Purification and partial characterization of a new enveloped RNA virus (Berne virus)

Abstract

In 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). Binding 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).