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M M McConnell

Publications and source records attributed to M M McConnell.

At least 37 records · Page 2Linked to original sources
PubMed1989

Properties of adherence factor plasmids of enteropathogenic Escherichia coli and the effect of host strain on expression of adherence to HEp-2 cells.

EPEC adherence factor (EAF) plasmids from three strains of enteropathogenic Escherichia coli (EPEC) - E2347/69 (O127:H6), E20517 (O111:H2) and E24582 (O142:H6) - were examined. The EAF plasmids were all marked with ampicillin resistance by transposition of Tn801 to give pDEP1, pDEP2 and pDEP11, respectively. All three plasmids showed incompatibility with an FIme and an FIV plasmid and had some similarity in restriction enzyme digest patterns. Plasmid pDEP1 differed from pDEP2 and pDEP11 in being autotransferring and fertility-inhibition positive. An EAF probe consisting of a 1 kb BamHI-SalI restriction endonuclease fragment of the prototype EAF-associated plasmid pMAR2 hybridized to similar-sized SalI-BamHI fragments of pDEP1 and pDEP11 but to a different-sized fragment of plasmid pDEP2. Loss of the EAF plasmids from EPEC strains resulted in a marked reduction in the ability of these strains to adhere to HEp-2 cells. The EAF-plasmid-negative variants did not express a 94 kDa outer-membrane protein (OMP). When these EAF plasmids were reintroduced into EAF-plasmid-negative EPEC strains a high level of adherence equivalent to that of the parent EPEC strains was restored and a 94 kDa OMP was usually expressed. However, when EAF plasmids were transferred into E. coli K12 or non-EPEC E. coli the host strains either did not adhere or adhered poorly to the HEp-2 cells. These transconjugants did not express a 94 kDa OMP.

Adhesins, Escherichia coli↗
PubMed1989

Characterization of a putative colonization factor (PCFO166) of enterotoxigenic Escherichia coli of serogroup O166.

Enterotoxigenic Escherichia coli (ETEC) of serogroup O166 gave mannose-resistant haemagglutination (MRHA) with bovine and human erythrocytes. The strains did not react with antisera prepared against the known colonization factors CFA/I, CFA/II, CFA/III, CFA/IV and PCFO159:H4. Strain E7476 of serotype O166:H27, which produced heat-stable enterotoxin (ST), was examined initially. It produced fimbriae about 7 nm in diameter. On SDS-PAGE two possible fimbrial polypeptides of molecular mass 15.5 and 17.0 kDa were seen. When variants of strain E7476 were isolated, loss of ST and MRHA together was associated with loss of a 98 MDa plasmid, while loss of ST alone correlated with plasmid deletion. An absorbed anti-strain E7476 antiserum reacted specifically with the 15.5 and 17.0 kDa polypeptides in Western immunoblotting and bound to the intact fimbriae by immuno-electron microscopy. When this antiserum was used in an ELISA to examine other strains of serogroup O166, a positive reaction was obtained with all the ST- and MRHA-positive strains. One strain of serotype O71:H27 and two strains of serotype O98:H- also reacted with the absorbed anti-strain E7476 antiserum. The antiserum did not react with ETEC carrying known colonization factors. E. coli K12 and a number of E. coli of different serotypes carrying a plasmid coding for ST transferred from strain E7476, all gave MRHA and reacted with the absorbed anti-strain E7476 antiserum. The term putative colonization factor O166 (PCFO166) is proposed to describe the adhesive factor(s) on ETEC of serogroup O166 because of the similarity of properties with those of known colonization factors.

Antibodies, Bacterial↗
PubMed1989

Characterization of CS4 and CS6 antigenic components of PCF8775, a putative colonization factor complex from enterotoxigenic Escherichia coli E8775.

PCF8775 is a putative colonization factor complex present on the surface of 10 to 20% of enterotoxigenic Escherichia coli strains and has been reported to be composed of antigen CS6 (morphology undefined) expressed alone or together with either of the rigid fimbrial antigens CS4 and CS5. To better define the individual components of this complex and the determinants of their expression, we prepared antiserum to the PCF8775 complex as it was expressed on prototype strain E8775 and then used the antiserum to identify the subunit structure of the antigens, to study their morphology, and to detect expression of individual components of the complex after transfer of plasmids into laboratory strain HB101. CS4 was purified from strain E8775, confirmed to be fimbrial by electron microscopy, and found to be composed of a 22-kilodalton protein subunit whose N-terminal amino acid sequence (1 to 20) was similar to that of colonization factor antigen I. Transconjugants that express CS6 but not CS4 were obtained by mating prototype strain E8775 with HB101. CS6 expression was mediated by a 61-megadalton plasmid. Expression of CS6 in the transconjugants correlates with expression of a 16-kilodalton cell surface protein. The CS6 antigen was confirmed to be present on the cell surface by immunogold labeling, but its morphology was beyond the limits of resolution by electron microscopy.

