant cells by means of PLASMODESMATA, channels that traverse the plant cell walls.Plants, Medicinal: Plants whose roots, leaves, seeds, bark, or other constituent parts possess therapeutic, tonic, purgative, curative or other pharmacologic attributes, when administered to man or animals.Viral Proteins: Proteins found in any species of virus.Tombusviridae: A family of RNA plant viruses infecting dicotyledons. Transmission is mainly by mechanical inoculation and through propagative plant material. All species elicit formation of multivesicular inclusion bodies. There are at least eight genera: Aureusvirus, Avenavirus, CARMOVIRUS, Dianthovirus, Machlomovirus, Necrovirus, Panicovirus, and TOMBUSVIRUS.DNA, Plant: Deoxyribonucleic acid that makes up the genetic material of plants.Potyviridae: A family of RNA plant viruses with flexuous, filamentous particles and consisting of six genera: POTYVIRUS; Ipomovirus; Macluravirus; Rymovirus; Tritimovirus; and Bymovirus. All members of the family form cytoplasmic cylindrical inclusion bodies during infection.Aphids: A family (Aphididae) of small insects, in the suborder Sternorrhyncha, that suck the juices of plants. Important genera include Schizaphis and Myzus. The latter is known to carry more than 100 virus diseases between plants.DNA Viruses: Viruses whose nucleic acid is DNA.Plant Development: Processes orchestrated or driven by a plethora of genes, plant hormones, and inherent biological timing mechanisms facilitated by secondary molecules, which result in the systematic transformation of plants and plant parts, from one stage of maturity to another.Potyvirus: A large genus of plant viruses of the family POTYVIRIDAE which infect mainly plants of the Solanaceae. Transmission is primarily by aphids in a non-persistent manner. The type species is potato virus Y.Flexiviridae: A family of RNA plant viruses that infect a wide range of herbaceous and woody plant species. There are at least eight genera including POTEXVIRUS and CARLAVIRUS, both of which are highly immunogenic.Receptors, Virus: Specific molecular components of the cell capable of recognizing and interacting with a virus, and which, after binding it, are capable of generating some signal that initiates the chain of events leading to the biological response.Virus Cultivation: Process of growing viruses in live animals, plants, or cultured cells.Virus Assembly: The assembly of VIRAL STRUCTURAL PROTEINS and nucleic acid (VIRAL DNA or VIRAL RNA) to form a VIRUS PARTICLE.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Virus Shedding: The expelling of virus particles from the body. Important routes include the respiratory tract, genital tract, and intestinal tract. Virus shedding is an important means of vertical transmission (INFECTIOUS DISEASE TRANSMISSION, VERTICAL).Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Plant Cells: Basic functional unit of plants.Virus Diseases: A general term for diseases produced by viruses.Simian virus 40: A species of POLYOMAVIRUS originally isolated from Rhesus monkey kidney tissue. It produces malignancy in human and newborn hamster kidney cell cultures.Capsid: The outer protein protective shell of a virus, which protects the viral nucleic acid.Genes, Viral: The functional hereditary units of VIRUSES.Capsid Proteins: Proteins that form the CAPSID of VIRUSES.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Defective Viruses: Viruses which lack a complete genome so that they cannot completely replicate or cannot form a protein coat. Some are host-dependent defectives, meaning they can replicate only in cell systems which provide the particular genetic function which they lack. Others, called SATELLITE VIRUSES, are able to replicate only when their genetic defect is complemented by a helper virus.Tospovirus: A genus of plant viruses in the family BUNYAVIRIDAE. Tomato spotted wilt virus is the type species. Transmission occurs by at least nine species of thrips.Sindbis Virus: The type species of ALPHAVIRUS normally transmitted to birds by CULEX mosquitoes in Egypt, South Africa, India, Malaya, the Philippines, and Australia. It may be associated with fever in humans. Serotypes (differing by less than 17% in nucleotide sequence) include Babanki, Kyzylagach, and Ockelbo viruses.Cucumovirus: A genus of plant viruses of the family BROMOVIRIDAE, which infect cucurbits and solanaceous plants. Transmission occurs via aphids in a non-persistent manner, and also via seeds. The type species