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P Gemski

Publications and source records attributed to P Gemski.

At least 37 records · Page 2Linked to original sources
PubMed1985

High frequency transduction by phage hybrids between coliphage phi 80 and Salmonella phage P22.

phi 80immP22dis, a hybrid between phi 80 and P22, carries all the late genes of phi 80 and most of the P22 early region including the immC and immI bipartite immunity loci. The presence of the immI region allows this hybrid to grow on lysogens of phi 80immP22 hybrids which have the immC locus, but not the immI locus. In addition to these P22 immunity regions, phi 80immP22dis contains the P22 att marker so that the prophage can be inserted into the chromosomal P22 attachment site adjacent to the proA-proB region of the host. Unlike its phi 80 parent which performs specialized transduction of the trp region, phi 80immP22dis transduces markers located adjacent to its attachment site to Escherichia coli K12 recipients at high frequencies (0.3% for argF and 0.18% for proA). Induction of phi 80immP22dis lysogens yields new hybrid phage clones which have incorporated E. coli K12 chromosomal segments in place of the P22 immI to att segment. Having lost the immI region, the new hybrids no longer grow in phi 80immP22 lysogens. These new hybrids, termed phi 80immP22dis-, possess specialized transducing properties, transferring the argF and proA markers at higher frequencies (21% for argF and 12% for proA) than previously obtained with the phi 80immP22dis phage.

Coliphages↗
PubMed1984

The importance of the K1 capsule in invasive infections caused by Escherichia coli.

We examined 534 clinical isolates of Escherichia coli for sensitivity to rough lipopolysaccharide-specific and K1-specific phages. Twenty-eight percent of bacteremic isolates were sensitive to rough-specific phages. Forty-two percent of these strains, against only 20% of bacteremic isolates insensitive to rough-specific phages, had K1 capsule (P less than 0.001). K1-positive strains were usually resistant to phagocytic killing, whereas strains lacking the K1 capsule were more likely to be killed regardless of capsular type. Eighty-two percent of strains were typable with O-specific, 57% with K-specific, and 74% with H-specific antisera. Sixty percent of E coli were agglutinated by only 10 O-specific antisera. K1 was the most common capsular type, followed by K5, K2, and K12, whereas four H antigens accounted for nearly half of the H-typable strains. We conclude that (1) the combination of rough-specific and K1-specific phage sensitivity defines functionally similar groups of bacteria and (2) a polyvalent vaccine against invasive E coli is possible given the relatively limited number of invasive O:K:H serotypes.

Adolescent↗
PubMed1984

Heterogeneity of lipid A: comparison of lipid A types from different gram-negative bacteria.

Chloroform-soluble purified lipid A preparations from 10 sources, including five Escherichia coli strains (EH100, K-12, O127, O111, RCDC), two Salmonella strains (Salmonella typhimurium, Salmonella minnesota R595), Shigella sonnei II, and a hybrid of Shigella flexneri and E. coli K-12, were compared with lipid A from S. flexneri. Purified lipid A from S. flexneri was earlier found to be composed of eight fractions. The various lipid A preparations were assayed by thin-layer chromatography. Chromatograms were stained for phosphate or carbohydrate by molybdenum blue or orcinol, respectively. The number of major bands found for each lipid A preparation varied between 7 and 10, depending on the source. Comparable bands, based on Rf, were found among all of the different lipid A preparations, but the quantity of each band varied between the sources of lipid A. Four bands (designated 2, 3, 7, and 8) were abundant in every preparation. Variations of conditions used for preparing lipid A, such as changing of hydrolysis time, did not affect the appearance of lipid A on thin-layer chromatography. Change in the type of acid used for hydrolysis also did not affect the band pattern, but it did change the quantitative amounts of the various bands to some degree.

Chromatography, Thin Layer↗
PubMed1984

Identification of Escherichia coli K1 antigen.

We compared the use of bacteriophage sensitivity, seroagglutination with polyclonal antisera raised in rabbits or horses, seroagglutination with murine monoclonal antibody, and the serum agar precipitin technique for the detection of K1 capsular polysaccharide among clinical isolates of Escherichia coli obtained from blood stream infections. Some E. coli isolates failed to yield agreement among these tests, indicating that reliable detection of K1 antigen may require the use of multiple tests.

Agglutination Tests↗
PubMed1983

Structural studies of the Escherichia coli O-antigen 25.

