How do bacteria decide where to divide?
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Bacillus subtilis↗
Biomedical subjects
C R Zhao
Publications and source records attributed to C R Zhao.
Proper placement of the Escherichia coli division site requires two functions that are associated with different domains of the MinE protein.
The proper placement of the Escherichia coli division septum requires the MinE protein. MinE accomplishes this by imparting topological specificity to a division inhibitor coded by the minC and minD genes. As a result, the division inhibitor prevents septation at potential division sites that exist at the cell poles but permits septation at the normal division site at midcell. In this paper, we define two functions of MinE that are required for this effect and present evidence that different domains within the 88-amino acid MinE protein are responsible for each of these two functions. The first domain, responsible for the ability of MinE to counteract the activity of the MinCD division inhibitor, is located in a small region near the N terminus of the protein. The second domain, required for the topological specificity of MinE function, is located in the more distal region of the protein and affects the site specificity of placement of the division septum even when separated from the domain responsible for suppression of the activity of the division inhibitor.
Adenosine Triphosphatases↗
Safety and immunogenicity study of the auxotrophic Shigella flexneri 2a vaccine SFL1070 with a deleted aroD gene in adult Swedish volunteers.
The live auxotrophic Shigella flexneri 2a vaccine strain SFL1070 with a deleted aroD gene was given orally to 37 adult Swedish volunteers who received three doses within 5 days. Each dose comprised 1 x 10(5) (n = 9), 1 x 10(7) (n = 10), 1 x 10(8) (n = 9) or 1 x 10(9) (n = 9) c.f.u. S. flexneri SFL1070. One volunteer vaccinated with 1 x 10(7) and three vaccinated with 1 x 10(8) c.f.u. reported mild gastrointestinal symptoms after the first dose. Vaccination with 1 x 10(9) c.f.u. caused abdominal pain and watery diarrhoea in four volunteers who all recovered spontaneously within 72 h. S. flexneri SFL1070 was not recovered from volunteers given 1 x 10(5) c.f.u., but was shed in faeces by six volunteers vaccinated with 1 x 10(7), by all nine vaccinated with 1 x 10(8), and by seven volunteers vaccinated with 1 x 10(9) c.f.u. The mean excretion time was 2.6 (range 0-4) days in the 1 x 10(8) and the 1 x 10(9) groups. Serum antibody responses against either S. flexneri 2a and Y lipopolysaccharides (LPSs) or Shigella invasion plasmid antigens (Ipa) were seen in eight volunteers vaccinated with 1 x 10(9) (p < 0.01 to p < 0.05 for mean relative titres of IgA and IgG against S. flexneri 2a and Y LPSs), in four vaccinated with 1 x 10(8), and in two and one volunteers each vaccinated with 1 x 10(7) and 1 x 10(5) c.f.u. of S. flexneri SFL1070. Intestinal sIgA responses to the same antigens were elicited in all volunteers in the 1 x 10(9) and the 1 x 10(8) groups, and in six and one volunteers vaccinated with 1 x 10(7) and 1 x 10(5) c.f.u., respectively. The sIgA responses against S. flexneri 2a and Y LPSs were significant in all but the 1 x 10(5) group (p < 0.01 to p < 0.05). Significant antibody-secreting cell (ASC) responses specific to S. flexneri 2a LPS were seen in peripheral blood from eight volunteers each in the 1 x 10(9) and 1 x 10(8) groups and from five volunteers vaccinated with 1 x 10(7) c.f.u. (p < 0.01 to p < 0.05). The number of volunteers showing anti-Shigella Ipa ASC responses in these groups were five (p < 0.01 to p < 0.05), three and one, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
Administration, Oral↗
Serum IgG antibody responses to Shigella invasion plasmid-coded antigens detected by immunoblot.
Serum IgG antibody responses to Shigella invasion plasmid-coded antigens (Ipa) from 58 Shigella flexneri, S. sonnei, and S. dysenteriae infected Swedish patients were investigated by immunoblot technique. Intense responses to most components of Ipa (Ipas A, B, C, D, and VirG-virulence determinant on SalI fragment G of the plasmid) were evident in sera from S. flexneri infected patients. The strongest response was to Ipa B and the weakest, to Ipa D. In contrast, there were weaker responses to Ipas A, B, C, and VirG but none at all to Ipa D in sera from S. sonnei infected patients. After absorption of the Ipa-positive sera by Ipa expressing strains of S. flexneri and S. sonnei, most IgG antibodies to components of Ipa were removed in sera absorbed by S. flexneri, but IgG antibodies to Ipas--especially to Ipa D--were only slightly reduced in sera absorbed by S. sonnei, suggesting that Ipa D in S. sonnei may not be exposed on the S. sonnei cell surface.
Antibodies, Bacterial↗
Specificity of monoclonal antibodies binding to the polysaccharide antigens (Vi, O9) of Salmonella typhi.
A panel of monoclonal antibodies were generated against the surface polysaccharide antigens of the cell envelope of Salmonella typhi. Four clones (IgM) were specific for the capsular Vi polysaccharide, and one clone (IgG3) reacted selectively with the S. typhi lipopolysaccharide in enzyme immunoassay. On the basis of their reactivity pattern and binding affinity, MATy-V7 (IgM) and MATy-O9 (IgG3) antibodies were selected for further characterization of their antigenic specificity. In an inhibition enzyme immunoassay with rabbit factor-specific anti-Salmonella antibodies as the competing agents, the reactivity of MATy-V7 and MATy-O9 were significantly inhibited by the anti-Vi and anti-O9 antisera, respectively. Moreover, both the Vi- and O9-specific monoclonal antibodies were shown to be useful serotyping agents by correct identification in slide agglutination tests of 32 clinical isolates of all the S. typhi and other serogroup D salmonellae among a total of 140 bacterial isolates representing eight different Enterobacteriaceae genera tested.
Antibodies, Monoclonal↗