Cucumber mosaic virus, a CUCUMOVIRUS, should not be confused with Cucumber green mottle mosaic virus, a TOBAMOVIRUS.Measles virus: The type species of MORBILLIVIRUS and the cause of the highly infectious human disease MEASLES, which affects mostly children.Host-Pathogen Interactions: The interactions between a host and a pathogen, usually resulting in disease.Luteovirus: A genus of plant viruses that infects both monocotyledonous and dicotyledonous plants. Its organisms are persistently transmitted by aphids, and weeds may provide reservoirs of infection.Plasmodesmata: Membrane-like channels of cytoplasm connecting adjacent plant cells. Plasmodesmata connect through pores in the CELL WALL and associate with the CYTOSKELETON machinery. They are essential for intercellular transport and communication.Influenza A Virus, H1N1 Subtype: A subtype of INFLUENZA A VIRUS with the surface proteins hemagglutinin 1 and neuraminidase 1. The H1N1 subtype was responsible for the Spanish flu pandemic of 1918.Genome, Plant: The genetic complement of a plant (PLANTS) as represented in its DNA.Caulimovirus: A genus of PLANT VIRUSES, in the family CAULIMOVIRIDAE, that are transmitted by APHIDS in a semipersistent manner. Aphid-borne transmission of some caulimoviruses requires certain virus-coded proteins termed transmission factors.Rabies virus: The type species of LYSSAVIRUS causing rabies in humans and other animals. Transmission is mostly by animal bites through saliva. The virus is neurotropic multiplying in neurons and myotubes of vertebrates.Influenza A Virus, H5N1 Subtype: A subtype of INFLUENZA A VIRUS comprised of the surface proteins hemagglutinin 5 and neuraminidase 1. The H5N1 subtype, frequently referred to as the bird flu virus, is endemic in wild birds and very contagious among both domestic (POULTRY) and wild birds. It does not usually infect humans, but some cases have been reported.Lycopersicon esculentum: A plant species of the family SOLANACEAE, native of South America, widely cultivated for their edible, fleshy, usually red fruit.Begomovirus: A genus of plant viruses in the family GEMINIVIRIDAE that are transmitted in nature by whitefly Bemisia tabaci.Tombusvirus: A genus of plant viruses that infects ANGIOSPERMS. Transmission occurs mechanically and through soil, with one species transmitted via a fungal vector. The type species is Tomato bushy stunt virus.Luteoviridae: A family of RNA plant viruses infecting disparate plant families. They are transmitted by specific aphid vectors. There are three genera: LUTEOVIRUS; Polerovirus; and Enamovirus.Nepovirus: A genus of polyhedral plant viruses of the family COMOVIRIDAE causing ringspots and spotting on leaves or sometimes symptomless infection. Transmission occurs by seeds, soil nematodes, or experimentally by mechanical inoculation. Tobacco ringspot virus is the type species.Plants, Edible: An organism of the vegetable kingdom suitable by nature for use as a food, especially by human beings. Not all parts of any given plant are edible but all parts of edible plants have been known to figure as raw or cooked food: leaves, roots, tubers, stems, seeds, buds, fruits, and flowers. The most commonly edible parts of plants are FRUIT, usually sweet, fleshy, and succulent. Most edible plants are commonly cultivated for their nutritional value and are referred to as VEGETABLES.Tobamovirus: A genus of plant viruses in which the virion is a rigid filament. Transmission is by mechanical inoculation or seed. The type species is TOBACCO MOSAIC VIRUS.Closterovirus: A genus of plant viruses in the family CLOSTEROVIRIDAE containing highly flexuous filaments. Some members are important pathogens of crop plants. Natural vectors include APHIDS, whiteflies, and mealybugs. The type species is Beet yellows virus.Gene Expression Regulation, Viral: Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.Virion: The infective system of a virus, composed of the viral genome, a protein core, and a protein coat called a capsid, which may be naked or enclosed in a lipoprotein envelope called the peplos.Plant Structures: The parts of plants, including SEEDS.Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.Influenza A Virus, H3N2 Subtype: A subtype of INFLUENZA A VIRUS comprised of the surface proteins hemagglutinin 3 and neuraminidase 2. The H3N2 subtype was responsible for the Hong Kong flu pandemic of 1968.Hepatitis B virus: The type species of the genus ORTHOHEPADNAVIRUS which causes human HEPATITIS B and is also apparently a causal agent in human HEPATOCELLULAR CARCINOMA. The Dane particle is an intact hepatitis virion, named after its discoverer. Non-infectious spherical and tubular particles are also seen in the serum.Geminiviridae: A family of plant viruses where the VIRION possesses an unusual morphology consisting of a pair of isometric particles. Transmission occurs via leafhoppers or whitefly. Some viruses cause economically important diseases in cultivated plants. There are four genera: Mastrevirus, Curtovirus, Topocuvirus, and BEGOMOVIRUS.Ilarvirus: A genus of the family BROMOVIRIDAE which infects mainly woody plants. Species are divided into ten subgroups. Tobacco streak virus is the type species.Arabidopsis Proteins: Proteins that originate from plants species belonging to the genus ARABIDOPSIS. The most intensely studied species of Arabidopsis, Arabidopsis thaliana, is commonly used in laboratory experiments.West Nile virus: A species of FLAVIVIRUS, one of the Japanese encephalitis virus group (ENCEPHALITIS VIRUSES, JAPANESE). It can infect birds and mammals. In humans, it is seen most frequently in Africa, Asia, and Europe presenting as a silent infection or undifferentiated fever (WEST NILE FEVER). The virus appeared in North America for the first time in 1999. It is transmitted mainly by CULEX spp mosquitoes which feed primarily on birds, but it can also be carried by the Asian Tiger mosquito, AEDES albopictus, which feeds mainly on mammals.Genome, Viral: The complete genetic complement contained in a DNA or RNA molecule in a virus.Carmovirus: A genus in the family TOMBUSVIRIDAE mostly found in temperate regions. Some species infecting legumes (FABACEAE) are reported from tropical areas. Most viruses are soil-borne, but some are transmitted by the fungus Olpidium radicale and others by beetles. Carnation mottle virus is the type species.Respiratory Syncytial Viruses: A group of viruses in the PNEUMOVIRUS genus causing respiratory infections in various mammals. Humans and cattle are most affected but infections in goats and sheep have also been reported.Satellite Viruses: Defective viruses which can multiply only by association with a helper virus which complements the defective gene. Satellite viruses may be associated with certain plant viruses, animal viruses, or bacteriophages. They differ from satellite RNA; (RNA, SATELLITE) in that satellite viruses encode their own coat protein.Plant Growth Regulators: Any of the hormones produced naturally in plants and active in controlling growth and other functions. There are three primary classes: auxins, cytokinins, and gibberellins.RNA Replicase: An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (Enzyme Nomenclature, 1992, p293)DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.Plum Pox Virus: A species of the genus POTYVIRUS that affects many species of Prunus. It is transmitted by aphids and by infected rootstocks.Cucumis sativus: A creeping annual plant species of the CUCURBITACEAE family. It has a rough succulent, trailing stem and hairy leaves with three to five pointed lobes.Virus Activation: The mechanism by which latent viruses, such as genetically transmitted tumor viruses (PROVIRUSES) or PROPHAGES of lysogenic bacteria, are induced to replicate and then released as infectious viruses. It may be effected by various endogenous and exogenous stimuli, including B-cell LIPOPOLYSACCHARIDES, glucocorticoid hormones, halogenated pyrimidines, IONIZING RADIATION, ultraviolet light, and superinfecting viruses.Insect Vectors: Insects that transmit infective organisms from one host to another or from an inanimate reservoir to an animate host.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.Protoplasts: The protoplasm and plasma membrane of plant, fungal, bacterial or archaeon cells without the CELL WALL.Vesicular stomatitis Indiana virus: The type species of VESICULOVIRUS causing a disease symptomatically similar to FOOT-AND-MOUTH DISEASE in cattle, horses, and pigs. It may be transmitted to other species including humans, where it causes influenza-like symptoms.