Measles virus polypeptide synthesis in infected cells

The synthesis of measles virus polypeptides has been studied using an inhibitor of virus-induced cell fusion, carbobenzoxy-d-phenylalanyl-l-phenylalanyl-nitro-l-arginine (SV4814). Cells infected at a multiplicity of 10 fuse extensively by 17 hr and die shortly thereafter, making it difficult to detect viral polypeptides. Cells protected from fusion by SV4814 survive and continue to produce virus, and the synthesis of viral polypeptides can be followed for 4 days. The previously described measles virion polypeptides G, 2, NP, 5, and M have been identified in infected cells, and, in addition, a polypeptide (L) with a molecular weight of ～200,000 has been found in infected cells and in small amounts in virions. (New designations suggested for polypeptides G, 2, and 5 are H, P, and F₁, respectively.) A glycosylated polypeptide (F₀, MW ～62,000) has also been found in infected cells, but not in virions. This polypeptide is thought to be the precursor of two polypeptides which appear under pulse-chase conditions: F₁ (MW ～40,000), which is not glycosylated, and F₂, a small glycosylated polypeptide detected with [³H]glucosamine labeling. In addition to facilitating studies of measles virus polypeptide synthesis, the use of SV4814 has shown that cell fusion is the major factor in early cell death caused by measles virus, but that cell death ultimately ensues in the absence of cell fusion, indicating another mechanism of measles virus-induced cell damage.     

Establishment of a persistently infected cell line with rinderpest virus

Summary Persistent infection of rinderpest virus in Vero cells was established and designated as VRP₃₄. Virus specific antigens were present in nearly 100 per cent of the cells. Cytopathic effect (CPE) consisting of syncytium formation and vacuolation is a unique feature of VRP₃₄.Spontaneously released virus mainly consisted of non-temperature-sensitive virus populations and was able to initiate persistent infection in both normal Vero and RK₁₃ cells. The results indicate that mutation of virus is responsible for the establishment of persistent infection.With 1 Figure     

Ribonucleic acid in peripheral blood cells

Summary The presence of RNA was investigated in the cells of peripheral blood of horses by Brachet's method. Monocytes contain many RNA granules, while the quantity of RNA granules in lymphocytes varies from single granules to a large number of them. Thus, it was demonstrated by the histochemical method that lymphocytes prossess different activity with regard to the functions caused by RNA. No RNA granules were revealed in other blood cells. The authors estimated the number of lymphocytes rich in RNA, of those containing a moderate amount, and those with only a few RNA granules.Presented by Active Member of AMN SSSR, G. V. Vygodchikov     

Viral nucleic acid synthesis in HSV infected neural cells

Summary HSV-1 replication and synthesis of viral DNA and RNA have been examined in gliomas of human (COX) and rat origin (C6) and in mouse neuroblastomas (D2). COX cells fully support HSV-1 replication and show patterns of viral DNA and RNA synthesis similar to those seen in continuous line cells. HSV-1 also grows to high titers in D2 cells but without concomitant high levels of viral DNA and RNA synthesis in the infected cells. Finally, HSV-1 established a persistent infection in C6 cells. Viral mRNA and DNA synthesis could not be detected in these cultures. At cycles of approximately 15–20 days, the persistently infected cultures exhibited massive CPE and relatively high production of infectious HSV.With 3 Figures     

Ribonucleic acid of barley yellow dwarf virus

Virions of the isolates of barley yellow dwarf virus transmitted by Macrosiphum avenae (MAV) and by Rhopalosiphum padi (RPV) contain a single component of single-stranded RNA of molecular weight 2.0 × 10⁶, estimated by sedimentation and gel electrophoretic mobility of formalinized RNA. The untreated ribonucleic acid of the RPV isolate appears to have a slightly more compact configuration than that of the MAV isolate, as shown by a slightly faster sedimentation coefficient (33.8 S vs 32.6 S) and a slightly faster migration rate in polyacrylamide gel electrophoresis. Virions of the MAV isolate had a $\text{280}\text{260}$ absorbance ratio of 0.52 and a $\text{230}\text{260}$ ratio of 0.82, whereas corresponding figures for RPV virions were 0.54 and 0.91. Both virions apparently have a high content of RNA.     

Macromolecular synthesis in L-A9 cells infected with Marituba virus

Summary Marituba virus induces a rapid and efficient shut-off of RNA and protein synthesis in mouse L-A9 cells. The time lag before the inhibition and the degree of inhibition itself are a function of the multiplicity of infection.With 2 Figures     

Enhancement of potato virus X synthesis in doubly infected tobacco occurs in doubly infected cells

Enhancement of potato virus X (PVX) synthesis by potato virus Y (PVY) or tobacco mosaic virus (TMV) in tobacco is the result of increased synthesis per cell, not an increase in the number of cells infected. Ultrastructural features typical of PVX-infected cells and those typical of PVY-infected cells were present together in a majority of cells examined by electron microscopy from leaves supporting enhancement. PVX was detected in over 70% of protoplasts prepared from infected leaves and stained with fluorescein-labeled PVX antibody; the proportion was the same for cells from doubly infected and singly infected leaves. In leaves infected with TMV and PVX, 70% of the cells were doubly infected. The fluorescence intensity of individual cells after treatment with fluorescein-labeled PVX antibody, a measure of relative virus concentration, was greater in cells from leaves doubly infected by PVX and PVY than in cells from leaves infected by PVX alone.     

Mitochondrial DNA synthesis in Raji cells infected by herpes simplex virus or Epstein-Barr virus

Mitochondrial DNA synthesis in herpes simplex virus infected Raji cells appears to be stimulated early in the infectious cycle in contrast to nuclear DNA synthesis which is progressively inhibited. This phenomenon cannot be observed in Raji cells abortively infected with Epstein-Barr virus.

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Zusammenfassung Die mitochondriale DNA-Synthese in Herpes-simplex-Virus-infizierten Raji-Zellen ist während der frühen Phase des Infektionscyclus gesteigert. Im Gegensatz dazu wird die nucleäre DNA-Synthese zunehmend gehemmt. Dieses Phänomen ist nicht in Raji-Zellen zu beobachten, die abortiv mit Epstein-Barr-Virus infiziert sind.

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This investigation was supported by the Deutsche Forschungsgemeinschaft.