[Bornaviruses].

Bornaviridae is an enveloped animal virus carrying an 8.9 kb non-segmented, negative-strand RNA genome. The genus bornavirus contains two members infecting vertebrates, Borna disease virus (BDV) and avian bornavirus (ABV), which could preferably infect the nervous systems. BDV causes classical Borna disease, a progressive meningoencephalomyelitis, in horses and sheep, and ABV is known to induce proventricular dilatation disease, a fatal disease characterized by a lymphocytic, plasmacytic inflammation of central and peripheral nervous tissues, in multiple avian species. Recent evidences have demonstrated that bornavirus is unique among RNA viruses as they not only establish a long-lasting, persistent infection in the nucleus, but also integrate their own DNA genome copy into the host chromosome. In this review, I outline the recent knowledge about the unique virological characteristics of bornaviruses, as well as the diseases caused by the infection of BDV and ABV.