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G Jonson

Publications and source records attributed to G Jonson.

At least 19 recordsLinked to original sources
PubMed2002

The humoral response to live and inactivated influenza vaccines administered alone and in combination to young adults and elderly.

BACKGROUND: Vaccination is the most effective way for prevention of severe influenza infection, but the present vaccines are not very efficient in the elderly. OBJECTIVE: In this study, we investigated the Ig isotype response to a cold adapted, live, attenuated influenza vaccine (LIV) and a trivalent, subunit, inactivated influenza vaccine (IIV) and the combination of both (LIV/IIV) in young and elderly men, not previously vaccinated against influenza. STUDY DESIGN: LIV and IIV containing the strains for 1998-1999 were used. Forty-seven 19-35 years old and forty-three 58-91 years old were divided in four groups receiving either LIV, IIV, both or placebo. All were bled before and at 4 weeks after vaccination. The hemagglutination inhibition (HAI) antibody response to homologous strains and the enzyme-linked immunosorbent assays (ELISA) IgA, IgG and IgG-subclass responses to recombinant HA proteins representing influenza A and B strains from 90 to 91, and purified virus from an A/Sydney/05/97-like strain were measured. RESULTS: Protective HAI titers of >40 were more frequent (P<0.05) after IIV alone or LIV/IIV than after LIV alone; there was no difference between the young and elderly persons. The highest frequency of titer rises in ELISA was found against the H1N1 recombinant antigen. In young adults, IgG titer rises were more frequent than in elderly given LIV than IIV alone, but not when given the combination. The influenza-specific IgG subclass response after LIV consisted of IgG1 and IgG4 only in the young; after IIV it stimulated of IgG1 and IgG3 in the young and IgG1 alone in the elderly. After vaccination with the LIV/IIV combination IgG1, IgG3 and IgG4 were found in the young and IgG1, IgG3 in the elderly. Among the elderly, the IIV/LIV combination induced the same response rate of specific IgG and IgG1 as in young adults. CONCLUSION: The study illustrates the possibility to correct the age dependent weakening of the immune response to influenza vaccine with a combination of LIV and IIV.

Adult↗
PubMed1997

Serum amyloid P component binds to influenza A virus haemagglutinin and inhibits the virus infection in vitro.

Serum amyloid P component (SAP) is a member of the phylogenetically conserved and structurally related group of proteins called pentraxins. SAP exhibits multispecific calcium-dependent binding to oligosaccharides with terminal N-acetyl-galactosamine, mannose and glucuronic acid. The authors report that SAP can bind to influenza A virus and inhibit agglutination of erythrocytes mediated by the virus subtypes H1N1, H2N2 and H3N2. SAP also inhibits the production of haemagglutinin (HA) an the cytopathogenic effect of influenza A virus in MDCK cells. The binding of SAP to the virus requires physiological calcium concentrations and is blocked by specific SAP antibodies. Denaturated and renaturated SAP retained inhibition of HA. Electron microscopy shows Ca(2+)-dependent binding of SAP to spikes on the viral envelope and immunoblotting indicates that SAP binds to a 50-55 kDa peptide corresponding to the mass of the HA1 peptide. Of several monosaccharides tested only D-mannose interfered with SAP's inhibition of both HA and infectivity. The glycosaminoglycans heparan sulfate and heparin, which bind SAP, reduced SAPs binding to the virus. The results indicate that the inhibition by SAP is due to steric effects when SAP binds to terminal mannose on oligosaccharides localized close to the sialic acid-binding site of the HA trimer.

Acetylgalactosamine↗
PubMed1997

Immune response to the mannose-sensitive hemagglutinin in patients with cholera due to Vibrio cholerae O1 and O0139.