Animals↗
PubMed1989

Adhesion and ultrastructural properties of human enterotoxigenic Escherichia coli producing colonization factor antigens III and IV.

Human enterotoxigenic Escherichia coli (ETEC) producing colonization factor antigen III (CFA/III) and coli surface antigens 4, 5, and 6 (CS4, CS5, and CS6) of CFA/IV were examined ultrastructurally and for ability to adhere to human small intestinal enterocytes and to cultured human intestinal mucosa. Strains of serotypes O25:H-, O25:H42, and O167:H5 producing CFA/III plus CS6, CS4 plus CS6, and CS5 plus CS6, respectively, showed good adhesion to human enterocytes (1.8 to 4.2 bacteria per brush border) and cultured human intestinal mucosa, whereas variants lacking these antigens or producing only CS6 were nonadherent (0 to 0.03 bacterium per brush border). By electron microscopy, CFA/III, CS4, and CS5 appeared as morphologically distinct rodlike fimbriae: CFA/III was 7 to 8 nm in diameter, CS4 was 6 to 7 nm in diameter, and CS5 was 5 to 6 nm in diameter. CS5 was unusual in that it appeared to be composed of two fine fibrils arranged in a double-helical structure. CS6 was difficult to characterize morphologically but possibly has a very fine fibrillar structure. By specific fimbrial staining and immunoelectron microscopy. CS4 and CS5 were shown to promote mucosal adhesion of ETEC; a similar adhesion role for the CS6 antigen could not be confirmed. ETEC strains of serotypes O27:H7, O27:H20, O148:H28, and O159:H20 which produced CS6 showed good adhesion to human enterocytes (1.6 to 3.0 bacteria per brush border), whereas variants which lacked CS6 were nonadherent (0 to 0.01 bacterium per brush border). These strains, however, also produced fimbrial or fibrillar surface antigens, in addition to CS6, which probably represent additional coli surface antigens responsible for the observed adhesive properties of these ETEC serotypes.

Antigens, Bacterial↗
PubMed1988

Role of PCF8775 antigen and its coli surface subcomponents for colonization, disease, and protective immunogenicity of enterotoxigenic Escherichia coli in rabbits.

The role of the PCF8775 antigen and its antigenic subcomponents, in particular, the coli surface (CS) antigen CS6, as colonization factors and protective antigens was studied in the reversible intestinal tie adult rabbit diarrhea model. This was done by testing the abilities of different mutants which carried one or two of the CS components to colonize the intestine and to induce protective immunity against reinfection with PCF8775-positive enterotoxin-producing Escherichia coli. Infection with enterotoxigenic E. coli carrying CS4-CS6, CS5-CS6, or CS6 alone induced diarrhea in 75% or more of the rabbits, whereas the corresponding nonenterotoxigenic mutants, as well as enterotoxigenic but CS-negative strains, induced diarrhea in only a few cases. Mutants carrying CS6 alone colonized the intestine equally as well as strains carrying CS4-CS6 or CS5-CS6 did, whereas CS-negative mutants were excreted in the stool for a significantly shorter period. Rabbits previously infected with mutants carrying CS6 alone or CS6 in combination with CS4 or CS5 developed diarrhea with a significantly lower frequency after reinfection with a normally highly diarrheagenic dose of enterotoxigenic CS4-CS6-positive E. coli bacteria than did animals immunized with corresponding CS-negative mutants. Fecal excretion of the rechallenge strain was also of considerably shorter duration than that observed after initial infection with corresponding strains in 27 of the 30 animals (90%) immunized with strains carrying CS6 alone or in combination with CS4 or CS5. Such reduced shedding of the challenge strain was only seen in a few rabbits (3 of 12) initially infected with CS-negative bacteria. These results suggest that the CS6 component of PCF8775 is a colonization factor in rabbits and that it is also capable of inducing protective immunity.

