Fine structure and morphogenesis of Borna disease virus

Borna disease virus (BDV), a negative nonsegmented single-stranded RNA viru s, has not been fully characterized morphologically. Here we present what i s to our knowledge the first data on the fine ultrastructure and morphogene sis of BDV. The supernatant of MDCK cells persistently infected with BDV tr eated with n-butyrate contained many virus-like particles and more BDV-spec ific RNA than that of untreated samples. The particles were spherical, enve loped, and approximately 130 nm in diameter; had spikes 7 nm in length; and reacted with BDV p40 antibody. A thin nucleocapsid, 4 nm in width, was pre sent peripherally in contrast to the thick nucleocapsid of hemagglutinating virus of Japan. The BDV particles reproduced by budding on the cell surfac e.