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Biomedical subjects

I Charles

Publications and source records attributed to I Charles.

27 records · Page 2Linked to original sources
PubMed1991

Insertional inactivation of the Staphylococcus aureus beta-toxin by bacteriophage phi 13 occurs by site- and orientation-specific integration of the phi 13 genome.

Lysogenization of Staphylococcus aureus by the serotype F converting bacteriophage phi 13 results in loss of beta-toxin expression. Sequence analysis of the S. aureus beta-toxin gene (hlb), the attachment site (attP)-containing region of phi 13 DNA and the chromosome/bacteriophage DNA junctions of a phi 13 lysogen, revealed that the molecular mechanism of loss of beta-toxin expression was due to insertion of the phi 13 genome into the 5' end of hlb. The insertion site (attB) within hlb contained a 14 base pair core sequence in common with attP and both ends of the integrated linear prophage genome of a phi 13 lysogen. These findings indicate that integration of the phi 13 genome into hlb is site- and orientation-specific.

Amino Acid Sequence↗
PubMed1991

The role of a stress-response protein in Salmonella typhimurium virulence.

We recently described the use of selective transposon mutagenesis to generate a series of avirulent mutants of a pathogenic strain of Salmonella typhimurium. Cloning and sequencing of the insertion sites from two of these mutants reveals that both have identical locations within an open reading frame that is highly homologous to a gene, htrA, encoding a heat-shock protein in Escherichia coli. DNA sequence analysis of S. typhimurium htrA reveals the presence of a gene capable of encoding a protein with a calculated Mr of 49316 that has 88.7% protein:protein homology with its E. coli counterpart. In E. coli, lesions in this gene, also known as degP, reduce proteolytic degradation of aberrant periplasmic proteins. Characteristics of the S. typhimurium htrA mutants, 046 and 014, in vivo and in vitro suggested that they are avirulent because of impaired ability to survive and/or replicate in host tissues. In vitro, the S. typhimurium htrA mutants 046 and 014 are not temperature-sensitive but were found to be more susceptible to oxidative stress than the parent, suggesting that they may be less able to withstand oxidative killing within macrophages.

Alkaline Phosphatase↗
PubMed1990

Gene expression and the development of live enteric vaccines.

Rationally attenuated live Salmonella vaccines provide good protection against homologous challenge and can act as carriers of heterologous antigens. However, the optimum expression system for each heterologous antigen will need to be established individually. This will ensure that the antigen in question is produced at appropriate levels, in the correctly folded conformation, within or at the surface of the carrier cell, and can therefore elicit the optimal immune response.

Animals↗
PubMed1990

Cloning and characterization of the aroA gene from Mycobacterium tuberculosis.

The aroA gene from Mycobacterium tuberculosis has been cloned by complementation of an aroA mutant of Escherichia coli after lysogenization with a recombinant DNA library in the lambda gt11 vector. Detailed characterization of the M. tuberculosis aroA gene by nucleotide sequencing and by immunochemical analysis of the expressed product indicates that it encodes a 5-enolpyruvylshikimate-3-phosphate synthase that is structurally related to analogous enzymes from other bacterial, fungal, and plant sources. The potential use of the cloned gene in construction of genetically defined mutant strains of M. tuberculosis by gene replacement is proposed as a novel approach to the rational attenuation of mycobacterial pathogens and the possible development of new antimycobacterial vaccines.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed1988

Oral vaccination.

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Administration, Oral↗
PubMedDate not supplied

Expression of P.69/pertactin from Bordetella pertussis in a baculovirus/insect cell expression system: protective properties of the recombinant protein.

The surface antigen P.69/pertactin of Bordetella pertussis has been expressed using the polyhedron promoter of baculovirus in cultured insect cells. Either full-length or truncated prn DNA was used to express P.69 pertactin. The full-length gene gave rise to low levels of P.93 precursor protein, some of which was processed to P.69. The shortened prn expressed P.69 pertactin directly at levels up to 3.5 mg per litre. P.69 vaccinated animals were protected against aerosol challenge with virulent B. pertussis bacteria.

Animals↗