Search results
Results From The WOW.Com Content Network
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).
A number of satellite viruses—viruses that require the assistance of another virus to complete their life cycle—are also known. Their taxonomy has yet to be settled. The following four genera have been proposed for positive sense single stranded RNA satellite viruses that infect plants— Albetovirus , Aumaivirus , Papanivirus and ...
However, there is a key difference between retroviruses and retrotransposons, which is indicated by the env gene. Although similar to the gene carrying out the same function in retroviruses, the env gene is used to determine whether the gene is retroviral or retrotransposon.
An example of an acute transforming virus is the Rous Sarcoma Virus (RSV) that carry the v-src oncogene. v-Src is part of the c-src, which is a cellular proto-oncogene that stimulates rapid cell growth and expansion. A non-acute transforming virus on the other hand induces a slow tumor growth, since it does not carry any viral oncogenes.
The replication cycle of a retrovirus entails the insertion ("integration") of a DNA copy of the viral genome into the nuclear genome of the host cell.Most retroviruses infect somatic cells, but occasional infection of germline cells (cells that produce eggs and sperm) can also occur.
The virus may induce the cell to forcefully undergo cell division, which may lead to transformation of the cell and, ultimately, cancer. An example of a family within this classification is the Adenoviridae. There is only one well-studied example in which a class 1 family of viruses does not replicate within the nucleus.
Identical LTR sequences at either end of a retrotransposon. 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.
LTR retrotransposons have direct long terminal repeats that range from ~100 bp to over 5 kb in size. LTR retrotransposons are further sub-classified into the Ty1-copia-like (Pseudoviridae), Ty3-like (Metaviridae, formally referred to as Gypsy-like, a name that is being considered for retirement [4]), and BEL-Pao-like (Belpaoviridae) groups based on both their degree of sequence similarity and ...