The structure of the Escherichia coli O-antigen 25 has been investigated using n.m.r. spectroscopy, methylation analysis, and various specific degradations. It is concluded that the O-antigen is composed of pentasaccharide repeating-units having the following structure.

Antigens, Bacterial↗
PubMed1983

Evaluation of immunotherapeutic approaches for the potential treatment of infections caused by K1-positive Escherichia coli.

Levels of antibody to the K1 polysaccharide capsule were examined in sera from patients naturally infected with K1-positive Escherichia coli, in sera from volunteers vaccinated with a group B meningococcal vaccine, in immune globulin prepared for intravenous use, and in a preparation of murine IgM monoclonal antibody to group B meningococci. In a phagocytic assay, the monoclonal antibody in mouse ascites fluid killed K1-positive E. coli to a final dilution of 1:250,000 (48 ng of antibody protein/ml); no killing was observed with any of the other antibody sources. This monoclonal antibody, which required human complement and exhibited a prozone when high concentrations of antibody (greater than 6 micrograms/ml) were used, killed all K1-positive strains but none of the K1-negative strains of E. coli tested. Levels of K1-binding antibody in the sera of vaccinated volunteers exceeded antibody levels resulting from natural infection or present in commercially prepared immunoglobulin and were less than those obtained in mouse ascites fluid containing the monoclonal antibody.

Antibodies, Bacterial↗
PubMed1983

Genetic studies of hybrids between coliphage phi 80 and Salmonella phage P22.

Hybrids between Escherichia coli phage phi 80 and Salmonella typhimurium phage P22 were isolated after superinfection by P22 of a smooth E. coli-S. typhimurium hybrid lysogenic for phi 80. These hybrid phages, designated phi 80immP22 and phi 80immP22dis, possessed the phi 80 protein coat and tail genes. The phi 80immP22 hybrids acquired the immunity (immC) region of P22 and some adjacent P22 genes, but E. coli-S. typhimurium strains lysogenic for phi 80immP22 hybrids remained sensitive to P22. The phi 80immP22dis hybrids, found ten times more frequently than the phi 80immP22 hybrids, contained a more extensive portion of the P22 genome which encompassed the immI as well as the immC region of P22. Therefore, the phi 80immP22dis hybrids conferred on their hosts immunity to P22 infection. Further analyses have revealed that the phi 80immP22dis hybrids carry the P22 attachment region and either P22 tail gene 9 or antigen conversion gene a1, but not both of these genes.

Coliphages↗
PubMed1983

Release of Shiga toxin from Shigella dysenteriae 1 by polymyxin B.

Release of Shiga toxin from Shigella dysenteriae 1 was found to occur after exposure to polymyxin B. The amount of toxin released was dependent on both the polymyxin concentration and time of incubation. An immunoblot characterization of the Shiga toxin released by polymyxin treatment demonstrated that it is electrophoretically similar to purified Shiga toxin and to Shiga toxin present in crude bacterial sonicates of S. dysenteriae 1 cells.

Animals↗
PubMed1983

Virulence and phenotypic characterization of Yersinia enterocolitica isolated from humans in the United States.

Yersinia enterocolitica was recently reclassified into Yersinia enterocolitica sensu stricto and three additional species. With this new classification, it was of interest to reexamine pathogenicity previously ascribed to Y. enterocolitica. All available clinical isolates of Y. enterocolitica sent to the Centers for Disease Control from 1970 through 1980 were selected for characterization and comparison. One-hundred such strains had been submitted, from 21 states. Most (85%) were biotype 1, and O:8 was the most common of the 24 serotypes encountered. All strains were examined by several virulence assays. Two strains caused conjunctivitis in guinea pigs, 7 were lethal for mice, 54 invaded HEp2 cells, 18 produced a heat-stable enterotoxin, 9 were calcium dependent, 20 autoagglutinated, and 34 had a distinctive colonial morphology at 37 degrees C. Ten isolates of each of the new species that had previously been grouped with Y. enterocolitica (Y. kristensenii, Y. intermedia, and Y. frederiksenii) were characterized and were generally negative in all assays. This study points out pathogenicity differences among Yersinia species, confirms the complex nature of virulence in Y. enterocolitica, and confirms that no single current assay correlates with virulence in Y. enterocolitica.

Agglutination↗
PubMed1982

K antigen and serum sensitivity of rough Escherichia coli.

