Using a method for freeze-drying intact cells, uninfected and murine leukemia virus (MuLV)-infected JLSV9 cell surfaces, as well as murine mammary tumor virus (MuMTV)-infected cell surfaces, were examined by electron microscopy. The 10-nm knobs of MuLV and the 5-nm spikes of MuMTV were clearly revealed on the surfaces of budding viruses and were also found dispersed over the cell surface. The MuLV knobs are randomly arranged on the virus surface, whereas the MuMTV spikes are much more ordered. Because freeze-fractured budding viral envelopes are devoid of intramembranous particles, the observed surface particles do not appear to be merely accentuated intramembranous particles. This technique should permit further analysis of the morphogenesis of viral envelopes without the need for externally applied labels.

Cell Line↗

PubMed1976

Surface structure of virions budding from L1210(V) gln- mouse leukemia cells.

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Animals↗

PubMed1976

Characteristics of a surface-adherent subline derived from Friend erythroleukemia cells in continuous suspension culture.

A surface-adherent cell population developed spontaneously from Friend erythroleukemia cells (FLC745) which previously had grown continuously in suspension cultures. The adherent cells have been transferred through more than 60 passages and apparently represent a stable variant, herein designated FLC745-Ad. The cell size, chromosome complement, and tumorigenicity in DBA/2 mice were similar to the parental FLC745 line, although the FLC745-Ad cultures grew at a slightly slower rate and synthesized less hemoglobin in response to dimethyl sulfoxide. Production of C-type particles was abundant in both suspension and adherent cells, but the latter appeared to contain more intracisternal A-type particles. Scanning electron microscopy disclosed that most adherent cells were globoid and nonspreading. They attached to the substrate by a circumferential lamellar skirt of unusual breadth. Adhesion of the FLC745-Ad cells was not influenced by serum concentration, trypsinization, 5-bromodeoxyuridine, or N6, O2'-dibutyryl adenosine 3':5'-monophosphate. Treatment with cytochalasin B increased the cell size and the area of cell attachment.

Animals↗

PubMed1975

Morphological, chemical, and antigenic organization of mammalian C-type viruses.

New features in the architecture of mammalian type C viruses, in particular knoblike surface projections and hexagonally arranged subunits on the core shell could be demonstrated by electron microscopy, taking advantage of newly developed preparation techniques. As examples, murine leukemia viruses (MuLVs) and newly isolated porcine and bovine C viruses are presented. The major proteins of a MuLV were isolated and partially characterized in chemical terms and with respect to their serological and other biological activities, such as interfering and hemagglutinating (HA) capacity. Most of the characterized proteins could be localized in particular substructures of the virion either by selective removal or isolation of electron microscopically identifiable constituents. The information obtained allowed the design of a more detailed model of mammalian C viruses. Special attention was devoted to the further characterization of interspecies antigens of mammalian C viruses. Different antigenic determinants were revealed. Their distribution allows further subgrouping of mammalian C viruses.

AKR murine leukemia virus↗