Ultrastructural, cytochemical, and microchemical observations on cytomegalovirus (salivary gland virus) infection of human cells in tissue culture

McGavran, Malcolm H.; Smith, Margartt G.

doi:10.1016/0014-4800(65)90019-5

Cited by 112 publications

(46 citation statements)

References 14 publications

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“…The tubular structures observed in the GPCMV infected cells appeared to be a distinctive characteristic of GPCMV induced changes in cultured cells. Similar structures were not seen in human cytomegalovirus infected human cells (McGavran & Smith, 1965;Ruebner et al I965;Iwasaki et al I973) nor murine cytomegalovirus infected mouse cells (Luse & Smith,I958). From the data obtained in the chemical inhibition experiments, synthesis of the tubular structures did not require DNA synthesis but was dependent upon de novo protein synthesis; it is likely that the tubular structures were protein in nature.…”

Section: Discussionmentioning

confidence: 76%

Ultrastructural Development of Guinea Pig Cytomegalovirus in Cultured Guinea Pig Embryo Cells

Fong

Bia

Hsiung

et al. 1979

Journal of General Virology

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SUMMARYThe ultrastructural development of guinea pig cytomegalovirus (GPCMV) in guinea pig embryo cells was studied using electron microscopy. Tubular structures were found in nuclei of virus infected cells, followed by the appearance of intranuclear inclusions containing virus nucleocapsids. While some nucleocapsids were enveloped at the inner nuclear membrane, others were released into the cytoplasm where they were associated with, or within, dense matrix which was subsequently enveloped by cytoplasmic membranes to form enveloped dense virions. Dense bodies without virus capsids were formed in the cytoplasm and enveloped in a similar manner. An involvement of the nuclear pores in the release of unenveloped virus capsids from the nucleus to the cytoplasm was postulated. Evidence that the enveloped dense virions and dense bodies shared common envelope antigen(s) was obtained by immunoelectron microscopy. The similarities and differences in the ultrastructuraI development of GPCMV and other cytomegaloviruses are discussed.

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Section: Discussionmentioning

confidence: 76%

Ultrastructural Development of Guinea Pig Cytomegalovirus in Cultured Guinea Pig Embryo Cells

Fong

Bia

Hsiung

et al. 1979

Journal of General Virology

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“…Similar structures have been observed in infected cultured primary fibroblasts, endothelial cells, and smooth muscle cells (21,24). One side of the structure has a perinuclear localization, with the nucleus taking on a kidney-like shape as it bends partially around the AC (20,25,34,59). Electron microscopic evidence indicates that the AC is in a highly vacuolated part of the cytoplasm and is the site of final tegumentation and envelope acquisition (20,50,51,54,57).…”

mentioning

confidence: 62%

“…Exactly how virions mature in the AC has remained a mystery. Early ultrastructural analyses indicated that nucleocapsids could acquire an envelope at the inner nuclear membrane and at cytoplasmic vesicles, but the relationship between the processes was not understood (25,28,34,45,54). Severi and coworkers (39,50,51) were the first to propose that HCMV nucleocapsids acquire an envelope during the process of budding from the inner nuclear membrane to the lumen of the nuclear membrane and then lose that envelope upon "infecting" the cytoplasm.…”

Section: Discussionmentioning

confidence: 99%

Three-Dimensional Structure of the Human Cytomegalovirus Cytoplasmic Virion Assembly Complex Includes a Reoriented Secretory Apparatus

Das¹,

Vasanji

Pellett³

2007

J Virol

178

235

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Human cytomegalovirus (HCMV) induces profound changes in infected cell morphology, including a large cytoplasmic inclusion that corresponds to the virion assembly complex (AC). In electron micrographs, the AC is a highly vacuolated part of the cytoplasm. Markers of cellular secretory organelles have been visualized at the outer edge of the AC, and we recently showed that a marker for early endosomes (i.e., early endosome antigen 1) localizes to the center of the AC. Here, we examined the relationship between the AC and components of the secretory apparatus, studied temporal aspects of the dramatic infectioninduced cytoplasmic remodeling, examined the three-dimensional structure of the AC, and considered the implications of our observations for models of HCMV virion maturation and egress. We made three major observations. First, in addition to being relocated, the expression levels of some organelle markers change markedly during the period while the AC is developing. Second, based on three-dimensional reconstructions from z-series confocal microscopic images, the observed concentric rings of vesicles derived from the several compartments (Golgi bodies, the trans-Golgi network [TGN], and early endosomes) are arranged as nested cylinders of organelle-specific vesicles. Third, the membrane protein biosynthetic and exocytic pathways from the endoplasmic reticulum to the Golgi bodies, TGN, and early endosomes are in an unusual arrangement that nonetheless allows for a conventional order of biosynthesis and transport. Our model of AC structure suggests a mechanism by which the virus can regulate the order of tegument assembly.

