biologia: Endogenous retrovirus

Evidence: 100 • authority: 72

Endogenous retroviruses (ERVs) are endogenous viral elements in the genome that closely resemble and can be derived from retroviruses. They are abundant in the genomes of jawed vertebrates, and comprise up to 5–8% of the human genome (lower estimates of 3%). ERVs are vertically inherited proviral sequences, and they form a subclass of a type of gene called transposons, which can normally be packaged and moved within the genome to serve a vital role in gene expression and in regulation. ERVs, however, lack most transposon functions, are typically not infectious, and are often defective genomic remnants of the retroviral replication cycle. They are distinguished as germline provirus retroelem…

Evidence: 42 • authority: 72

A retrovirus is a virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. After invading a host cell's cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern, thus retro (backward). The new DNA is then incorporated into the host cell genome by an integrase enzyme, at which point the retroviral DNA is referred to as a provirus. The host cell then treats the viral DNA as part of its own genome, transcribing and translating the viral genes along with the cell's own genes, producing the proteins required to assemble new copies of the virus. Man…

Evidence: 40 • authority: 92

Jawless vertebrates do not escape retrovirus infection.. On occasion, retroviruses infect the genome of germline cell, forming endogenous retroviruses (ERVs), which provide molecular fossils for studying the deep evolution of retroviruses. While ERVs have been extensively characterized in the genomes of jawed vertebrates, much remains contentious and unexplored about the diversity and evolution of ERVs within jawless vertebrates. Here, we report the discovery of a novel ERV lineage, designated EbuERVs, in the genome of a hagfish Eptatretus burgeri. Phylogenetic analyses show that EbuERVs pertain to epsilon-retroviruses and might have derived from cross-species transmission from jawed verteb…

Evidence: 40 • authority: 92

Mix-and-match between transposable elements and zinc finger proteins fuels genic and regulatory innovation.. Transposable elements (TEs) are abundant and dynamic components of eukaryotic genomes, subject to regulation by equally adaptive regulatory systems. A coevolution of TEs and zinc finger genes can be documented throughout metazoan evolution. In humans, TEs account for half of the genome, and nearly all TE subfamilies are preferentially bound by at least one of the approximately 400 KRAB zinc finger proteins (ZFPs). The majority of human KRAB-ZFPs appear to tame the cis-regulatory activities of TEs, thereby facilitating their integration within gene regulatory networks. In turn, throug…

Evidence: 40 • authority: 72

Human endogenous retrovirus K (HERV-K) or Human teratocarcinoma-derived virus (HDTV) is a family of human endogenous retroviruses associated with malignant tumors of the testes. Phylogenetically, the HERV-K group belongs to the ERV2 or Class II or Betaretrovirus-like supergroup. Over the past several years, it has been found that this group of ERVs play an important role in embryogenesis, but their expression is silenced in most cell types in healthy adults. The HERV-K family, and particularly its subgroup HML-2, is the youngest and most transcriptionally active group and hence, it is the best studied among other ERVs. Reactivation of it or anomalous expression of HML-2 in adult tissues has…

Evidence: 38 • authority: 92

Evidence: 38 • authority: 72

Human Endogenous Retrovirus-W (HERV-W) is a family of Human Endogenous Retroviruses (HERVs). HERVs are part of a superfamily of repetitive and transposable elements. Transposable elements are sequences of DNA that can move or "jump" around the genome, sometimes replicating and inserting themselves in different locations. There are 31 known families of HERVs, constituting approximately about 8% of the human genome of which HERV-W DNA encoding sequences specifically account for about 1% of the human genome. For comparison, this represents about the same amount of DNA allocated to protein coding genes. Most HERVs in the genome today are not able to replicate, because of genetic changes such as…

Evidence: 36 • authority: 88

Evidence: 24 • authority: 72

Endogenization is the evolutionary process by which viral genetic material becomes stably integrated into the germline of a host organism and inherited by offspring through Mendelian inheritance. The integrated sequences become endogenous viral elements, which encompasses all inheritable virus-derived sequences regardless of virus type. Essentially, a successful endogenization event can transform what had been an exogenous pathogen into a fixed, inheritable component of the host's own genome. This can have a wide range of repercussions within the host, or it can have none at all. The molecular mechanisms driving this process vary among virus and host types. It can more commonly occur from t…

Evidence: 22 • authority: 80