Animals↗
PubMed1988

Genetic control and properties of coli surface antigens of colonization factor antigen IV (PCF8775) of enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli producing coli surface antigen 4 (CS4), CS5, and CS6 of colonization factor antigen IV were examined. This factor was originally called putative colonization factor 8775 (PCF8775). All of the coli surface antigens were plasmid coded and were usually carried on the same plasmid as the genes coding for heat-stable toxin (ST) or heat-labile toxin (LT); thus, CS5-CS6-ST, CS6-ST, and CS6-LT plasmids were found. In strains of serotype O25:H42, the genes coding for CS4 and CS6 were on a plasmid separate from that containing the genes coding for ST and LT. CS4 and CS5 were fimbrial antigens with a subunit molecular mass of about 17.0 and 21.0 kilodaltons (kDa), respectively. CS6 was found as a single polypeptide with a molecular mass of about 14.5 kDa in strains of serotypes O25:H42, O27:H7, and O27:H20 when heated extracts were run on sodium dodecyl sulfate-polyacrylamide gels. CS6-positive extracts of strains of serogroups O148, O159, and O167 showed two bands with molecular masses between 14.5 and 16.0 kDa.

Antigens, Bacterial↗
PubMed1987

In strains of Escherichia coli O167 a single plasmid encodes for the coli surface antigens CS5 and CS6 of putative colonization factor PCF8775, heat-stable enterotoxin, and colicin Ia.

Twenty Escherichia coli strains of serogroup O167 were examined. They all produced the two surface antigens CS5 and CS6 of the putative colonization factor PCF8775, together with heat-stable enterotoxin and colicin Ia. A plasmid coding for CS5, CS6, heat-stable enterotoxin, and colicin Ia was demonstrated in each strain.

Antigens, Bacterial↗
PubMed1986

Bacteriophages F0lac h, SR, SF: phages which adsorb to pili encoded by plasmids of the S-complex.

Phage F0lac is an RNA-containing phage which plates only on strains carrying the plasmid EDP208, a pilus derepressed derivative of the unique incompatibility plasmid F0lac. A host range mutant, phage F0lac h, was selected which plated on strains carrying the ungrouped plasmid pPLS::Tn5 and lysed strains carrying another ungrouped plasmid TP224::Tn10 or the Com9 plasmid R71. An RNA-containing phage, SR, was isolated from sewage on bacteria harbouring plasmid pPLS::Tn5. It was antigenically distinct from the above two phages but had the same host range as phage F0lac h. Phages F0lac h and SR adsorbed unevenly to the shafts of the conjugative pili. Another phage, SF, was filamentous and plated or propagated on strains carrying any of the above plasmids as well as on strains harbouring IncD or F-complex plasmids. Plasmids TP224::Tn10 and pPLS::Tn5 were compatible with representative plasmids of all Inc groups also encoding thick flexible pili. The four plasmids EDP208, R71, TP224::Tn10 and pPLS::Tn5 were compatible with one another except for the reaction of TP224::Tn10 in the presence of pPLS::Tn5 which was slightly ambiguous. The host ranges of the bacteriophages, together with the serological relatedness of the thick flexible pili determined by these four compatible plasmids, suggested that they constitute a new complex, here designated S.

Adsorption↗
PubMed1985

Expression of cloned plasmid regions encoding colonization factor antigen I (CFA/I) in Escherichia coli.

Molecular cloning from a plasmid encoding colonization factor antigen I (CFA/I) and heat-stable enterotoxin isolated two regions, 1 and 2, that are required for the production of CFA/I fimbriae. The level of CFA/I synthesis measured by ELISA was similar in an Escherichia coli K12 strain carrying regions 1 and 2 cloned separately on compatible plasmid vectors to that in the same strain containing the parental plasmid. The structural gene for the CFA/I fimbrial subunit was within region 1. This region directed production in E. coli minicells of at least six independent polypeptides, of which the fimbrial subunit and at least three others appeared to be synthesized as precursor molecules that underwent processing. Cloned DNA containing CFA/I region 2 specified three polypeptides in minicells. Attempts to reduce the size of the cloned region 1 resulted in a derivative plasmid that carried the CFA/I structural gene but did not complement a region-2 recombinant plasmid to restore production of CFA/I fimbriae.

Antigens, Bacterial↗
PubMed1985

Enzyme-linked immunosorbent assays for the detection of adhesion factor antigens of enterotoxigenic Escherichia coli.

Two hundred forty-four specimens of Escherichia coli isolated in Bangladesh and Thailand and identified as enterotoxin producers were tested for the presence of adhesion antigens by mannose-resistant hemagglutination, immunodiffusion, and enzyme-linked immunosorbent assays (ELISAs). Specific antisera to the antigens colonization factor antigen (CFA)/I, CFA/II (consisting of coli surface antigens [CS] 1, 2, and 3), and putative colonization factor antigen (PCF) 8775 (consisting of CS4, 5, and 6) were used in immunodiffusion tests and ELISAs. The results showed that the antigens could be detected in more strains by ELISA than by immunodiffusion. Twenty-nine percent of specimens of E. coli from Thailand and 47% from Bangladesh carried an adhesion antigen. Many of the strains had lost the ability to produce enterotoxins. Forty percent of strains from Thailand and 64% from Bangladesh that were still enterotoxigenic carried adhesion factors. These antigens were found on strains with heat-stable or heat-stable and heat-labile enterotoxin but not on strains producing only heat-labile enterotoxin. PCF8775 antigens were associated mainly with strains from Bangladesh, where 10 strains that produced only CS6 were detected.

