Electron microscopic studies of bovine viral diarrhea virus in tissues of diseased calves and in cell cultures

Abstract

Pathomorphological studies by electron microscopy (EM) were carried out on the intestines and lymphoid tissues, the buffy coat cells and cultured lymphocytes from calves suffering from mucosal disease (MD). This led to the detection of particles, 45--55 nm in diameter, within characteristic vesicular structures. As these findings coincided with the isolation of bovine viral diarrhea virus (BVDV) from the same tissues and demonstration of BVDV-antigen by immunocytochemical techniques in corresponding samples, the particles were tentatively identified as the BVDV. A detailed study of in vitro infected bovine cell cultures corroborated this supposition and contributed to a conjectural evaluation of the viral morphogenesis. It revealed a difference from the morphogenesis of most other togaviruses, as the presumed virions were assembled within smooth-membraned vesicles, formed during the infection. Thus, in the material examined, a budding process was not involved in the development of BVDV.

The Ultrastructure of Cell Cultures Infected with Border Disease and Bovine Virus Diarrhoea Viruses

“…This range contrasts with the size reported here of 46 nm which is in close agreement with the diameter of 50 nm reported by Ritchie & Fernelius (1969), Chasey & Roeder (1981) and Ohmann & Bloch (1982). Chasey & Roeder (1981) reported the presence of tubules in infected cells but unlike the present study did not observe virus particles within them.…”

“…One previous study of BDV and BVDV in tissue sections has been made (Scott et al, 1977) but later studies of BVDV from the same laboratory by Chasey & Roeder (1981) concluded that the particles described were non-viral. Other studies of BVDV in thin sections have been made by Ritchie & Fernelius (1969) and Ohmann & Bloch (1982) who described BVDV virus as spherical particles approximately 50 nm in diameter. Most studies of BVDV have utilized suspensions of virus and negative staining (Hafez et al, 1968;Maess & Retzko, 1970;Horzinek et al, 1971 ;Stott et al, 1974;Chu & Zee, 1984), and have variously reported the virus as roughly spherical and from 30 to 100 nm or more in diameter.…”

Morphogenesis of Pestiviruses: New Insights from Ultrastructural Studies of Strain Giraffe-1

“…It has been reported by others that pestivirions are released from large vacuoles in large numbers and/or aggregates (21,40). However, the described vacuoles may represent MVBs, and the observed particles may represent ILVs instead of virions, especially since the authors observed particles with identical morphology in vacuoles of uninfected cells.…”

Togaviridae

“…The molecular weights of the structural proteins are: E! and E2, (50-59) x I03; E3 (when present), 10 x 103; C, (30)(31)(32)(33)(34) x 103 [6]. The gene sequence is 5'nsPl-nsP2-nsP3-nsP4-C-E3-E2-El-3', con firmed from the complete nucleotide se quence of Sindbis virus RNA [9].…”

“…Very little informa tion is available on their replication; only a single species of virus-specific RNA [relative molecular mass (Mr) about 3 x 10''] with anomalous sedimentation behavior and un usual RNase resistance was identified in cells infected with mucosal disease virus [30]. Vir ions accumulate within the cisternae of mem branous organelles [4,11,12,31]. The three species in the genus show antigenic relation ships by immunodiffusion, antibody neutral ization, and fluorescence [11,12).…”