The mannose-sensitive hemagglutinin (MSHA) is a type 4 pilus present in Vibrio cholerae O1 strains of the El Tor biotype, as well as in strains of serogroup O139. It has been shown to be a colonization antigen in animal models. The aim of this study was to investigate systemic and local antibody responses to MSHA in adult patients with cholera due to V. cholerae O1 and O139. Twenty-four of 28 (86%) patients with O1 cholera and 11 of 17 (65%) patients with O139 cholera showed significant increases in MSHA-specific immunoglobulin A (IgA) and IgM antibody-secreting cells (ASCs) 7 days after the onset of disease. However, the magnitude of the ASC response in O1 cholera patients was significantly higher than that in the O139 cholera patients in both IgA-producing (P = 0.015) and IgM-producing (P = 0.029) cells. Both groups of patients responded with antibody responses to MSHA in plasma, seroconverting with both IgA (63 to 70% of patients) and IgG (43 to 59% of patients) antibodies. Compared to the MSHA-specific antibody levels determined in healthy controls (n = 10), more than 90% of O1 and O139 cholera patients showed responses to MSHA of both the IgA and the IgG isotypes. About 70% of the patients in both groups also had antibody responses to MSHA in their feces. In summary, we demonstrated that MSHA is immunogenic, giving rise to both systemic and local antibodies in patients with cholera due to both O1 and O139 serogroups.

Adolescent↗
PubMed1996

The structural gene encoding human enterotoxigenic Escherichia coli PCFO20 is homologous to that for porcine 987P.

Putative colonization factor PCFO20 was recently identified in an enterotoxigenic Escherichia coli (ETEC) strain of serogroup O20 isolated from a child with diarrhea in Argentina. The gene encoding the structural subunit of PCFO20 fimbriae, fotA, was cloned from strain ARG-2 in the expression phage vector lambda ZAP Express. One positive clone, pGV29, that carried a 3.3-kb fragment was identified on the basis of fimbrillin production by using a monospecific rabbit anti-PCFO20 serum. Nucleotide sequencing of a 1.3-kb Sau3A-ClaI fragment of the subclone pGV292 containing the region coding for PCFO20 fimbrillin revealed two open reading frames of which one was complete. A western blot (immunoblot) showed that the cloned protein, FotA, migrated like the PCFO20 fimbrial subunit protein did. Fimbriae were not detected on the surface of E. coli host bacteria containing pGV292 or pGV29, suggesting that the genes needed for assembly of PCFO20 fimbriae are lacking in both clones. The fotA gene encodes a 20,574-Da prefimbrillin protein which contains a 21-amino-acid signal sequence; the mature protein has a size of 18.1 kDa. The subunit protein FotA was found to be more homologous to the subunit of porcine 987P than to any fimbrial subunit produced by human ETEC. Alignments of the amino acid sequences of the two proteins indicate that they are partly identical, with an overall similarity of 82%. FotA fimbrillin was shown to be transported and assembled by the fimbria assembly machinery in porcine ETEC strain 987. PCFO20 and 987P may have evolved from a common ancestral gene. They are immunologically related but have affinity for different host cell receptors, since PCFO20-producing bacteria do not bind to neonatal piglet enterocytes.

Adhesins, Escherichia coli↗
PubMed1996

Relative significance of mannose-sensitive hemagglutinin and toxin-coregulated pili in colonization of infant mice by Vibrio cholerae El Tor.

A previously described in-frame deletion in mshA--the gene encoding the structural subunit of the mannose-sensitive hemagglutinin pilus--has been introduced into the chromosome of three El Tor O1 strains of Vibrio cholerae. None of the deltamshA mutants showed significant attenuation or loss of colonization potential in the infant mouse cholera model. A second mutation, created by insertion of a kanamycin resistance cartridge into deltamshA, also failed to affect in vivo behavior. In contrast, strains carrying mutations in tcpA (encoding the monomer of the toxin-coregulated pilus [TCP]) were markedly attenuated and showed dramatically impaired colonization. This result was in line with those of previous studies. Protection tests performed with antibodies to TCP and to MshA showed that only the former were able to confer immunity against El Tor O1 challenge in this model. Studies with mutants constructed from two O139 strains similarly suggest that TCP but not mannose-sensitive hemagglutinin pili are critical for colonization by strains of this serogroup.

