Production, Properties and Utility of Bacterial Minicells

Ac, Frazer; Curtiss, Roy

doi:10.1007/978-3-642-50112-8_1

Cited by 187 publications

(109 citation statements)

References 103 publications

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“…), they do not contain a chromosome, eliminating the possibility of pathogenic reversion in this approach. The ability of minicells to contribute to horizontal gene transfer to other pathogenic strains of bacteria is minimal as it has been well documented that bacterial mating into minicells is possible while the opposite is not [11,39,40].…”

Section: Discussionmentioning

confidence: 99%

“…Minicells were enriched by differential centrifugation and further purified by linear sucrose gradients as described previously [11] with LB broth containing 1 μg/mL ciprofloxacin substituted as the buffer. Minicell quantification was performed measuring A 600 and applying the equation: No.…”

Section: Minicell Isolationsmentioning

confidence: 99%

“…Minicells are small (100-400 nm), quazispherical, achromosomal bacterial particles that result from the disruption of the normal bacterial cell cycle [11,12]. Minicells contain many components of their parental cells including lipopolysaccharides (LPS), an intact peptidoglycan layer (cell wall), as well as any recombinantly expressed proteins and plasmid DNA molecules [11,[13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Immunization with non-replicating E. coli minicells delivering both protein antigen and DNA protects mice from lethal challenge with lymphocytic choriomeningitis virus

Giacalone

Zapata

Berkley

et al. 2007

Vaccine

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In the midst of new investigations into the mechanisms of both delivery and protection of new vaccines and vaccine carriers, it has become clear that immunization with delivery mechanisms that do not involve living, replicating organisms are vastly preferred. In this report, non-replicating bacterial minicells simultaneously co-delivering the nucleoprotein (NP) of lymphocytic choriomeningitis virus (LCMV) and the corresponding DNA vaccine were tested for the ability to generate protective cellular immune responses in mice. It was found that good protection (89%) was achieved after intramuscular administration, moderate protection (31%) was achieved after intranasal administration, and less protection (7%) was achieved following gastric immunization. These results provide a solid foundation on which to pursue the use of bacterial minicells as a non-replicating vaccine delivery platform.

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Section: Discussionmentioning

confidence: 99%

Section: Minicell Isolationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Immunization with non-replicating E. coli minicells delivering both protein antigen and DNA protects mice from lethal challenge with lymphocytic choriomeningitis virus

Giacalone

Zapata

Berkley

et al. 2007

Vaccine

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“…Under a variety of conditions bacteria do divide inappropriately at the junction region and produce small round DNA-less cells, called minicells (Adler et al, 1967 ;Frazer & Curtiss, 1974). This outcome can be favoured by mutations in minCD or in minE (de Boer e t al., 1989), but it can also be engineered by overproduction of theft.rZ gene product (Ward & Lutkenhaus, 1985).…”

Section: Formation Of Minicellsmentioning

confidence: 99%

A physical basis for the precise location of the division site of rod-shaped bacteria: the Central Stress Model

Koch

Höltje

1995

Microbiology

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There are difficulties with all published models that attempt to explain how rod-shaped bacteria locate their midpoint in preparation for the next cell division. Many bacteria find their middle quite accurately. This evenness of partition has been measured cytologically and is implied by the persistence of synchrony under certain circumstances. Previously, a number of models for the control of cell division have been proposed based on aspects of molecular genetics, ultrastructure measurements, or biochemical kinetics. This paper points out that none of the models in spite of their quite different natures can explain the precision of the location of the division site. Here, the 'Central Stress Model' is proposed which depends on the partition of wall tension between the cytoplasmic membrane (CM) and the murein layer in such a way that the CM at the centre of the rod experiences a higher stress than near the poles and that this peak stress increases through the cell cycle. The model assumes that: (i) murein is not incorporated at an established pole but is incorporated diffusely over the sidewall and intensely at sites of cell constriction; (ii) C M is synthesized over the entire cell wall; (iii) the murein and C M layers are attached non-covalently to each other, and interact physically with each other; (iv) this differential location of synthesis leads to a 'tug-ofwar' that creates differential stresses that peak at the cell centre. Because of the fluid nature of the phospholipid bilayer there is a flux of lipid from the established poles towards the cell centre as the murein sidewall elongates. The flux from the pole lowers the tension in the C M at the ends of the sidewalls and creates a peak tension in the centre. Cells also have a discontinuity in the stresses in the murein at the junction of the curved pole with the cylindrical region of the cell wall (a doubling of the hoop stress above the axial stress). Thus in addition to the midpoint of the cell, these junctions between the polar caps and the cylindrical part of the cell wall are characterized by an abrupt change in the surface stress and we suggest that this can trigger cell division at these junctions to form a chromosome-less minicell. Two other assumptions of the model are that the cell has a membrane-associated system to sense the stress, and to trigger cell division locally when a threshold has been reached. It is suggested that there is a special twolcomponent sensory system responding to tension in the CM. As the cell cycle progresses, and the stress in the centre of the cell exceeds some threshold, a system molecule triggers a cell division event at that site. Like other two-component systems, the sensory component of this two-component system is assumed to be distributed all over the CM. It is also assumed that when the sensory component is triggered it also causes local changes that ensure that division occurs at that site. Consequently, this model can explain why sister cells have very nearly the same size (length, volume, or biomass) and w...

