The Role of Endogenous Retroviruses in the Domestication Process

Endogenous retroviruses (ERVs) play an important role in the expression regulation of many animal and human genes and are involved in the processes of transcriptional and posttranscriptional editing. ERVs retain a certain genetic similarity to the exogenous generic virus. ERV research helps to determine the age and rate of evolution of exogenous viruses that are contagious to animals and humans. It is hypothesized that retroviruses arose before the appearance of vertebrates. This asynchrony suggests a significant contribution of retroviruses to the evolutionary development of organisms. ERVs have no species boundaries due to horizontal transfer; however, the movement of retrotransposons in the genome of animals can lead to cytogenetic defects and have a negative effect on the fitness of organisms. One striking example of horizontal transfer is the LINE 1 retrotransposon, which was found in 559 species, including animals, plants, and fungi. This confirms the assumption about the time of the emergence of retroviruses. Retrotransposons, which participate in the processes of transposition and recombination, cause changes in DNA nucleotide sequences. This leads to mutational processes in genes, in particular, those responsible for the development of neurons in the brain and nervous system, i.e., retrotransposons may be responsible for domestication syndrome. The infection of germ cells with retroviruses gradually led to their establishment of reproductive functions in mammals. These functions include the fusion of trophoblasts in the placenta. ERV genes are incorporated into the genome via viral infections or retrotransposition. The review systematizes and summarizes the knowledge of the evolution and transfer of ERVs in the body and their functions in the genome and describes the main and most common ERVs, as well as their molecular structure and properties.