Endogenous Bornavirus Like Nucleoprotein 1 (EBLN1)

Elements homologous to the nucleoprotein (N) gene of bornavirus exist in the genomes of several mammalian species, including humans, non-human primates, rodents and elephants. These sequences have been designated endogenous Borna-like N elements. Some of the primate EBLNs contain an intact ORF and are expressed as mRNA. EBLNs seem to have been generated by different insertional events in each specific animal family. Furthermore, the EBLN of a ground squirrel was formed by a recent integration event, whereas those in primates must have been formed more than 40 million years ago. The N mRNA of a current mammalian bornavirus, Borna disease virus (BDV), can form EBLN-like elements in the genomes of persistently infected cultured cells. Therefore, integration of EBLN-1 must have occur through a mechanism relying on an endogenous reverse transcriptase activity.