Electron microscope observations on intracellular virus-like particles associated with the cells of the Lucké renal adenocarcinoma

Characterization of the growth of herpes simplex virus in human lymphoid cells

Herpes simplex virus was grown in a 6-liter suspended culture of an atypical permanent human lymphoid cell line, Roswell Park Memorial Institute no. 8226. The kinetics of virus replication were determined by counting viruses by electron microscopy, plaque formation, and tissue culture infectivity. Deoxyribonucleic acid-dependent deoxyribonucleic acid polymerase activity was determined during the course of infection. Electron microscopy studies substantiated the kinetics of the virus infection in lymphoid cells.

Zonal centrifuge applied to the purification of Herpesvirus in the Lucké frog kidney tumor

A series of "winter" and "summer" Lucké kidney tumors of the frog (Rana pipiens) were homogenized and fractionated by differential centrifugation into nuclear, mitochondrial, and mitochondrial supernatant fractions. Winter tumors often contained high concentrations of herpesvirus, whereas no virus was observed in any of the summer tumors. The crude tumor fractions were further purified by rate-zonal sucrose gradient centrifugation in a B-XV zonal rotor. Gradient fractions rich in an enveloped, nucleated form of the herpesvirus from certain winter tumors have induced renal tumors when injected into developing frog embryos. Zonal centrifugation was followed by isopycnic banding of the virus zones for further purification of the different morphological forms of the virus.

Marek's disease herpes virus: a cytomegalovirus

The DNA of herpes viruses associated with Marek's disease of fowl contains 56-57 moles of guanine and cytosine per 100. The composition of its DNA and lack of infectiousness of cell-free preparations suggest that the herpes virus associated with Marek's disease belongs to the herpes virus group B which contains predominantly cytomegaloviruses.

Tumor induction in developing frog kidneys by a zonal centrifuge purified fraction of the frog herpes-type virus

Injection of frog embryos (Rana pipiens) with a zonal centrifuge purified fraction of herpes-type virus (prepared from virus-containing Lucké tumors) resulted in a high incidence of kidney tumors. This partially purified oncogenic fraction contained a high concentration of an enveloped form of the frog herpes-type virus (adjacent fractions lacked this particle and were not oncogenic), which suggests that this form of the virus plays a role in the genesis of the Lucké tumor.

Herpes-type virus of the frog renal adenocarcinoma. I. Virus development in tumor transplants maintained at low temperature

Development of the herpes-type virus of the frog kidney tumor was investigated by electron microscopy and high-resolution autoradiography in eyechamber transplants of tumor maintained at 7.5 C for up to 27 weeks. Virus particles were first detected at 10 weeks in nuclei containing aggregates of dense granular material. The initial incorporation of a pulse of (3)H-thymidine into these aggregates indicated that they contained newly synthesized viral deoxyribonucleic acid. Capsids enclosing doubleshelled cores were labeled with (3)H-thymidine before capsids with dense cores, and intermediate core forms were observed, suggesting that the double-shelled core transforms into the dense core. Particles with dense cores were observed while being enveloped by budding through the inner membrane of the nuclear envelope, and subsequently while being unenveloped in passing through the outer membrane into the cytoplasm. Virus particles within the cytoplasm acquired fibrillar coats and budded into vesicles, from which they were released, in enveloped form, at the cell surface. Tubular forms and particles considerably smaller than virus particles were regularly encountered in infected nuclei, and the relationship of these forms to virus replication is discussed.

Filamentous structures of type 2 Herpesvirus hominis infection of the chorioallantoic membrane

In view of recent recognition of the existence of two Herpesvirus hominis (HVH) types with antigenic and biological differences, an electron microscopic study was undertaken of pocks produced on the choriallantoic membrane of embryonated eggs after infection with type 1 and type 2 HVH strains. Besides the typical morphological features of herpesvirus infection noted by several investigators, it was observed that type 2 HVH also produced microtubules measuring approximately 19 nm in both nucleus and cytoplasm. Although the nature of these filamentous structures is still unclear, consideration is given in this paper to the possibility that they may represent viral structural subunits, aberrant forms or neoantigens.

Electron microscopic localization of herpesvirus-type particles in Marek's disease

Upon cultivation of chicken lymphoid tumors induced by Georgia isolate of Marek's disease, clusters of refractile rounded cells appeared consistently in the cell cultures. Intranuclear mature, immature, enveloped, and empty herpesvirus-type particles, usually associated with smaller particles, were observed in all rounded cells in the affected areas. Cytoplasmic inclusions containing mature enveloped virus particles were also seen in the rounded cells. Often fibroblasts growing in the vicinity of the cytopathic effect area contained a few herpesvirus-type particles. The original tumors prior to cultivation did not reveal any virus particles, and the virus in infected cultures was always cell-associated. Control cell cultures neither developed the rounded cells nor demonstrated the presence of any type of virus particles.

