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Circoviridae Infections
''Circoviridae'' is a family of DNA viruses. Birds and mammals serve as natural hosts. There are 101 species in this family, assigned to 2 genera. Diseases associated with this family include: PCV-2: postweaning multisystemic wasting syndrome; CAV: chicken infectious anemia. Structure Viruses in the family ''Circoviridae'' are non-enveloped, with icosahedral and round geometries, and T=1 symmetry. The diameter is around 20 nm. Genomes are circular and non-segmented, around 3.8kb in length. The capsid consists of 12 pentagonal trumpet-shaped pentamers. There are two main open reading frames arranged in opposite directions that encode the replication and capsid proteins. Alternative start codons are common in the avian species. Life cycle Viral replication is nuclear. Entry into the host cell is achieved by penetration into the host cell. Replication follows the ssDNA rolling circle model. DNA templated transcription, with some alternative splicing mechanism is the me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circovirus
''Circovirus'' is a genus of viruses, in the family ''Circoviridae''. Birds (such as pigeons and ducks) and pigs serve as natural hosts, though dogs have been shown to be infected as well. It is a single stranded DNA virus (ssDNA). There are 49 species in this genus. Some members of this genus cause disease: PCV-1 is non pathogenic, while PCV-2 causes postweaning multisystemic wasting syndrome (PMWS). Taxonomy The following species are recognized: *'' Barbel circovirus'' *'' Bat associated circovirus 1'' *'' Bat associated circovirus 2'' *'' Bat associated circovirus 3'' *'' Bat associated circovirus 4'' *'' Bat associated circovirus 5'' *'' Bat associated circovirus 6'' *'' Bat associated circovirus 7'' *'' Bat associated circovirus 8'' *'' Bat associated circovirus 9'' *'' Bat associated circovirus 10'' *'' Bat associated circovirus 11'' *'' Bat associated circovirus 12'' *'' Bat associated circovirus 13'' *'' Beak and feather disease virus'' *'' Bear circovirus'' *'' Canary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclovirus
The viral genus ''Cyclovirus'' is a genus in the family ''Circoviridae''. Viruses in this genus have been isolated from Dragonfly, dragonflies, as well as chickens, goats, sheep, and other farm animals. Cycloviruses have also been found in the feces of healthy humans and chimpanzees and in samples of cerebrospinal fluid from patients with unexplained paraplegia. Species The following species are recognized: *''Ant associated cyclovirus 1'' *''Bat associated cyclovirus 1'' *''Bat associated cyclovirus 2'' *''Bat associated cyclovirus 3'' *''Bat associated cyclovirus 4'' *''Bat associated cyclovirus 5'' *''Bat associated cyclovirus 6'' *''Bat associated cyclovirus 7'' *''Bat associated cyclovirus 8'' *''Bat associated cyclovirus 9'' *''Bat associated cyclovirus 10'' *''Bat associated cyclovirus 11'' *''Bat associated cyclovirus 12'' *''Bat associated cyclovirus 13'' *''Bat associated cyclovirus 14'' *''Bat associated cyclovirus 15'' *''Bat associated cyclovirus 16'' *''Bovine associ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Virus
A DNA virus is a virus that has a genome made of deoxyribonucleic acid (DNA) that is replicated by a DNA polymerase. They can be divided between those that have two strands of DNA in their genome, called double-stranded DNA (dsDNA) viruses, and those that have one strand of DNA in their genome, called single-stranded DNA (ssDNA) viruses. dsDNA viruses primarily belong to two realms: ''Duplodnaviria'' and ''Varidnaviria'', and ssDNA viruses are almost exclusively assigned to the realm ''Monodnaviria'', which also includes some dsDNA viruses. Additionally, many DNA viruses are unassigned to higher taxa. Reverse transcribing viruses, which have a DNA genome that is replicated through an RNA intermediate by a reverse transcriptase, are classified into the kingdom '' Pararnavirae'' in the realm '' Riboviria''. DNA viruses are ubiquitous worldwide, especially in marine environments where they form an important part of marine ecosystems, and infect both prokaryotes and eukaryotes. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postweaning Multisystemic Wasting Syndrome
Porcine circoviral disease (PCVD) and porcine circovirus associated disease (PCVAD), is a disease seen in domestic pigs. This disease causes illness in piglets, with clinical signs including progressive loss of body condition, visibly enlarged lymph nodes, difficulty in breathing, and sometimes diarrhea, pale skin, and jaundice. PCVD is very damaging to the pig-producing industry and has been reported worldwide. PCVD is caused by ''Porcine circovirus 2'' (PCV-2). The North American industry endorses "PCVAD" and European use "PCVD" to describe this disease. PMWS and PCV-2 ''Postweaning multisystemic wasting syndrome'' (''PMWS'') is the classic PCVD entity, caused by PCV-2. PCV-2 has a near universal distribution – present in most pig herds. In contrast, PMWS is more sporadic in its distribution. Experimental induction of PMWS has not been achieved by PCV-2 infection alone, using infectious DNA clones of the virus or a pure form of PCV-2 derived from infectious DNA clones. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CccDNA
