Purification and Partial Characterization of a New Enveloped RNA Virus (Berne Virus)

Abstract

SUMMARYIn Berne (Switzerland), a virus was isolated from a horse which was found to be serologically unrelated to known equine viruses. Its growth was unaffected by iododeoxyuridine and it was inactivated by organic solvents. A purification procedure involving ammonium sulphate precipitation and sucrose gradient equilibrium centrifugation was developed and viral activities were monitored using infectivity and enzyme-linked immunosorbent assays. Purified virions of density 1-16 g/ml were shown by negative staining electron microscopy to be roughly spherical and to measure 120 to 140 nm in diameter; projections (peplomers, about 20 nm long) were identified on the virion surface. In thin sections, an envelope and an elongated core structure could be distinguished. The core, measuring about 23 nm across and 104 nm in length, appears to assume a rod-, crescent-or open ring-shape within the envelope. It has a tubular structure and shows a transverse striation (periodicity 4.5 nm). Budding at the plasma membrane was observed. Berne virus is considered as a representative of a hitherto undefined family of widespread animal viruses serologically related to recent bovine isolates in Ames, Iowa (U.S.A.) and Lyon (France).

A Morphological Study of the Replication of Breda Virus (Proposed Family Toroviridae) in Bovine Intestinal Cells

“…Breda virus appears to be closely related to Berne virus, a newly characterized enteric virus of horses (Weiss et aL, 1983), and probably to an enteric virus of humans (Beards et al, 1984). Berne virus, which has been cultured in vitro, measures 120 to 140 nm in diam.…”

“…wt. (20K) in the nucleocapsid (Weiss et al, 1983;Horzinek et al, , 1985. Replication of both Berne virus and Breda virus involves the host cell nucleus.…”

The Haemagglutinating Activity of Berne Virus

“…The viral membrane is seen at a distance of 18 + 3-4 nm (n = 37) from the erythrocyte membrane. Since the unfixed peplomers of Berne virus were shown to measure 20 nm in length in negatively stained preparations (Weiss et al, 1983) this suggests that the haemagglutinating activity is due to the viral spikes formed by the 75K to 100K glycosylated protein .…”

“…For comparison, influenza A/swine/Germany/2/81 (H1N1) was tested in parallel with Berne virus. As shown in Table 2 haemagglutination was reduced by pretreatment of the erythrocytes with 0.5 mM-periodate and in the presence of bovine brain (11) was as previously described (Weiss et al, 1983). Agglutinating activity (if]) was measured as described in the text.…”

Characterization of defective interfering RNAs of Berne virus

“…In addition, intracellular RNA was isolated from the same cells after each passage (Snijder et al, 1988). Titrations of BEV infectivity were performed as described previously (Weiss et al, 1983).…”