Isolation and characterization of viruses from the kidneys of Rana pipiens with renal adenocarcinoma before and after passage in the red eft (Triturus viridescens)

Viruses were isolated from kidneys of normal and renal tumor-bearing Vermont Rana pipiens after subinoculation into red eft newts (Triturus viridescens). Organs of efts inoculated with viable cell suspensions from four of seven tumor-bearing kidneys yielded virus (LT-1, -2, -3, -4) when inoculated into TH-1 (Terrapene heart) cell culture. One tumor-bearing kidney also yielded virus (L-4) by direct inoculation into TH-1 cells. An additional isolate (L-5) was obtained from 1 of 52 normal Vermont frog kidneys inoculated directly into TH-1 cells. LT-1 was propagated with cytopathic effect (CPE) in each of 38 cell types tested, of fish, amphibian, reptilian, avian, and mammalian origin, at 23 or 30 C. LT-1 through LT-4, L-4 and L-5, and FV-1 through FV-3 each induced similar CPE in all cells tested. LT-2, however, induced CPE that progressed at a slower rate than that caused by the other isolates and produced smaller plaques (<0.8 mm) under starch gel overlay. Each of the viruses replicated to high titer in embryonated eggs incubated at 30 C. The viruses also grew in efts and adult newts, but not in bullfrog (Rana catesbeiana) tadpoles or adult leopard frogs. Tumor induction in adult leopard frogs inoculated with LT-1 was not demonstrated. Electron microscopic observations of LT-1 and LT-2 viruses revealed cytoplasmic particles, hexagonal in cross section, approximately 120 to 140 mmu in diameter, containing a dense nucleoid. LT-1 and LT-2 viruses were indistinguishable from FV-1 and Tipula iridescent virus. LT-1 was presumed to be a deoxyribonucleic acid virus on the basis of 5-bromodeoxyuridine inhibition. The isolates were ether-sensitive. On the basis of biological, physicochemical, and antigenic similarities, LT-1 through LT-4, L-4, L-5, FV-1 through FV-3, and isolates recently recovered from the bullfrog and the newt may represent strains of the same amphibian cytoplasmic virus.

Electron microscopy of herpes simplex virus. II. Sequence of development

Examination of infected cells at sequential intervals after infection revealed that the first viral forms to appear were capsids enclosing cores of low density. Not until the 6th hr were dense cores encountered, and at approximately the same time enveloped virus was seen. Envelopment occurred most frequently in close proximity to the nuclear surface, although the process was also encountered within the nuclear matrix and in the cytoplasm. There was often extensive proliferation of the nuclear membrane. Envelopment of the virus by budding from the cell surface was not observed. It was concluded that enveloped virus consitutes the infectious particle and that the unenveloped capsid is unstable outside the cell. Nevertheless, it is likely that capsids enclosing infectious nucleic acid can pass directly from one cell to another after fusion has taken place.

HUMAN CYTOMEGALOVIRUS INFECTION. ELECTRON MICROSCOPIC AND HISTOCHEMICAL CHANGES IN CULTURES OF HUMAN FIBROBLASTS

Images

Evidence for a Persistent Viral Infection in a Cell Line Derived from Burkitt's Lymphoma

Henle, Gertrude (Children's Hospital of Philadelphia, Philadelphia, Pa.), and Werner Henle . Evidence for a persistent viral infection in a cell line derived from Burkitt's lymphoma. J. Bacteriol. 89: 252–258. 1965.—Exposure of a cell line (EB2) derived from Burkitt's lymphoma to vesicular stomatitis (VSV) and certain other viruses revealed a marked resistance of the cultures to infection. Intact, but not disintegrated lymphoma cells induced resistance to VSV in human embryonic kidney, amnion and diploid, as well as in green monkey kidney cells employed as feeder layers. A line of rabbit kidney or Earle's strain L cells was not protected under similar conditions. Depending upon the number of EB2 cells initially transferred, resistance developed within 1 day or in more than 2 weeks. Cell-free media collected from cultures of EB2 cells in the presence or absence of feeder layers of human cells were capable of conferring rapid protection against VSV to human-cell cultures but not to L cells. The protective principle complies with present criteria for an interferon. The results are compatible with the suggestion that EB2 cultures are latently infected with an as yet unidentified virus.