Structural analysis of some Escherichia coli capsular antigens
- Authors: Hackland, Peter Linton
- Date: 1992
- Subjects: Antigens , Enterobacteriaceae , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3758 , http://hdl.handle.net/10962/d1003236 , Antigens , Enterobacteriaceae , Escherichia
- Description: The work presented in this thesis forms part of a collaborative effort to determine the chemical structures of the surface antigens of bacteria which belong to the Enterobacteriaceae. These antigens are largely polysaccharides and occur as lipopolysaccharides and capsular polysaccharides which give rise to the somatic or 0 antigens and the capsular or K antigens, respectively. In recent years interest has mostly been focused on the extracellular polysaccharide antigens expressed by the genus Escherichia coli because of the effect they exert on normal immunological processes and their structural relatedness to the surface antigens of other more pathogenic bacteria. Therefore the molecular structures of the capsular polysaccharides (Kantigens)produced by E. coli 09:K35(AI04a) and 09:K38(A262a) have been determined by novel enzymic, chemical and spectroscopic procedures. These investigations show that the structures of these polysaccharides can be determined by a combination of chemical and spectroscopic procedures , or almost entirely by n.m.r. spectroscopy alone. The in vitro bacteriophage mediated depolymerisation of the native E. coli K35 polysaccharide demonstrates the value of this method for the isolation of oligosaccharides representing the repeating- unit and multiples thereof. Finally E. coli K37 and K38 capsular polysaccharides were used as model compounds for the evaluation of partial and selective reductive cleavage as methods of generating oligosaccharide for further structural analysis. The products of these reactions were analysed largely by a combination of mass spectrometric procedures.
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- Date Issued: 1992
Chemical and spectroscopic studies of the capsular polysaccharides of some klebsiella and escherichia coli serotypes
- Authors: Stanley, Shawn Mark Ross
- Date: 1990
- Subjects: Polysaccharides , Klebsiella , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3736 , http://hdl.handle.net/10962/d1001525
- Description: The work described in this thesis forms part of an international programme concerned with the structure elucidation of the capsular antigens of some Enterobacteriaceae. Many of the Klebsiella and some of the Escherichia coli are pathogenic to man and, hence, they are of interest. The virulence of bacteria is a multifactorial phenomenon, in which characteristic traits of bacteria and their hosts play comparable and complementary roles. It is accepted that pathogens are more virulent when encapsulated, because, nearly all disease causing bacteria have a capsule when freshly isolated from the host. This increase in pathogenicity is related, in part, to the capsular polysaccharides' ability to avoid or attenuate the host defence mechanisms. In the majority of cases the protective aspects of the capsule are overcome in the latter stages of infection when the formation of specific antibodies by the host has occurred. However there are situations in which an immune state of the infected host is virtually never reached, and susceptiblity to the infecting bacteria is maintained even in the advanced stage of an infection. Explanation of this phenomenon becomes possible by analysing the structure of the polysaccharides. The inability of the host to raise an immune response to the capsule may be because the structure of the polysaccharide is similar or identical to the host's carbohydrates. The serological and pathogenic relatedness of encapsulated E. coli and Klebsiella, to the encapsulated strains of other genera, is based on structural identity or similarity of the respective capsules. Capsular polysaccharides are analysed by both chemical and instrumental methods, and, at present, nuclear magnetic resonance spectroscopy is the most important analytical technique
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- Date Issued: 1990
Structural studies on some capsular antigens from escherichia coli and klebsiella
- Authors: Anderson, Andrew Nixon
- Date: 1988
- Subjects: Escherichia , Klebsiella , Antigens
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3730 , http://hdl.handle.net/10962/d1001469
- Description: A review of the structural studies of bacterial capsular polysaccharides (K-antigens) from Escherichia coli and Klebsiella, and of the trends in modern chemical and instrumental techniques available for the analysis of carbohydrate material is presented. The structural elucidations of the capsular polysaccharides from E. coli K37 and K55, and Klebsiella K39 are reported with comments on the novelty and possible immunological significance of the structures. The usefulness of the bacteriophage degradation technique has been emphasized using the polysaccharides from E. coli K55, and Klebsiella K30 and K39 to demonstrate the scope of the reaction
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- Date Issued: 1988