Adolescent↗
PubMed1985

The possession of three novel coli surface antigens by enterotoxigenic Escherichia coli strains positive for the putative colonization factor PCF8775.

A possible colonization factor, E8775, has previously been described for enterotoxigenic Escherichia coli strains of serogroups O25, O115 and O167. Re-examination of these strains by immunodiffusion has revealed that the antigenic nature of this factor, renamed putative colonization factor (PCF) 8775, is more complex than was first thought. All the strains of serogroup O25 tested possessed two antigenic components, termed CS4 and CS6, and gave mannose-resistant haemagglutination (MRHA) of human and bovine erythrocytes. Spontaneous variants possessing CS6 only did not give MRHA. Strains of serogroups O115 and O167 had the antigenic components CS5 and CS6, and gave MRHA of human, bovine and guinea-pig erythrocytes. Using immune electron microscopy, the components CS4 and CS5 were identified as fimbriae. No fimbriae were associated with CS6.

Antigens, Bacterial↗
PubMed1985

Properties of wild-type strains of enterotoxigenic Escherichia coli which produce colonization factor antigen II, and belong to serogroups other than O6.

Enterotoxigenic strains of Escherichia coli, which belonged to serogroups other than O6 and produced colonization factor antigen II, usually produced only coli surface antigen 3 (CS3) and gave weak mannose-resistant haemagglutination of bovine erythrocytes. A non-autotransferring plasmid, NTP165, from a strain of E. coli O168. H16 coded for heat-stable enterotoxin, heat-labile enterotoxin and CS antigens. The CS antigens expressed after acquisition of plasmid NTP165 depended on the recipient strain: a biotype A strain of serotype O6. H16 expressed CS1 and CS3; a biotype C strain of serotype O6. H16 expressed CS2 and CS3; strain K12 and strain E19446 of serotype O139. H28 expressed only CS3. An exceptional wild-type strain, E24377, of serotype O139. H28 produced CS1 and CS3 when isolated; a variant of E24377 which had lost the plasmid coding for CS antigens produced both CS1 and CS3 after the introduction of NTP165.

Antigens, Bacterial↗
PubMed1983

Expression of plasmids coding for colonization factor antigen II (CFA/II) and enterotoxin production in Escherichia coli.

Two plasmids transferred from enterotoxigenic Escherichia coli (ETEC) of serotype O6. H16 and biotypes A and C coded for mannose-resistant haemagglutination (MRHA) and production of heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT). Both plasmids were nonautotransferring being mobilized most efficiently by the R plasmid R100-1. They were similar in their genetic properties being incompatible with each other and plasmids of the Inc group FI. The wild-type strains produced the colonization factor antigen II (CFA/II) which was made up of different coli surface antigens (CS). The biotype A strains produced CS1 and CS3 while the biotype C strains produced CS2 and CS3. These three antigens have the ability to cause MRHA. When plasmids coding for MRHA were transferred to K12 strains, the degree of haemagglutination was markedly reduced and only CS3 was produced. When both plasmids were transferred back into biotype A strains, good MRHA was restored and the strains produced CS1 and CS3. In a biotype C strain CS2 and CS3 were formed. The production of the antigens was compared by enzyme-linked immunosorbent assay (ELISA). The strains were also examined by electron microscopy where it was found that CS1 and CS2 were fimbrial antigens while CS3 was not.

Antigens, Bacterial↗
PubMed1982

Genetic and molecular studies of plasmids coding for colonization factor antigen I and heat-stable enterotoxin in several escherichia coli serotypes.