cccDNA (covalently closed circular DNA) is a special DNA structure that arises during the propagation of some viruses in the cell nucleus and may remain permanently there. It is a double-stranded DNA that originates in a linear form that is ligated by means of DNA ligase to a covalently closed ring. In most cases, transcription of viral DNA can occur from the circular form only. The cccDNA of viruses is also known as episomal DNA or occasionally as a minichromosome. cccDNA was first described in bacteriophages, but it was also found in some cell cultures where an infection of DNA viruses (''Polyomaviridae'') was detected. cccDNA is typical of ''Caulimoviridae'' and ''Hepadnaviridae'', including the hepatitis B virus (HBV). cccDNA in HBV is formed by conversion of capsid-associated relaxed circular DNA (rcDNA). Following hepatitis B infections, cccDNA can remain following clinical treatment in liver cells and can rarely reactivate. The relative quantity of cccDNA present is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capsid
A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid. Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Reading Frame
In molecular biology, open reading frames (ORFs) are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames will be "open" (the "reading", however, refers to the RNA produced by transcription of the DNA and its subsequent interaction with the ribosome in translation). Such an ORF may contain a start codon (usually AUG in terms of RNA) and by definition cannot extend beyond a stop codon (usually UAA, UAG or UGA in RNA). That start codon (not necessarily the first) indicates where translation may start. The transcription termination site is located after the ORF, beyond the translation stop codon. If transcription were to cease before the stop codon, an incomplete protein would be made during translation. In eukaryotic genes with multiple exons, introns are removed and exons are then joined together after transcription to yield the final ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codon
The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets, or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries. The codons specify which amino acid will be added next during protein biosynthesis. With some exceptions, a three-nucleotide codon in a nucleic acid sequence specifies a single amino acid. The vast majority of genes are encoded with a single scheme (see the RNA codon table). That scheme is often referred to as the canonical or standard genetic code, or simply ''the'' genetic code, though variant codes (such as in mitochondria) exist. History Efforts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porcine Circovirus
Porcine circovirus (PCV) is a group of four single-stranded DNA viruses that are non-enveloped with an unsegmented circular genome. They are members of the genus '' Circovirus'' that can infect pigs. The viral capsid is icosahedral and approximately 17 nm in diameter. PCVs are the smallest viruses replicating autonomously in eukaryotic cells. They replicate in the nucleus of infected cells, using the host polymerase for genome amplification. PCV-2 causes Porcine circovirus associated disease or postweaning multisystemic wasting syndrome (PMWS). An effective vaccination is now available. Fort Dodge Animal Health (Wyeth) launched the first USDA approved vaccine in 2006, containing an inactivated virus (ATCvet code: ). Classification Three strains of PCV are known as of 2018: * PCV-1 (first identified in 1974) readily infects, but is not known to cause disease in swine. * PCV-2 (first isolated in 1997) causes PMWS, which over time results in significant depletion of ly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Associated Cyclovirus 8
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, and language. Humans are highly social and tend to live in complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established a wide variety of values, social norms, and rituals, which bolster human society. Its intelligence and its desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of study. Although some scientists equate the term ''humans'' with all members of the genus ''Homo'', in common usage, it generally refers to ''Homo sapiens'', the only extant member. Anatomically modern huma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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