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“…(ii) In contrast to the symmetrical, "double-ringed," well-defined intranuclear capsids typical of wild-type infected cells (24), intranuclear capsids in cells infected with the L47A mutant were comparatively irregular in shape; many lacked an "inner ring," and some appeared cracked or breaking apart ( Fig. 5A and B).…”

mentioning

confidence: 97%

The Amino-Conserved Domain of Human Cytomegalovirus UL80a Proteins Is Required for Key Interactions during Early Stages of Capsid Formation and Virus Production

Loveland

Nguyen

Brignole

et al. 2007

J Virol

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Assembly of many spherical virus capsids is guided by an internal scaffolding protein or group of proteins that are often cleaved and eliminated in connection with maturation and incorporation of the genome. In cytomegalovirus there are at least two proteins that contribute to this scaffolding function; one is the maturational protease precursor (pUL80a), and the other is the assembly protein precursor (pUL80.5) encoded by a shorter genetic element within UL80a. Yeast GAL4 two-hybrid assays established that both proteins contain a carboxyl-conserved domain that is required for their interaction with the major capsid protein (pUL86) and an amino-conserved domain (ACD) that is required for their self-interaction and for their interaction with each other. In the work reported here, we demonstrate that when the ACD is deleted (␦ACD) or disrupted by a point mutation (L47A), the bacterially expressed mutant protein sediments as a monomer during rate-velocity centrifugation, whereas the wild-type protein sediments mainly as oligomers. We also show that the L47A mutation reduces the production of infectious virus by at least 90%, results in the formation of irregular nuclear capsids, gives rise to tube-like structures in the nucleus that resemble the capsid core in cross-section and contain UL80 proteins, slows nuclear translocation of the major capsid protein, and may slow cleavage by the maturational protease. We provide physical corroboration that mutating the ACD disrupts self-interaction of the UL80 proteins and biological support for the proposal that the ACD has a critical role in capsid assembly and production of infectious virus.A common feature among viruses with a spherical capsid is their use of a transient internal scaffolding structure to coordinate assembly of the capsid shell (7,11,13,17,32). Among the herpes group viruses this scaffold is made up of at least two essential proteins. These are encoded by UL80a and UL80.5 in human cytomegalovirus (HCMV) (17,38,39) and have counterparts in the other herpesviruses (12,22,36,39). UL80a, the longer of the two CMV open reading frames (ORFs), specifies the 74-kDa viral maturational protease precursor (pPR), and contains genes for three additional independently synthesized proteins. All four are in frame and carboxy coterminal, such that the amino acid sequence of the smaller proteins is identical to the sequence of the carboxyl end of the larger proteins (22, 39), as illustrated in Fig. 1. UL80.5 specifies the most abundant of the UL80 proteins, which is called the assembly protein precursor (pAP) and is the core component of the scaffold.The requirement for these proteins during capsid formation and maturation has been demonstrated by using mutant viruses (10, 15, 29, 41) and a recombinant-baculovirus herpes simplex virus (HSV) capsid assembly system (33, 34). In the absence of a pAP homolog (i.e., HSV pUL26.5 or preVP22a), the formation of closed spherical capsids is disrupted, and aberrantly shaped particles accumulate in the nucleus without forming infectiou...

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Ultrastructural, cytochemical, and microchemical observations on cytomegalovirus (salivary gland virus) infection of human cells in tissue culture

Cited by 112 publications

References 14 publications

Ultrastructural Development of Guinea Pig Cytomegalovirus in Cultured Guinea Pig Embryo Cells

Ultrastructural Development of Guinea Pig Cytomegalovirus in Cultured Guinea Pig Embryo Cells

Three-Dimensional Structure of the Human Cytomegalovirus Cytoplasmic Virion Assembly Complex Includes a Reoriented Secretory Apparatus

The Amino-Conserved Domain of Human Cytomegalovirus UL80a Proteins Is Required for Key Interactions during Early Stages of Capsid Formation and Virus Production

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