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Open Reading Frames: A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).Genetic Vectors: DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.Virus Latency: The ability of a pathogenic virus to lie dormant within a cell (latent infection). In eukaryotes, subsequent activation and viral replication is thought to be caused by extracellular stimulation of cellular transcription factors. Latency in bacteriophage is maintained by the expression of virally encoded repressors.Chenopodium quinoa: A species of the Chenopodium genus which is the source of edible seed called quinoa. It contains makisterone A and other STEROIDS, some having ECDYSTEROID activity on insects.Hemagglutinin Glycoproteins, Influenza Virus: Membrane glycoproteins from influenza viruses which are involved in hemagglutination, virus attachment, and envelope fusion. Fourteen distinct subtypes of HA glycoproteins and nine of NA glycoproteins have been identified from INFLUENZA A VIRUS; no subtypes have been identified for Influenza B or Influenza C viruses.Plant Immunity: The inherent or induced capacity of plants to withstand or ward off biological attack by pathogens.Viral Structural Proteins: Viral proteins that are components of the mature assembled VIRUS PARTICLES. They may include nucleocapsid core proteins (gag proteins), enzymes packaged within the virus particle (pol proteins), and membrane components (env proteins). These do not include the proteins encoded in the VIRAL GENOME that are produced in infected cells but which are not packaged in the mature virus particle,i.e. the so called non-structural proteins (VIRAL NONSTRUCTURAL PROTEINS).Oncogenic Viruses: Viruses that produce tumors.Alfalfa mosaic virus: The type species of the genus ALFAMOVIRUS that is non-persistently transmitted by aphids.Vero Cells: A CELL LINE derived from the kidney of the African green (vervet) monkey, (CERCOPITHECUS AETHIOPS) used primarily in virus replication studies and plaque assays.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Simian immunodeficiency virus: Species of the genus LENTIVIRUS, subgenus primate immunodeficiency viruses (IMMUNODEFICIENCY VIRUSES, PRIMATE), that induces acquired immunodeficiency syndrome in monkeys and apes (SAIDS). The genetic organization of SIV is virtually identical to HIV.Nanovirus: A genus in the family NANOVIRIDAE containing multiple circular single-stranded DNA molecules. The type species is Subterranean clover stunt virus.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Crinivirus: A genus of plant viruses in the family CLOSTEROVIRIDAE. Transmission is by whiteflies. Lettuce infectious yellows virus is the type species.Cercopithecus aethiops: A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey (C. pygerythrus) is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.Mumps virus: The type species of RUBULAVIRUS that causes an acute infectious disease in humans, affecting mainly children. Transmission occurs by droplet infection.Parainfluenza Virus 1, Human: A species of RESPIROVIRUS also called hemadsorption virus 2 (HA2), which causes laryngotracheitis in humans, especially children.Recombination, Genetic: Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.Cucurbita: A plant genus of the family CUCURBITACEAE, order Violales, subclass Dilleniidae, which includes pumpkin, gourd and squash.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Hepatitis A virus: A species in the genus HEPATOVIRUS containing one serotype and two strains: HUMAN HEPATITIS A VIRUS and Simian hepatitis A virus causing hepatitis in humans (HEPATITIS A) and primates, respectively.Bromovirus: A genus of tripartite plant viruses in the family BROMOVIRIDAE. Transmission is by beetles. Brome mosaic virus is the type species.Semliki forest virus: A species of ALPHAVIRUS isolated in central, eastern, and southern Africa.Disease Resistance: The capacity of an organism to defend itself against pathological processes or the agents of those processes. This most often involves innate immunity whereby the organism responds to pathogens in a generic way. The term disease resistance is used most frequently when referring to plants.Tymovirus: A genus of plant viruses, in the family TYMOVIRIDAE, possessing a narrow host range that includes CRUCIFERAE. Transmission occurs by BEETLES and mechanical inoculation.Capsicum: A plant genus of the family SOLANACEAE. The hot peppers yield CAPSAICIN, which activates VANILLOID RECEPTORS. Several varieties have sweet or pungent edible fruits that are used as vegetables when fresh and spices when the pods are dried.RNA Interference: A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Antiviral Agents: Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.Plant Epidermis: A thin layer of cells forming the outer integument of seed plants and ferns. (Random