Cytopathology in the Identification and Classification of Tombusviruses

Abstract

Ten recognized members of the tombusvirus group, including two strains of tomato bushy stunt virus, were compared for their ultrastructural effects in Nicotiana clevelandii, Gomphrena globosa, and Chenopodium quinoa. The cytopathic inclusions known as multivesicular bodies and tonoplast evaginations containing virus particles were induced by all the viruses in all three hosts. Some of the viruses could be differentiated from each other (especially in C. quinoa) by other characters, such as the accumulation of membranes in cell nuclei, or the type of organelle (chloroplasts, mitochondria or peroxisomes) from which multivesicular bodies developed. The usefulness of these characters for virus identification and grouping is discussed.

Expression of the Cymbidium Ringspot Virus 33-Kilodalton Protein in Saccharomyces cerevisiae and Molecular Dissection of the Peroxisomal Targeting Signal

“…They consist of a main body surrounded by many spherical to ovoid vesicles 80 to 150 nm in diameter, resulting from proliferation of the limiting membrane of peroxisomes (22,33). Viral replication may take place in the vesicles of MVBs as suggested by the association of the p33/p92 proteins with modified peroxisomes in infected cells (1,21,29).…”

“…The accessibility to proteinase K digestion of the N-and C-terminal hydrophilic parts indicates that these regions are in the cytosolic side of the peroxisomal membrane. In analogy with the mitochondrial-directed p36 and complete replicase of CIRV (41), the complete replicase of CymRSV (p92) also probably has the topology N cyto -C cyto , being accessible to viral replication in the interior of the cytoplasm-connected vesicles developing from the peroxisomal membrane during plant cell infection (33). Electron microscopic analysis showed no vesiculation of peroxisomes where p33 accumulates, suggesting that other factors may contribute to the formation of MVBs.…”

New Approaches to the Detection of Microbial Plant Pathogens

“…These crystals appear to be composed of regularly arranged virus particles and the macro-structures, known as X-bodies or inclusion bodies, often have a characteristic morphology and cellular location (Bald, 1966;Christie and Edwardson, 1977;Edwardson and Christie, 1978;Russo, Di Franco and Martelli, 1987). The detection and identification of some plant viruses can be achieved readily by the observation of particular inclusion bodies that they induce in the cells they infect (Ko, 1988).…”

The membranous labyrinth in baculovirus-infected crustacean cells: possible roles in viral reproduction

“…Still other reports for avariety of viruses indicate the formation of cytoplasmic, membranous structures, such as annulate lamellae, multivesicular bodies, and concentric membrane masses from ER, outer nuclear envelope and other organelles (Kim & Boatman 1967, Merkow et al 1970 Russo et al 1987); usually, these authors did not suggest functions other than aberiant virus assembly processes for these membranous structures The derivation of the ML, in BP-crustacean cell systems, from the very flexible Golgi, outer nuclear envelope and ER, all part of the cytocavitary system of the cell (Trump & Arstila 1971, Porter & Bonneville 1968, and the known role of this membrane-bound system in cells, suggests that viruses could turn thls role of packaging and transporting proteln and complex carbohydrates to their own needs in reproduction. If this were the case in the ML, then the direction of flow of these proteins and perhaps other precursor substance would be (under virus control) largely reversed toward the nucleus where nuclear, DNA virus assembly and occlusion body formation occurs, rather than toward the plasma membrane where normal secretion of synthesized, cellular products occurs.…”