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“…Purification of crude preparations has been carried out by sedimentation in gradients of glycerol (Wickner et al, 1972) or sucrose (Adler et al, 1967;Inselburg, 1970;Reeve et al, 1973). Membrane filtration has also been used, but it is reported that this results in low yields (Frazer & Curtiss, 1973). To increase the efficiency of the removal of nucleated cells, such cells have been partially destroyed by induction of a lysogenic phage (Kass & Yarmolinsky, 1970) and by sonication and treatment with penicillin (Khachatourians & Saunders, 1973).…”

Section: Introductionmentioning

confidence: 99%

Isolation by Differential and Zonal Centrifugation of Minicells Segregated by Escherichia coli

Barker¹,

Cordery²,

Jackson³

et al. 1979

Journal of General Microbiology

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387Minicells segregated from Escherichia coli ~9 2 5 carrying a drug-resistance plasmid were separated from nucleated cells by differential centrifugation and purified by rate-zonal centrifugation in sucrose gradients. Minicells purified in this way were capable of donating the plasmid to nucleated cells. They also incorporated thymidine, uridine and methionine into macromolecules. Methods are described for purification of plasmid-containing minicells on a scale large enough to allow isolation of DNA, DNA polymerase and RNA polymerase in sufficient quantities for studies of enzymes involved in replication and transcription of plasmid DNA. I N T R O D U C T I O NIn connection with studies on the expression of plasmid-borne genes in enterobacteria, it became necessary to prepare relatively large quantities of plasmid DNA, DNA polymerases and RNA polymerases. Plasmid DNA can be separated from chromosomal DNA and characterized by making use of its superhelical nature and its resistance to denaturation or, after transfer into a heterologous recipient, by virtue of the difference in buoyant density between host and plasmid DNA. Using any of these methods, radioactively labelled plasmid DNA is readily characterized on a very small scale although isolation on a preparative scale is more difficult. Isolation of enzymes associated with plasmid replication and transcription also presents difficulties. Not only is it necessary to prepare enzymes in sufficient quantity for purification and assay of activity, but, in addition, there are no clear criteria for the recognition of enzymes specifically associated with the plasmid. Humphreys et al. (1975) have described a method for preparation of large quantities of plasmid DNA by precipitation with polyethylene glycol from cleared lysates of bacteria prepared by the method of Clewell & Helinski (1969). However, this method is not readily adapted to the isolation of plasmid-associated enzymes.The discovery that plasmids may segregate into minicells during cell division (Kass & Yarmolinsky, 1970) offers an alternative method of separating plasmid DNA from chromosomal DNA in minicell-segregating strains. Moreover, it has been shown that both DNA polymerase and RNA polymerase activities are present in plasmid-containing minicells (Hurwitz & Gold, cited by Cohen et al., 1968a). It has also been demonstrated that such minicells are capable of protein synthesis (Fralick et al., 1969;Levy, 1974;Levy et al., 1974). However, it is probable that only a limited number of enzymes are synthesized. Moreover, the possibility of radioactively labelling enzymes coded for by plasmid genes does not obviate the difficulty of preparing sufficient material for enzymic assays.Partial separation of minicells from nucleated cells is normally achieved by differential centrifugation (Cohen et al., 19683). Purification of crude preparations has been carried out by sedimentation in gradients of glycerol (Wickner et al., 1972) or sucrose (Adler et al., 1967;Inselburg, 1970;Reeve et al., 1973). Membrane filtrat...

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Production, Properties and Utility of Bacterial Minicells

Cited by 187 publications

References 103 publications

Immunization with non-replicating E. coli minicells delivering both protein antigen and DNA protects mice from lethal challenge with lymphocytic choriomeningitis virus

Immunization with non-replicating E. coli minicells delivering both protein antigen and DNA protects mice from lethal challenge with lymphocytic choriomeningitis virus

A physical basis for the precise location of the division site of rod-shaped bacteria: the Central Stress Model

Isolation by Differential and Zonal Centrifugation of Minicells Segregated by Escherichia coli

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