PubMed Health⌕ Search

Biomedical subjects

J Yeadon

Publications and source records attributed to J Yeadon.

6 recordsLinked to original sources
PubMed1991

Construction of plasmid vectors with a non-antibiotic selection system based on the Escherichia coli thyA+ gene: application to cholera vaccine development.

The construction of live oral carriers based on attenuated Salmonella strains as vectors offers a new approach to vaccine development. We have constructed a set of plasmid vectors which have the thyA gene of Escherichia coli (encoding thymidylate synthetase) as the marker for selection and maintenance of plasmid clones. The thyA system offers an alternative to antibiotic-resistance selection markers. It can be easily adapted to a particular host-vector combination since thyA chromosomal mutations can be readily introduced by trimethoprim selection. We also describe the construction of thyA-based plasmids with the Vibrio cholerae rfb genes (encoding O-antigen biosynthesis of the Inaba serotype). These have been found to be useful in the construction of candidate bivalent cholera-typhoid vaccines.

Antigens, Bacterial↗
PubMed1991

Effect of lipopolysaccharide core synthesis mutations on the production of Vibrio cholerae O-antigen in Escherichia coli K-12.

The rfb genes of Vibrio cholerae O1 (Ogawa serotype) were subcloned into a derivative of pBR322. This plasmid was transformed into several Escherichia coli K-12 mutant strains which produce an incomplete lipopolysaccharide (LPS)-core-oligosaccharide region. The data indicate that the V. cholerae O-antigen is assembled onto the E. coli LPS and that at least two glucoses are needed in the core in order to achieve a high level of production. These data are consistent with the reported presence of glucose in the V. cholerae LPS-core-oligosaccharide region.

Antigens, Bacterial↗
PubMed1987

A physical map of the chromosomal region determining O-antigen biosynthesis in Vibrio cholerae O1.

We have previously described the cosmid cloning of the genes determining the biosynthesis of the Inaba and Ogawa O-antigens of the lipopolysaccharides of Vibrio cholerae O1 (Manning et al., 1986). By Southern hybridization analysis of chromosomal and cosmid DNA, and heteroduplex analysis between the clones we have been able to precisely define the region of contiguous chromosomal DNA in the vicinity of the O-antigen-encoding region. These data and comparison of end points of clones and of deletion derivatives demonstrate that at least 16 kb of a 19-kb SstI fragment is required to encode O-antigen biosynthesis. Expression of O-antigen is independent of the orientation of this SstI fragment with respect to cloning vectors suggesting that its regulatory region has been cloned intact. No detectable differences were observed in the restriction patterns of the Inaba and Ogawa coding regions implying that only minor changes are involved when serotype conversion (Inaba to Ogawa or vice versa) occurs. Bhaskaran [Ind. J. Med. Res. 47 (1959) 253-260] originally defined this region associated with O-antigen biosynthesis oag; however, to be consistent with other organisms [Hitchcock et al., J. Bacteriol. 166 (1986) 699-705], it is suggested this be changed to rfb.

Antigens, Bacterial↗
PubMed1986

Molecular cloning and expression in Escherichia coli K-12 of the O antigens of the Inaba and Ogawa serotypes of the Vibrio cholerae O1 lipopolysaccharides and their potential for vaccine development.

The gene clusters that determine the biosynthesis of both the Inaba and Ogawa serotypes of the O antigen of the lipopolysaccharide of Vibrio cholerae were cloned and expressed in Escherichia coli K-12. Restriction analysis of the clones demonstrated that about 15 kilobases were common to all clones and a further 5 kilobases were common to the Ogawa clones. The O antigens expressed by E. coli K-12 had the specificity of V. cholerae. Antibodies raised against E. coli K-12 that harbor one of these clones, pPM1001 (Inaba), were as highly protective in the infant mouse model system as were antibodies to V. cholerae itself. Introduction of such clones into suitable carrier strains could be expected to produce a good oral immunogen against cholera.

Animals↗
PubMed1976

Fergus.

Explore the source record for details and available documents.

Public Health Nursing↗