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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. [2] 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).
Rarely, retroviral integration may occur in a germline cell that goes on to develop into a viable organism. This organism will carry the inserted retroviral genome as an integral part of its own genome—an "endogenous" retrovirus (ERV) that may be inherited by its offspring as a novel allele. Many ERVs have persisted in the genome of their ...
First described in 1954 by Bjorn Sigurdsson in Iceland, [6] Maedi-visna virus was the first lentivirus to be isolated and characterized, accomplished in 1957 by Sigurdsson. [6] [7] [8] Maedi (Icelandic mæði 'dyspnoea') and visna (Icelandic visna 'wasting' [9] or 'shrinking' of the spinal cord) refer to endemic sheep herd conditions that were only found to be related after Sigurdsson's work.
The double stranded DNA is highly stable and easily integrated into a host genome. A few examples of the virus are Moloney murine leukemia virus, xenotropic MuLB-related virus, feline leukemia virus, and feline sarcoma virus. [6] [7] [8] Gammaretroviruses are very popular retroviral vectors in laboratory studies.
Today, research is carried out on ASLV in order to better understand retroviral cell entry. Since ASLV uses distinct cellular receptors to gain entry into cells, it has proven useful for understanding the early events in retroviral infection. [ 8 ]
For example, some protect against infection with related viruses. [ 10 ] [ 11 ] In some mammal groups, including higher primates , retroviral envelope proteins have been exapted to produce a protein that is expressed in the placental syncytiotrophoblast , and is involved in fusion of the cytotrophoblast cells to form the syncytial layer of the ...
Test results indicated that these animals were likely ill from H5N1 avian flu, which was first seen in wild birds in the United States in 2015," the county health department said on Dec. 11.
JSRV is the virus that is the cause of the contagious lung tumors in sheep called ovine pulmonary adenocarcinoma (OPA). The disease has also been called "jaagsiekte", after the Afrikaans words for "chase" (jaag) and "sickness" (siekte), to describe the respiratory distress observed in an animal out of breath from being chased, indicating the breathing difficulty experienced by infected sheep.