We prepared bacterial hybrids which express both K1 and K27 antigens and examined the relative contributions of these capsules to serum resistance. Escherichia coli Hfr strain F639 (rough, K27+, serum sensitive) was conjugated with E. coli recipient strain E412 (rough, K1+, His- Trp- Strr, serum resistant). Transconjugants which inherited both the his and trp linked genes for K27 antigen synthesis were analyzed. These hybrids retained and expressed the K1 antigen since the K1 locus is nonallelic with K27 gene loci. Hybrid strains which express both K1 and K27 antigens exhibit serum resistance, but not at the level of the K1+ parental strain. An isogenic K1 derivative of a hybrid which expressed only K27 antigen was serum sensitive (greater than 99% kill, 60 min). These findings indicate that the presence of the K1 capsular antigen can protect some rough strains of E. coli from serum bactericidal activity, whereas K27 and perhaps other K antigens fail to provide such a protective effect.

Antigens↗
PubMed1982

New virulence-associated plasmid in Yersinia enterocolitica.

In a study of 103 strains of Yersinia enterocolitica, 10 strains were found to be lethal for mice and to possess 42- and 82-megadalton plasmids. This association was statistically significant (P much less than 0.001). Serotypes of Y. enterocolitica previously considered avirulent were found to possess these plasmids and to be lethal for mice. A spontaneous derivative of one strain contained only the 82-megadalton plasmid and was lethal for mice anyway. This virulence-associated plasmid is a potential diagnostic tool for the clinical or public health laboratory which must delineate pathogenic strains of Y. enterocolitica.

Animals↗
PubMed1981

Role of antigen form in development of mucosal immunoglobin A response to Shigella flexneri Antigens.

One major stumbling block in the development of an effective means to immunize against shigellosis and other enteric diseases has been the lack of a means to assess sequential mucosal immune responses to different potential immunogens. In the present study, we compared the abilities of live invasive organisms, noninvasive organisms, and nonviable antigen preparations of shigella to elicit mucosal immune responses. Whereas previous studies have found that effective immunity was produced best by vaccination with live invasive strains of shigella, in the present study, live noninvasive strains that did not produce any histopathological damage were consistently able to produce local (immunoglobulin A) immune responses as vigorous as those of the invasive strains. Further, acetone-killed shigella antigen was also an effective mucosal immunogen, whereas hot phenol-water-extracted shigella lipopolysaccharide was ineffective, possibly due to the method of preparation. A single oral or parenteral priming was ineffective in enhancing the mucosal immune response when restimulated 1 month later with the same antigen. However, a mucosal memory response was found to be present several months after a triple mucosal stimulation with a locally invasive vaccine strain.

Administration, Oral↗
PubMed1980

Presence of a virulence-associated plasmid in Yersinia pseudotuberculosis.

We have shown that Yersinia pseudotuberculosis can possess plasmids which are similar in size and function to the previously described Vwa plasmids of Y. enterocolitica. These plasmids are associated with the production of V and W antigens (calcium dependency) and pathogenicity of the organism. Further investigation of these plasmids from Y. pseudotuberculosis and Y. enterocolitica with restriction endonucleases revealed significant differences in their fragmentation pattern.

DNA Restriction Enzymes↗
PubMed1980

Variables affecting local immune response in ileal loops: role of immunization schedule, bacterial flora, and postsurgical inflammation.

Several variables inherent in chronically isolated ileal (Thiry-Vella) loops in rabbits were studied for their effect on the local immune response of the intestine to live, locally invasive bacteria (Shigella X16). A much more vigorous local immunoglobulin A response to Shigella X16 was elicited when rabbits were immunized in their Thiry-Vella loops shortly after surgical creation of the loop than if a week were allowed to pass before they were immunized. Three major differences existed in Thiry-Vella loops on the day after surgery and a week later: (i) their microbial flora, (ii) nonspecific acute inflammation due to the surgery itself, and (iii) the histological appearance of the intestine. On day 1 after surgical creation of the Thiry-Vella loop, there were few bacteria in the loop, and the histology was that of normal small bowel except for mild acute inflammation due to the surgery. By day 6 after surgery, all loops contained large numbers of Pseudomonas aeruginosa and other aerobes, an atrophy of intestinal epithelium occurred, and the acute inflammation due to surgical trauma had subsided. By artificially colonizing Thiry-Vella loops with 10(8) or 10(10) live P. aeruginosa on the day of surgery, we found that the presence of these bacteria alone did not greatly diminish local immune responses to live Shigella. Furthermore, when the acute inflammation due to surgical trauma was recreated in loops 6 days old, no enhancement of the immune response was seen as compared to nontraumatized 6-day-old Thiry-Vella loops. The difference between immunization soon after surgery and a week later related to changes that occur in the loop itself with increased isolation. Finally, multiple immunizations of Thiry-Vella loops resulted in a more vigorous local immunoglobulin A response than a single immunization. These studies demonstrated that Thiry-Vella loop models can be useful in studying the kinetics of local immune responses by the intestine only if careful attention is paid to key variables inherent in the Thiry-Vella loop models themselves.