Plasmids coding for colonization factor antigen I (CFA/I) and heat-stable enterotoxin (ST) were identified in 10 strains of human enterotoxigenic Escherichia coli. The strains, which belonged to serogroups O63, O114, O128, and O153, were isolated in Bangladesh, Latin America, Spain, and South Africa. Two strains produced heat-labile enterotoxin in addition to ST. CFA/I-ST plasmids were mobilized from two O128 strains into E. coli K-12 with the R factor R1-19K-. Like the prototype CFA/I-ST plasmid NTP113, mobilized previously from an E. coli O78 strain into K-12, these two plasmids were non-autotransferring. All 10 CFA/I-ST plasmids were incompatible with NTP113 and had molecular weights ranging from 59 X 10(6) to 72 X 10(6). The molecular properties of seven of these plasmids were compared with those of six CFA/I-ST plasmids previously mobilized from O78 strains from Ethiopia, South Africa, and Bangladesh and with those of one plasmid coding for CFA/I, ST and heat-labile enterotoxin from a South African strain of serogroup O63. Digestion with the restriction endonuclease HindIII showed that several plasmids had very similar fragment patterns and two were identical. Generally, a larger proportion of HindIII fragments were of common size in digests of plasmids identified in strains from related geographical areas, regardless of serogroup. However, all except one plasmid shared five or six HindIII fragments of the same size, one of which had been shown previously to be involved in CFA/I production. There was at least 90% DNA homology between CFA/I-ST plasmids with a molecular weight of about 58 X 10(6) from O78 strains from different sources. Most of the DNA sequences of these plasmids were present in a larger CFA/I-ST plasmid (72 X 10(6) from an O128 strain. The results of genetic and molecular studies suggest that CFA/I and ST production is determined by very similar plasmids in different serogroups of human enterotoxigenic E. coli from several sources.

Antigens, Bacterial↗
PubMed1981

Plasmids coding for colonization factor antigen I and heat-stable enterotoxin production isolated from enterotoxigenic Escherichia coli: comparison of their properties.

We examined seven enterotoxigenic Escherichia coli strains which produced colonization factor antigen I (CFA/I). Four of these strains were from South Africa (three serotype O78:H12 and one serotype O63:H-), one was from Ethiopia (O78:H12), and two were from Bangladesh (O78:H11 and O78:H12). Plasmids coding for CFA/I were mobilized from six of these strains by using resistance or enterotoxin factors. No plasmid was mobilized from the serotype O78:H12 Bangladesh strain. The transconjugants obtained from crosses with the O78 strains also produced heat-stable enterotoxin (ST), and additional investigations showed that CFA/I and ST were coded for by a single non-autotransferring plasmid. These plasmids were fertility inhibition negative, did not restrict any of the coliphages with which they were tested, and were incompatible with each other. Four had molecular weights of approximately 60 X 10(6), and one had a molecular weight of 52 X 10(6). Like the other CFA/I plasmids, the CFA/I plasmid transferred from the O63:H- strain coded for ST, but this plasmid also coded for heat-labile enterotoxin. In most other respects the properties of this plasmid were similar to those of the CFA/I-ST plasmids previously described. The molecular weight of this plasmid was 65 X 10(6). The IncT R-factor Rtsl was marked with a transposon for tetracycline resistance and then transferred into the two Bangladesh wild-type strains. Plasmids which coded for tetracycline resistance, CFA/I, and ST were transferred from these strains. These plasmids were incompatible with Rtsl and with the CFA/I-ST plasmids described above and were recombinants between Rtsl and a CFA/I-ST plasmid. Their properties are also described.

Antigens, Bacterial↗
PubMed1980

Evaluation of an assessment and training unit for developmentally delayed children.

The Rata villa assessment and training unit is intended to provide a short term community service for the evaluation and treatment of developmentally delayed children who are becoming difficult to manage at home or in community educational or training facilities. Since it opened the unit has dealt with 102 first admissions with a wide variety of problems, ranging in age from two to 15 years and varying in intellectual level from normal intelligence to profoundly retarded. In 71 percent of these cases permanent improvements have been made in at least one of the problem areas identified by the child's parents on admission. The treatment programmes are considered to have contributed to maintaining the child in the community as only 28 percent of those treated are currently long term residents in psychopaedic hospitals.

Adolescent↗
PubMed1980

Plasmids coding for heat-labile enterotoxin production isolated from Escherichia coli O78: comparison of properties.

Nineteen enterotoxigenic Escherichia coli strains of serogroup O78, isolated in different geographical areas from humans with diarrheal diseases, were tested for their ability to transfer enterotoxin production. All of the strains originally produced heat-labile enterotoxin, and 16 also produced heat-stable enterotoxin and colonization factor antigen I. Plasmids coding for the production of heat-labile enterotoxin only were transferred from 13 strains. Some properties of these plasmids were compared. All were fi+, but they could be divided into three groups on the basis of their incompatibility reactions, ability to restrict E. coli K-12 phages, and size. The three heat-labile enterotoxin plasmids isolated from African strains all belonged to one enterotoxin plasmid group. The heat-labile enterotoxin plasmids from the Asian strains were divided into two groups, those from serotype O78.H11 differing from those from serotype O78.H12.

Bacterial Toxins↗