A Comparison of the Changes in Fine Structure of L Cells During Single Cycles of Viral Multiplication, Following Their Infection With the Viruses of Mengo and Encephalomyocarditis

Abstract

The virus of encephalomyocarditis (EMC), examined by the negative-contrast method, is indistinguishable from the serologically related Mengovirus. The particles are 270 to 280 A in diameter. The surface of EMC is composed of an undetermined number of subunits. Frequent sampling of infected cells was carried out throughout one-step cycles of viral multiplication to observe cytopathic changes occurring in L cells infected by these two related RNA viruses. EMC and Mengovirus, which multiply at equal rates, in most respects elicit similar alterations in cell fine structure. Rearrangement and changes in nuclear material accompanied by formation of small vesicles in the centrosphere region commence at 4 to 6 hours after infection. Thereafter a progressive degeneration of the nucleus and vesiculation of the cytoplasm are observed up to 18 to 20 hours. Increased numbers of small dense granules, indistinguishable from ribonucleoprotein particles, appear in the cytoplasm between 8 and 14 hours after infection. L cells infected with Mengovirus become permeable to Erythrocin more slowly than those infected with EMC. Only in the case of Mengovirus infection are large aggregates of dense material first observed in the cytoplasm at 8 hours, followed by the appearance of crystals probably composed of Mengovirus particles, at 12 hours. Differences in the rates of cell permeability after infection with EMC and Mengovirus are discussed in relation to formation of virus crystals and plaque-type mutants.

Comparison of Mitotic Phenomena and Effects Induced by Hypertonic Solutions in Hela Cells

“…6) ; likewise, ethionine (20) and mengovirus (21) have been reported to induce chromatin clumping ; however, it is our impression that these effects are qualitatively quite different from those shown in Fig . 1 b T. YOUDALE .…”

Viral Hepatitis in Encephalomyocarditis Virus-Infected Mice

“…The cytopathic changes which were observed electron microscopically in the infected mouse liver were similar to those previously described for viral infected L cells [16], The observation of vésiculation and vacuoliza tion of membranous components is consistent with earlier observations of other EMC virus-infected tissues [7-11. 13, 22J, of tissues infected with Coxsackie virus B, (12), and of L cells infected with Mengovirus (1,2).…”

Localization of Hepatitis A Virus Antigen to Specific Subcellular Fractions of Hepatitis-A-Infected Chimpanzee Liver Cells

“…The presence of HAV antigen within cyto plasmic vesicles [18] or scattered throughout the cytoplasmic matrix of hepatocytes is rem iniscent of the morphologic observations re ported for poliovirus and other small RNA viruses during their replicative cycle [15,16,34]. In poliovirus replication, the whole growth cycle is confined to the cytoplasm [13], where viral RNA replication, protein synthesis, and virus assembly all occur in close association with membranes [14].…”