House Unabridged Dictionary, 2d ed)Avian Sarcoma Viruses: Group of alpharetroviruses (ALPHARETROVIRUS) producing sarcomata and other tumors in chickens and other fowl and also in pigeons, ducks, and RATS.Neutralization Tests: The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).Virus Attachment: The binding of virus particles to receptors on the host cell surface. For enveloped viruses, the virion ligand is usually a surface glycoprotein as is the cellular receptor. For non-enveloped viruses, the virus CAPSID serves as the ligand.Viral Plaque Assay: Method for measuring viral infectivity and multiplication in CULTURED CELLS. Clear lysed areas or plaques develop as the VIRAL PARTICLES are released from the infected cells during incubation. With some VIRUSES, the cells are killed by a cytopathic effect; with others, the infected cells are not killed but can be detected by their hemadsorptive ability. Sometimes the plaque cells contain VIRAL ANTIGENS which can be measured by IMMUNOFLUORESCENCE.BK Virus: A species of POLYOMAVIRUS apparently infecting over 90% of children but not clearly associated with any clinical illness in childhood. The virus remains latent in the body throughout life and can be reactivated under certain circumstances.Fabaceae: The large family of plants characterized by pods. Some are edible and some cause LATHYRISM or FAVISM and other forms of poisoning. Other species yield useful materials like gums from ACACIA and various LECTINS like PHYTOHEMAGGLUTININS from PHASEOLUS. Many of them harbor NITROGEN FIXATION bacteria on their roots. Many but not all species of "beans" belong to this family.Genetic Variation: Genotypic differences observed among individuals in a population.Tumor Virus Infections: Infections produced by oncogenic viruses. The infections caused by DNA viruses are less numerous but more diverse than those caused by the RNA oncogenic viruses.Viruses, Unclassified: Viruses whose taxonomic relationships have not been established.JC Virus: A species of POLYOMAVIRUS, originally isolated from the brain of a patient with progressive multifocal leukoencephalopathy. The patient's initials J.C. gave the virus its name. Infection is not accompanied by any apparent illness but serious demyelinating disease can appear later, probably following reactivation of latent virus.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Solanum tuberosum: A plant species of the genus SOLANUM, family SOLANACEAE. The starchy roots are used as food. SOLANINE is found in green parts.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Avian leukosis virus: The type species of ALPHARETROVIRUS producing latent or manifest lymphoid leukosis in fowl.RNA, Double-Stranded: RNA consisting of two strands as opposed to the more prevalent single-stranded RNA. Most of the double-stranded segments are formed from transcription of DNA by intramolecular base-pairing of inverted complementary sequences separated by a single-stranded loop. Some double-stranded segments of RNA are normal in all organisms.Orthomyxoviridae: A family of RNA viruses causing INFLUENZA and other diseases. There are five recognized genera: INFLUENZAVIRUS A; INFLUENZAVIRUS B; INFLUENZAVIRUS C; ISAVIRUS; and THOGOTOVIRUS.Bluetongue virus: The type species of ORBIVIRUS causing a serious disease in sheep, especially lambs. It may also infect wild ruminants and other domestic animals.Plant Stomata: Closable openings in the epidermis of plants on the underside of leaves. They allow the exchange of gases between the internal tissues of the plant and the outside atmosphere.Orthomyxoviridae Infections: Virus diseases caused by the ORTHOMYXOVIRIDAE.Gene Silencing: Interruption or suppression of the expression of a gene at transcriptional or translational levels.Angiosperms: Members of the group of vascular plants which bear flowers. They are differentiated from GYMNOSPERMS by their production of seeds within a closed chamber (OVARY, PLANT). The Angiosperms division is composed of two classes, the monocotyledons (Liliopsida) and dicotyledons (Magnoliopsida). Angiosperms represent approximately 80% of all known living plants.Sendai virus: The type species of RESPIROVIRUS in the subfamily PARAMYXOVIRINAE. It is the murine version of HUMAN PARAINFLUENZA VIRUS 1, distinguished by host range.Moloney murine leukemia virus: A strain of Murine leukemia virus (LEUKEMIA VIRUS, MURINE) arising during the propagation of S37 mouse sarcoma, and causing lymphoid leukemia in mice. It