Electron microscope study of mouse liver infected by ectromelia virus

Leduc, Elizabeth H.; Waldenfels, Bernhard

doi:10.1016/s0022-5320(62)80003-3

Cited by 34 publications

(9 citation statements)

References 30 publications

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“…1). Similar ultrastructural changes were reported by Leduc & Bernhard (1962) in infected liver cells in mice suffering from mousepox.…”

Section: Microscopical Observationssupporting

confidence: 87%

“…1) was indistinguishable from that of ectromelia virus in infected mouse livers (Leduc & Bernhard, 1962) or that of other poxviruses (Moss, 1974). In contrast, the response of the cells was significantly different to that normally seen in a wide range of poxvirus-infected tissue culture cells, but remarkably similar to that observed in ectromelia virus-infected mouse livers.…”

Section: Discussionmentioning

confidence: 65%

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Ectromelia Virus-induced Changes in Primary Cultures of Mouse Hepatocytes

Lees

Stephen

1985

Journal of General Virology

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SUMMARYMouse hepatocytes were isolated by collagenase perfusion, maintained in nonproliferating monolayer culture and shown to retain liver cell function as judged by gluconeogenesis for 15 to 18 h. Such cells could be infected with and support the replication of a virulent strain of ectromelia virus. Virus antigen and characteristic cytoplasmic 'B'-type poxvirus inclusion bodies were demonstrated by immunofluorescence in virtually all cells. By electron microscopy it was shown that 'B'-type inclusions were the site of virus replication, and that the biogenesis of ectromelia virus and ultrastructural changes in hepatocytes were similar to those observed in infected mouse livers. Early cell rounding effects, a normal characteristic of poxvirus infections in tissue culture cells, were not seen in ectromelia-infected hepatocytes, although late degenerative changes did occur. Pulse-labelling of hepatocyte cultures with [35S]methionine showed that ectromelia virus inhibited the rise in protein synthesis seen in controls and imposed a gradual decline in host protein synthesis to an extent and at a rate significantly different from that in mouse L929 cells. Gluconeogenesis was inhibited by ectromelia virus infection of hepatocytes.

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“…1). Similar ultrastructural changes were reported by Leduc & Bernhard (1962) in infected liver cells in mice suffering from mousepox.…”

Section: Microscopical Observationssupporting

confidence: 87%

Section: Discussionmentioning

confidence: 65%

Ectromelia Virus-induced Changes in Primary Cultures of Mouse Hepatocytes

Lees

Stephen

1985

Journal of General Virology

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“…Important and still unresolved issues about VV assembly are how the full complement of proteins become wrapped by the viral membrane to generate individual spherical IVs and how the genomic DNA is incorporated into these particles. Several studies suggested that the viral DNA packed into a nucleoprotein complex is taken up before the IVs are completely sealed (13,18,28,31).…”

Section: Discussionmentioning

confidence: 99%

The Major Core Protein P4a (A10L Gene) of Vaccinia Virus Is Essential for Correct Assembly of Viral DNA into the Nucleoprotein Complex To Form Immature Viral Particles

Heljasvaara¹,

Rodrı́guez²,

Risco

et al. 2001

J Virol

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The vaccinia virus (VV) A10L gene codes for a major core protein, P4a. This polypeptide is synthesized at late times during viral infection and is proteolytically cleaved during virion assembly. To investigate the role of P4a in the virus life cycle and morphogenesis, we have generated an inducer-dependent conditional mutant (VVindA10L) in which expression of the A10L gene is under the control of the Escherichia coli lacI operator/ repressor system. Repression of the A10L gene severely impairs virus growth, as observed by both the inability of the virus to form plaques and the 2-log reduction of viral yields. This defect can be partially overcome by addition of the inducer isopropyl-␤-D-thiogalactopyranoside (IPTG). Synthesis of viral proteins other than P4a occurred, although early shutoff of host protein synthesis and expression of viral late polypeptides are clearly delayed, both in the absence and in the presence of IPTG, compared with cells infected with the parental virus. Viral DNA replication and concatemer resolution appeared to proceed normally in the absence of the A10L gene product. In cells infected with VVindA10L in the absence of the inducer virion assembly is blocked, as defined by electron microscopy. Numerous spherical immature viral particles that appear devoid of dense viroplasmic material together with highly electron-dense regular structures are abundant in VVindA10L-infected cells. These regularly spaced structures can be specifically labeled with anti-DNA antibodies as well as with a DNase-gold conjugate, indicating that they contain DNA. Some images suggest that these DNA structures enter into spherical immature viral particles. In this regard, although it has not been firmly established, it has been suggested that DNA uptake occurs after formation of spherical immature particles. Overall, our results showed that P4a and/or its cleaved products are essential for the correct assembly of the nucleoprotein complex within immature viral particles.Vaccinia virus (VV), the prototype member of the Poxviridae family, is a large DNA virus whose replication and assembly occur entirely in the cytoplasm of the host cell, in particular areas termed viral factories or virosomes (33). The linear double-stranded DNA genome has a capacity to encode over 200 polypeptides (22), of which approximately 100 are incorporated into virus particles (14). The viral genes can be divided into three classes according to their temporally regulated expression. The early genes are transcribed prior to DNA replication, while the intermediate and late genes are transcribed only during or after replication of the viral genome (33).Detailed information about VV morphogenesis has been obtained from studies by conventional electron microscopy (6, 7, 9, 21, 31, 32). Virus assembly begins within cytoplasmic viral factories with the formation of crescent-shaped membranes whose origin remains controversial. These membranes subsequently enclose granular material from the virosomes, forming spherical particles known as immature vir...

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“…These inclusions have been described before in SPV infections (4,5,22,23) as well as in infections induced by other pox viruses (cf. 4,13). Their exact role in the process of virus replication and/or development has not yet been explained.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural aspects of experimental swinepox with special reference to inclusion bodies

Teppema

Boer

1975

Archives of Virology

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A light and electron microscopic study was performed on pox-like epidermal lesions in an experimentally infected pig. Light microscopical investigation of semithin sections revealed the presence of nuclear vacuoles and of different types of cytoplasmic inclusions. In electron microscopical studies large numbers of both immature and mature virus particles and the cytological changes indicative of pox virus infection were observed. Various types of intra-cytoplasmic inclusions -- i.e. fibrillar inclusions, crystalloid-containing dense inclusions, complex membraneous inclusions and dense homogeneous inclusions -- were encountered in addition to viroplasms and nuclear vacuoles. Because of the presence of vacuoles in nuclei of stratum spinosum cells the diagnosis swine pox by swinepox virus was most probable. These nuclear vacuoles have not been described in swine pox caused by vaccinia virus, the only other known cause of pox in swine.

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Electron microscope study of mouse liver infected by ectromelia virus

Cited by 34 publications

References 30 publications

Ectromelia Virus-induced Changes in Primary Cultures of Mouse Hepatocytes

Ectromelia Virus-induced Changes in Primary Cultures of Mouse Hepatocytes

The Major Core Protein P4a (A10L Gene) of Vaccinia Virus Is Essential for Correct Assembly of Viral DNA into the Nucleoprotein Complex To Form Immature Viral Particles

Ultrastructural aspects of experimental swinepox with special reference to inclusion bodies

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