A retrovirus is a type of 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. Once inside the 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 (backwards). 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.
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 viruses such as HIV and hepatitis B to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, and by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes. Contrary to a widely held belief, the process does not violate the flows of genetic information as described by the classical central dogma, as transfers of information from RNA to DNA are explicitly held possible.
Orthomyxoviridae is a family of negative-sense RNA viruses. It includes seven genera: Alphainfluenzavirus, Betainfluenzavirus, Gammainfluenzavirus, Deltainfluenzavirus, Isavirus, Thogotovirus, and Quaranjavirus. The first four genera contain viruses that cause influenza in birds and mammals, including humans. Isaviruses infect salmon; the thogotoviruses are arboviruses, infecting vertebrates and invertebrates. The Quaranjaviruses are also arboviruses, infecting vertebrates (birds) and invertebrates (arthropods).
Kaposi's sarcoma-associated herpesvirus (KSHV) is the ninth known human herpesvirus; its formal name according to the International Committee on Taxonomy of Viruses (ICTV) is Human gammaherpesvirus 8, or HHV-8 in short. Like other herpesviruses, its informal names are used interchangeably with its formal ICTV name. This virus causes Kaposi's sarcoma, a cancer commonly occurring in AIDS patients, as well as primary effusion lymphoma, HHV-8-associated multicentric Castleman's disease and KSHV inflammatory cytokine syndrome. It is one of seven currently known human cancer viruses, or oncoviruses. Even after so many years of discovery of KSHV/HHV8, there is no known cure for KSHV associated tumorigenesis.
An oncovirus or oncogenic virus is a virus that can cause cancer. This term originated from studies of acutely transforming retroviruses in the 1950–60s, when the term "oncornaviruses" was used to denote their RNA virus origin. With the letters "RNA" removed, it now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with "tumor virus" or "cancer virus". The vast majority of human and animal viruses do not cause cancer, probably because of longstanding co-evolution between the virus and its host. Oncoviruses have been important not only in epidemiology, but also in investigations of cell cycle control mechanisms such as the retinoblastoma protein.
Poultry diseases occur in poultry, which are domesticated birds kept for their meat, eggs or feathers. Poultry species include the chicken, turkey, duck, goose and ostrich.
Alpharetrovirus is a genus of the family Retroviridae. It has type C morphology. Members can cause sarcomas, other tumors, and anaemia of wild and domestic birds and also affect rats.
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.
Rous sarcoma virus (RSV) is a retrovirus and is the first oncovirus to have been described. It causes sarcoma in chickens.
A long terminal repeat (LTR) is a pair of identical sequences of DNA, several hundred base pairs long, which occur in eukaryotic genomes on either end of a series of genes or pseudogenes that form a retrotransposon or an endogenous retrovirus or a retroviral provirus. All retroviral genomes are flanked by LTRs, while there are some retrotransposons without LTRs. Typically, an element flanked by a pair of LTRs will encode a reverse transcriptase and an integrase, allowing the element to be copied and inserted at a different location of the genome. Copies of such an LTR-flanked element can often be found hundreds or thousands of times in a genome. LTR retrotransposons comprise about 8% of the human genome.
Env is a viral gene that encodes the protein forming the viral envelope. The expression of the env gene enables retroviruses to target and attach to specific cell types, and to infiltrate the target cell membrane.
The Infectious bronchitis virus D-RNA is an RNA element known as defective RNA or D-RNA. This element is thought to be essential for viral replication and efficient packaging of avian infectious bronchitis virus (IBV) particles.
Avian sarcoma leukosis virus (ASLV) is an endogenous retrovirus that infects and can lead to cancer in chickens; experimentally it can infect other species of birds and mammals. ASLV replicates in chicken embryo fibroblasts, the cells that contribute to the formation of connective tissues. Different forms of the disease exist, including lymphoblastic, erythroblastic, and osteopetrotic.
Retroviral matrix proteins are components of envelope-associated capsids of retroviruses. These proteins line the inner surface of viral envelopes and are associated with viral membranes.
Peter K. Vogt is an American molecular biologist, virologist and geneticist. His research focuses on retroviruses and viral and cellular oncogenes.
An endogenous viral element (EVE) is a DNA sequence derived from a virus, and present within the germline of a non-viral organism. EVEs may be entire viral genomes (proviruses), or fragments of viral genomes. They arise when a viral DNA sequence becomes integrated into the genome of a germ cell that goes on to produce a viable organism. The newly established EVE can be inherited from one generation to the next as an allele in the host species, and may even reach fixation.
Karen Beemon is an American molecular biologist whose research focuses primarily on viruses, RNA, and the genetic causes of cancer. She determined the size of retroviral genomes as a graduate student and subsequently helped characterize the Src oncogene of Rous sarcoma virus, the first tyrosine kinase. Her work on retroviral RNA processing has included mapping m6A modification sites in retrovirus genomes and determining a consensus sequence (RGACU). She also identified a Negative Regulator of Splicing sequence and an RNA-stability element that prevents nonsense-mediated decay of viral and cellular RNAs. Recently, Beemon identified tumor-promoting genes whose expression is altered by integration of the Avial Leukosis Virus (ALV) into the genome, such as the telomerase catalytic subunit, TERT.
Leslie J. Parent is an American microbiologist and immunologist currently professor and vice dean of the College of Medicine at Pennsylvania State University and an Elected Fellow of the American Association for the Advancement of Science and American Society for Microbiology.
Harry Rubin – February 2, 2020) was an American cell biologist and virologist. He is known for his experimental research on oncoviruses and how cellular microenvironment and cellular aging affect the regulation of cancerous tumors.