also infects rats and newborn hamsters. It is apparently transmitted to embryos in utero and to newborns through mother's milk.Virus Integration: Insertion of viral DNA into host-cell DNA. This includes integration of phage DNA into bacterial DNA; (LYSOGENY); to form a PROPHAGE or integration of retroviral DNA into cellular DNA to form a PROVIRUS.Nucleic Acid Conformation: The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.Transcription, Genetic: The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.Sequence Homology: The degree of similarity between sequences. Studies of AMINO ACID SEQUENCE HOMOLOGY and NUCLEIC ACID SEQUENCE HOMOLOGY provide useful information about the genetic relatedness of genes, gene products, and species.Yellow fever virus: The type species of the FLAVIVIRUS genus. Principal vector transmission to humans is by AEDES spp. mosquitoes.Simplexvirus: A genus of the family HERPESVIRIDAE, subfamily ALPHAHERPESVIRINAE, consisting of herpes simplex-like viruses. The type species is HERPESVIRUS 1, HUMAN.Virulence: The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.Prunus: A plant genus in the family ROSACEAE, order Rosales, subclass Rosidae. It is best known as a source of edible fruits such as apricot, plum, peach, cherry, and almond.Brassica napus: A plant species of the family BRASSICACEAE best known for the edible roots.Hibiscus: A plant genus of the family MALVACEAE. Members contain CITRIC ACID; MALATES; ANTHOCYANINS; FLAVONOIDS; GLYCOSIDES; DIETARY FIBER; and LIGNANS. Hibiscus sabdariffa is common constituent of HERBAL TEAS. Hibiscus cannabinus is a source of hemp fiber for TEXTILES.Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Sequence Homology, Nucleic Acid: The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Respiratory Syncytial Virus Infections: Pneumovirus infections caused by the RESPIRATORY SYNCYTIAL VIRUSES. Humans and cattle are most affected but infections in goats and sheep have been reported.Virus Inactivation: Inactivation of viruses by non-immune related techniques. They include extremes of pH, HEAT treatment, ultraviolet radiation, IONIZING RADIATION; DESICCATION; ANTISEPTICS; DISINFECTANTS; organic solvents, and DETERGENTS.Myxoma virus: The type species of LEPORIPOXVIRUS causing infectious myxomatosis, a severe generalized disease, in rabbits. Tumors are not always present.Cytopathogenic Effect, Viral: Visible morphologic changes in cells infected with viruses. It includes shutdown of cellular RNA and protein synthesis, cell fusion, release of lysosomal enzymes, changes in cell membrane permeability, diffuse changes in intracellular structures, presence of viral inclusion bodies, and chromosomal aberrations. It excludes malignant transformation, which is CELL TRANSFORMATION, VIRAL. Viral cytopathogenic effects provide a valuable method for identifying and classifying the infecting viruses.Cowpox virus: A species of ORTHOPOXVIRUS that is the etiologic agent of COWPOX. It is closely related to but antigenically different from VACCINIA VIRUS.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Genetic Engineering: Directed modification of the gene complement of a living organism by such techniques as altering the DNA, substituting genetic material by means of a virus, transplanting whole nuclei, transplanting cell hybrids, etc.Variola virus: A species of ORTHOPOXVIRUS causing infections in humans. No infections have been reported since 1977 and the virus is now believed to be virtually extinct.Respiratory Syncytial Virus, Human: The type species of PNEUMOVIRUS and an important cause of lower respiratory disease in infants and young children. It frequently presents with bronchitis and bronchopneumonia and is further characterized by fever, cough, dyspnea, wheezing, and pallor.Lassa virus: A species of ARENAVIRUS, part of the Old World Arenaviruses (ARENAVIRUSES, OLD WORLD), and the etiologic agent of LASSA FEVER. LASSA VIRUS is a common infective agent in humans in West Africa. Its natural host is the multimammate mouse Mastomys natalensis.Norwalk virus: The type species in the genus NOROVIRUS, first isolated in 1968 from the stools of school children in Norwalk, Ohio, who were suffering from GASTROENTERITIS. The virions are non-enveloped spherical particles containing a single protein. Multiple strains are named after the places where outbreaks have occurred.Chikungunya virus: A species of ALPHAVIRUS causing an acute dengue-like fever.Seeds: The encapsulated embryos of flowering plants. They are used as is or for animal feed because of the high content of concentrated nutrients like starches, proteins, and fats. Rapeseed, cottonseed, and sunflower seed are also produced for the oils (fats) they yield.Influenza, Human: An acute viral infection in humans involving the respiratory tract. It is marked by inflammation of the NASAL MUCOSA; the PHARYNX; and conjunctiva, and by headache and severe, often generalized, myalgia.