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Pseudodiploid (also called "pseudoploid") refers to one of the essential components in viral reproduction. It means having two RNA genomes per virion but giving rise to only one DNA copy in infected cells.
The term is also used to refer to cells that are diploid, but have chromosomal translocations. [1]
Retrovirions for example are considered as pseudoploid in character - they have two genomes encapsidated, but in general only one provirus is seen after infection with single virions.
Retrovirus particles contain two copies of the RNA genome held together by multiple regions of base pairing (strongest pairing at 5’ ends) which is also called 70S complex (dimer of 35S genomes). This property gives viruses evolutionary advantages such as the capability to survive extensive damage to their genomes as at least parts of both genomes are used during the reverse transcription process. It also explains the high rates of genetic recombination in retroviruses. The retroviral genome is coated by a viral nucleocapsid (NC) protein that may function like a single stranded binding protein and therefore is enhancing processivity and facilitating template exchanges. The NC first organizes RNA genomes within the virion and then facilitates reverse transcription within the infected cell.
In genetics, complementary DNA (cDNA) is DNA synthesized from a single-stranded RNA template in a reaction catalyzed by the enzyme reverse transcriptase. cDNA is often used to clone eukaryotic genes in prokaryotes. When scientists want to express a specific protein in a cell that does not normally express that protein, they will transfer the cDNA that codes for the protein to the recipient cell. cDNA is also produced naturally by retroviruses and then integrated into the host's genome, where it creates a provirus.
A retrovirus is a type of RNA virus that inserts a copy of its genome into the DNA of a host cell that it invades, thus changing the genome of that cell.
A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by retroviruses to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes, and by some non-retroviruses such as the hepatitis B virus, a member of the Hepadnaviridae, which are dsDNA-RT viruses.
Paramyxoviridae is a family of negative-sense, single-stranded RNA viruses in the order Mononegavirales. Vertebrates serve as natural hosts; no known plants serve as vectors. Currently, Paramyxoviridae has four subfamilies, 14 genera, and 72 species, three species of which are unassigned to any other clades. Diseases associated with this family include measles, mumps, and respiratory tract infections.
Hepadnaviridae is a family of viruses. Humans, apes, and birds serve as natural hosts. There are currently over 12 species in this family, divided among 5 genera. Its best-known member is hepatitis B virus. Diseases associated with this family include: liver infections, such as hepatitis, hepatocellular carcinomas, and cirrhosis.
Cauliflower mosaic virus (CaMV) is a member of the genus Caulimovirus, one of the six genera in the family Caulimoviridae, which are pararetroviruses that infect plants. Pararetroviruses replicate through reverse transcription just like retroviruses, but the viral particles contain DNA instead of RNA.
Transduction is the process by which foreign DNA is introduced into a bacterial cell by a virus or viral vector. An example is the viral transfer of DNA from one bacterium to another and hence an example of horizontal gene transfer. Transduction does not require physical contact between the cell donating the DNA and the cell receiving the DNA, and it is DNase resistant. Transduction is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome.
The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. The lytic cycle results in the destruction of the infected cell and its membrane. Bacteriophages that only use the lytic cycle are called virulent phages.
Parvovirus is the common name applied to all the viruses in the Parvoviridae taxonomic family. Parvovirus can also be used specifically for members of one of the two Parvoviridae subfamilies: Parvovirinae, which infect vertebrate hosts, and Densovirinae, which infect invertebrate hosts, are more commonly referred to as densoviruses. In subfamily Parvovirinae there are eight genera, containing a total of 58 recognized species, while in subfamily Densovirinae there are 5 genera and a total of 21 species.
Viral replication is the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. Through the generation of abundant copies of its genome and packaging these copies, the virus continues infecting new hosts. Replication between viruses is greatly varied and depends on the type of genes involved in them. Most DNA viruses assemble in the nucleus while most RNA viruses develop solely in cytoplasm.
Lentivirus is a genus of retroviruses that cause chronic and deadly diseases characterized by long incubation periods, in the human and other mammalian species. The best known lentivirus is the Human Immunodeficiency Virus (HIV), which causes AIDS. Lentiviruses are also hosted in apes, cows, goats, horses, cats, and sheep. Recently, lentiviruses have been found in monkeys, lemurs, Malayan flying lemur, rabbits, and ferrets. Lentiviruses and their hosts have worldwide distribution. Lentiviruses can integrate a significant amount of viral cDNA into the DNA of the host cell and can efficiently infect nondividing cells, so they are one of the most efficient methods of gene delivery. Lentiviruses can become endogenous (ERV), integrating their genome into the host germline genome, so that the virus is henceforth inherited by the host's descendants.
Gammaretrovirus is a genus in the retroviridae family. Example species are the murine leukemia virus and the feline leukemia virus. They cause various sarcomas, leukemias and immune deficiencies in mammals, reptiles and birds.
The genome and proteins of HIV have been the subject of extensive research since the discovery of the virus in 1983. "In the search for the causative agent, it was initially believed that the virus was a form of the Human T-cell leukemia virus (HTLV), which was known at the time to affect the human immune system and cause certain leukemias. However, researchers at the Pasteur Institute in Paris isolated a previously unknown and genetically distinct retrovirus in patients with AIDS which was later named HIV." Each virion comprises a viral envelope and associated matrix enclosing a capsid, which itself encloses two copies of the single-stranded RNA genome and several enzymes. The discovery of the virus itself occurred two years following the report of the first major cases of AIDS-associated illnesses.
The Baltimore classification, developed by David Baltimore, is a virus classification system that groups viruses into families, depending on their type of genome and their method of replication.
This glossary of genetics is a list of definitions of terms and concepts commonly used in the study of genetics and related disciplines in biology, including molecular biology and evolutionary biology. It is intended as introductory material for novices; for more specific and technical detail, see the article corresponding to each term. For related terms, see Glossary of evolutionary biology.
Gene therapy utilizes the delivery of DNA into cells, which can be accomplished by several methods, summarized below. The two major classes of methods are those that use recombinant viruses and those that use naked DNA or DNA complexes.
A negative-sense single-stranded RNA virus is a virus that uses negative sense, single-stranded RNA as its genetic material. Single stranded RNA viruses are classified as positive or negative depending on the sense or polarity of the RNA. The negative viral RNA is complementary to the mRNA and must be converted to a positive RNA by RNA polymerase before translation. Therefore, the purified RNA of a negative sense virus is not infectious by itself, as it needs to be converted to a positive sense RNA for replication. These viruses belong to Group V on the Baltimore classification.
This glossary of virology is a list of definitions of terms and concepts used in the study of virology, particularly in the description of viruses and their actions.
Bovine foamy virus (BFV) is a ss(+)RNA retrovirus that belongs to the genus spumaviridae. Spumaviruses are differ from the other six members of family retroviridae, both structurally and in pathogenic nature. Supma viruses derive their name from spuma the latin for "foam". The 'foam' part of 'foamy virus' comes from syncytium formation and the rapid vacuolization of infected cells which creates a 'foamy' appearance.
Black beetle virus (BBV) is a virus that was initially discovered on North Island of New Zealand in Helensville in dead New Zealand black beetles in 1975.
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