Animals↗
PubMed1980

Isolation and characterization of minicell-producing mutants of Shigella spp.

Minicells are small, anucleate cells resulting from aberrant cell divisions at the polar ends of bacilli. We have isolated minicell-producing mutant strains of Shigella flexneri 2a (MC-I) and Shigella dysenteriae 1 (MC-V) after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Microscopically, broth cultures of MC-I and MC-V were found to contain free minicells, normal cells, and filamentous cells with polar, attached minicells. Both strains retained their ability to provoke keratoconjunctivitis in guinea pigs and to invade HeLa cells. Purified suspensions of minicells containing less than one whole cell per 10(6) minicells were obtained by a combination of differential sedimentation and density gradient centrifugation (5 to 30% [wt/vol] linear sucrose gradients). Each MC-I minicell contained about 0.005 times the amount of deoxyribonucleic acid of one normal S. flexneri. The MC-V minicell had about 0.003 times the amount of deoxyribonucleic acid of one whole S. dysenteriae cell. Purified MC-V minicells were treated with polymyxin B to release Shiga toxin. Shiga toxin was readily detected in MC-V minicells by means of a microtiter HeLa cell cytotoxicity assay. Our findings indicate that such a minicell-producing alteration in the cell division cycle of shigellae has not significantly affected their virulence.

Cell Division↗
PubMed1979

Shigellosis and Escherichia coli diarrhea: relative importance of invasive and toxigenic mechanisms.

Shigellae and dysentery-like Escherichia coli must invade the epithelium of the colon to cause disease which can present as dysentery, diarrhea, or both. This paper addresses the possible role of a Shigella dysenteriae-like (Shiga-like) toxin in the pathogenesis of shigellosis and E. coli diarrheal diseases. The possibility for such a role is suggested by the following observations: 1) diarrhea, considered to be a result of secretion of water by the small bowel, is frequently observed in shigellosis, a large bowel disease. 2) Even though shigellae do not invade the jejunum of monkeys fed Shigella flexneri, jejunal secretion is seen in animals with diarrhea. 3) The Shiga toxin of S. dysenteriae has enterotoxic activity and other serotypes of shigellae produce Shiga-like toxins. 4) E. coli 015 RDEC-1 causes a diarrheal disease and frequently death in young rabbits. This organism neither produces E. coli enterotoxins nor is it invasive, but it may produce low levels of a Shiga-like toxin.

Animals↗
PubMed1978

lambdaimm P22dis: a hybrid of coliphage lambda with both immunity regions of Salmonella phage P22.

Genetically marked lambda and P22 phages were recombined in Escherichia coli-Salmonella typhimurium hybrid WR4028, a host sensitive to infection by both of these phages. Hybrid phages that acquired the immC region of P22, but retained the genes for the lambda protein coat were selected on WR4027 (lambda), a lambda-immune, P22-resistant derivative of WR4028. In these lambdaimmP22 hybrids, at least the c through P genes of lambda were replaced with functionally related P22 genes. Phage recombinants with more extensive regions of the P22 genome were selected on the double lysogen WR4027 (lambda, lambdaimmP22). One such hybrid, lambdaimmP22dis, was determined by heteroduplex analysis to contain approximately 40% of the P22 genome. Genetic studies established that lambdaimmP22dis possesses the two widely separated immunity control regions of P22 (immC and immI) and that these loci are expressed in E. coli K-12 lysogenic for lambdaimmP22dis. In addition, lambdaimmP22dis contains the P22 a 1 locus responsible for somatic 0--1 antigen conversion in Salmonella. Although the lambdaimmP22dis phage particle has the lambda head and tail, the phage genome also carried P22 tail gene 9 as evidenced by the production of free P22 tails. It also has the P22 att site as indicated by the integration of the lambdaimmP22dis prophage near the proA locus on the bacterial chromosome.

Antigens, Bacterial↗