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Encephalitis Viruses: A collection of single-stranded RNA viruses scattered across the Bunyaviridae, Flaviviridae, and Togaviridae families whose common property is the ability to induce encephalitic conditions in infected hosts.Virus Physiological Phenomena: Biological properties, processes, and activities of VIRUSES.DNA Virus InfectionsHerpesvirus 1, Human: The type species of SIMPLEXVIRUS causing most forms of non-genital herpes simplex in humans. Primary infection occurs mainly in infants and young children and then the virus becomes latent in the dorsal root ganglion. It then is periodically reactivated throughout life causing mostly benign conditions.Vaccines, Synthetic: Small synthetic peptides that mimic surface antigens of pathogens and are immunogenic, or vaccines manufactured with the aid of recombinant DNA techniques. The latter vaccines may also be whole viruses whose nucleic acids have been modified.Epstein-Barr Virus Infections: Infection with human herpesvirus 4 (HERPESVIRUS 4, HUMAN); which may facilitate the development of various lymphoproliferative disorders. These include BURKITT LYMPHOMA (African type), INFECTIOUS MONONUCLEOSIS, and oral hairy leukoplakia (LEUKOPLAKIA, HAIRY).Plant Poisoning: Poisoning by the ingestion of plants or its leaves, berries, roots or stalks. The manifestations in both humans and animals vary in severity from mild to life threatening. In animals, especially domestic animals, it is usually the result of ingesting moldy or fermented forage.Hepacivirus: A genus of FLAVIVIRIDAE causing parenterally-transmitted HEPATITIS C which is associated with transfusions and drug abuse. Hepatitis C virus is the type species.Triticum: A plant genus of the family POACEAE that is the source of EDIBLE GRAIN. A hybrid with rye (SECALE CEREALE) is called TRITICALE. The seed is ground into FLOUR and used to make BREAD, and is the source of WHEAT GERM AGGLUTININS.Herpesvirus 4, Human: The type species of LYMPHOCRYPTOVIRUS, subfamily GAMMAHERPESVIRINAE, infecting B-cells in humans. It is thought to be the causative agent of INFECTIOUS MONONUCLEOSIS and is strongly associated with oral hairy leukoplakia (LEUKOPLAKIA, HAIRY;), BURKITT LYMPHOMA; and other malignancies.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Encephalitis Viruses, Tick-Borne: A subgroup of the genus FLAVIVIRUS that causes encephalitis and hemorrhagic fevers and is found in eastern and western Europe and the former Soviet Union. It is transmitted by TICKS and there is an associated milk-borne transmission from viremic cattle, goats, and sheep.Parainfluenza Virus 3, Human: A species of RESPIROVIRUS frequently isolated from small children with pharyngitis, bronchitis, and pneumonia.Leukemia Virus, Feline: A species of GAMMARETROVIRUS causing leukemia, lymphosarcoma, immune deficiency, or other degenerative diseases in cats. Several cellular oncogenes confer on FeLV the ability to induce sarcomas (see also SARCOMA VIRUSES, FELINE).Hordeum: A plant genus of the family POACEAE. The EDIBLE GRAIN, barley, is widely used as food.Plant Transpiration: The loss of water vapor by plants to the atmosphere. It occurs mainly from the leaves through pores (stomata) whose primary function is gas exchange. The water is replaced by a continuous column of water moving upwards from the roots within the xylem vessels. (Concise Dictionary of Biology, 1990)HIV Infections: Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Foot-and-Mouth Disease Virus: The type species of APHTHOVIRUS, causing FOOT-AND-MOUTH DISEASE in cloven-hoofed animals. Several different serotypes exist.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Flowers: The reproductive organs of plants.Hemagglutinins, Viral: Specific hemagglutinin subtypes encoded by VIRUSES.Porcine respiratory and reproductive syndrome virus: A species of ARTERIVIRUS causing reproductive and respiratory disease in pigs. The European strain is called Lelystad virus. Airborne transmission is common.