Bovine ephemeral fever virus in cell culture and mice

Abstract

Light, immunofluorescent and electron microscopic observations were carried out sequentially on mice and VERO cell cultures infected with bovine ephemeral fever (BEF) virus. In early harvests from cell culture, 185 • 73 nm cone-shaped particles with nearly parallel sides predominated; these particles had all other features typical of the Rhabdoviruses (surface projections, envelope, axial channel, precisely coiled helical nucleocapsid with 35 cross-striations at a 4.8 nm interval). Identical particles were the most frequent form in mouse brain. Variation in shape toward more broadly based cone-shapes occurred late in infection and reflected anomalous morphogenesis or particle breakdown. T (truncated) particles were common at all stages of infection. It was concluded that the reported variation in length and shape of particles in various BEF virus isolates is not necessarily releated to "strain variation" but more likely to varying growth rates and T particle interference associated with varying degrees of adaptation to a host system. BEF viral morphogenesis took place primarily upon plasma membranes in vivo and in cell culture in association with small accumulations of intraeytoplasmic matrix. Fusion of viral envelopes was observed, and an early syncytium formation occurred in infected cell cultures. Cytopathology was similar in vivo and in cell culture; a protracted stage of cell rounding was followed by extreme cytoplasmic vacuolation and condensation and then by lysis. Necrotic encephalomyelitis was severe in moribund mice but extraneural sites of viral propagation and damage were not found with any of the techniques employed. Since this strict neurotropism is most likely not characteristic of naturally acquired BEF virus infection in nature, it was concluded that the mouse was an unsatisfactory host for the further study of pathogenesis.

Genome organization and transcription strategy in the complex GNS-L intergenic region of bovine ephemeral fever rhabdovirus.

“…BEFV is serologically related to several other rhabdoviruses which infect cattle including Adelaide River virus (ARV), Berrimah virus and Kimberley virus (Calisher et al, 1989) and these have also been classified in the genus Ephemerovirus (Wunner et al, 1995). Like other rhabdoviruses, BEFV virions are bullet-or cone-shaped (Murphy et al, 1972), comprising a ribonucleoprotein complex and an envelope and containing a negative single-stranded RNA genome and five structural proteins (Della-Porta & Brown, 1979 ;Walker et al, 1991). Amino acid sequence analysis of the BEFV nucleoprotein (N) has indicated a close relationship to that of ARV and similarity to other animal rhabdoviruses with higher overall homology to vesiculoviruses than to lyssaviruses Wang et al, 1995).…”

Proteins of Bovine Ephemeral Fever Virus

“…The classification of BEFV as a rhabdovirus was established on the basis that it has bullet-shaped virions containing a 42S ssRNA genome and proteins of similar Mr to those of vesicular stomatitis virus (VSV) and rabies virus (Murphy et al, 1972;Della-Porta & Brown, 1979). However, it has been reported that, unlike other rhabdoviruses, BEFV contains six structural proteins, including an NS protein and two matrix proteins.…”

Isolation and cultivation of bovine ephemeral fever virus in chickens and chicken embryos

“…A portion of each organ was used to prepare a 20% suspension which was titrated in unweaned mice. Another portion of each organ was used to prepare frozen sections which were fixed in acetone and stained with fluorescein-conjugated BEF virus immune mouse ascitic fluid as described by Murphy, Taylor, Mims & Whitfield (1972). Control preparations consisted of sections from normal chicken embryos and fluorescein conjugated globulin from normal mouse ascitic fluid.…”