The central nervous system of wound tumor virus (WTV)-infected Agallia constricta was studied by electron microscopy to obtain information concerning the virus distribution in the nervous system. Wound tumor virions were mostly found in the cytoplasm of the ganglion cells and less frequently in the glial cells. WTV was occasionally observed in the perineurium cells, nerve axons, tracheoblasts, and lateral nerves. In the ganglion cells, virions appeared as individual isolated particles (V(1)), in tubular formation (V(2)), and occasionally in aggregates (V(3)). In the glial cells, the virions were mostly seen in the V(3) formation, and very seldom in the V(1) and V(2) formations. In the perineurium cells and tracheoblasts, only small V(3) formations were observed. The isolated virions were usually surrounded with polyribosomes, and often appeared around the foci of the viroplasm. Sometimes degenerating ganglion cells infected with the WTV were encountered. These damaged cells strongly indicated that WTV exerted a cytopathogenic effect on the nerve cells.

Central Nervous System↗

PubMed1967

Electron microscopy of the formation of wound tumor virus in abdominally inoculated insect vectors.

Fifth-instar nymphs of Agallia constricta leafhoppers were injected abdominally with extracts from root tumors confining wound tumor virus (WTV). The insects were sacrificed at predetermined intervals, their internal organs dissected, fixed, embedded, sectioned, stained, and examined in a Siemens Elmiskop I. Sequential stages in virus development were reconstructed from consecutive samples of fatbody tissues. Changes resulting from the infection were: (i) a viroplasm, i.e., an accumulation of electron-dense aggregates; (ii) the appearance at the periphery of the viroplasm of a few fully formed virus particles recognized as virions; (iii) the formation of increasing numbers of individual virions, not only at the periphery but also in the viroplasm; (iv) the engulfing of virions within multimembranous structures; and (v) the formation of virus microcrystals either at the sites of former viroplasms, or at some distance. These morphological findings indicate that, following abdominal inoculation of WTV, the plant-pathogenic virus develops within the cytoplasmic matrix proper of insect vector cells. In addition to the fatbody tissues, WTV was detected in the epidermis, muscles, and trachea of abdominally inoculated insects, demonstrating the systemic invasion of the mechanically infected arthropod host. No virus was found in the gut tissues.

Journal Article↗

PubMed1966