Animals↗
PubMed1996

Immune mechanisms and protective antigens of Vibrio cholerae serogroup O139 as a basis for vaccine development.

We have characterized 11 isolates of Vibrio cholerae O139 Bengal with regard to properties deemed to be relevant for development of a vaccine against O139 cholera. For most strains two colony variants, A and B, which are nonhemolytic and hemolytic, respectively, were detected on blood agar. The A and B variants were associated with high- and low-level production of soluble hemagglutinin-protease, respectively. However, on Luria-Bertani agar both types formed opaque colonies, which has been shown to be associated with capsule formation. Interestingly, under the stationary tube-shaken flask culture conditions in yeast extract-peptone water medium which were used to stimulate the production of cholera toxin (CT) and toxin-coregulated pili, B variants constitutively produced CT and TcpA, two ToxR-regulated proteins, at 28 and 37 degrees C, whereas the production of these proteins by A variants was downregulated at the higher temperature. One of the strains, 4260B, having a well-exposed O antigen and capsule and the capacity to produce large amounts of TcpA, CT, and mannose-sensitive hemagglutinin pili but minimal amounts of the proteolytic soluble hemagglutinin, was selected to produce antibacterial antisera and as a challenge strain in protection studies using the rabbit ileal loop model. Rabbit antisera to live, heat-killed, or formalin-killed O139 vibrios or to purified O139 lipopoly-saccharide (LPS) as well as monoclonal antibodies (MAbs) to O139 LPS agglutinated all O139 isolates. However, when A and B variants of strain 4260 were tested for sensitivity to vibriocidal activity of these antibody preparations, only the B variant was killed. All of the antisera against live or killed O139 vibrios conferred passive protection against fluid accumulation induced by the challenge strain. The protective effects of the antisera were correlated to anti-LPS antibody titers rather than to titers against whole bacteria that had been grown for toxin-coregulated pilus expression. This protection was considerably higher than that conferred by antisera to classical, EI Tor, or recombinantly produced (classical) CT or CTB. Furthermore, MAbs to O139 LPS and CTB-CT exhibited a strong synergistic protection against O139 challenge irrespective of the level of sensitivity of challenge strains to O139 LPS MAbs in vibriocidal assays in vitro.

Animals↗
PubMed1994

Cloning and sequencing of Vibrio cholerae mannose-sensitive haemagglutinin pilin gene: localization of mshA within a cluster of type 4 pilin genes.

The mannose-sensitive haemagglutinin (MSHA) pilus that is associated with Vibrio cholerae strains of El Tor biotype has been shown to be a potential colonization factor and protective antigen. The gene encoding the structural subunit of MSHA pili was cloned from size-fractionated SacI-cleaved chromosomal DNA in the expression phage vector lambda ZAPII. Positive clones carried a c. 5.3 kb SacI fragment and were identified on the basis of MSHA expression and hybridization with a synthetic oligonucleotide probe based upon the N-terminus of MshA, the structural subunit of MSHA. The mshA gene was localized to a 2.6 kb SalI-EcoRI fragment, which was subcloned and shown to express MshA from its own promoter in Escherichia coli. Nucleotide sequencing of the entire fragment revealed six open reading frames (ORFs) of which four were complete. The mshA gene encodes an 18,094 Da prepilin protein, which in its mature form has a size of 17,436 Da. MshA is a type 4 (N-MePhe) pilin protein that is more homologous to pilins produced by Pseudomonas aeruginosa and Neisseria gonorrhoeae than to TcpA, the structural subunit of the toxin-coregulated pilus of V. cholerae. The protein seems to be directly involved in receptor binding, as an in-frame mutation in the mshA gene was found to abolish both D-mannose-dependent haemagglutination and binding of V. cholerae bacteria to D-mannose-containing agarose beads. Three additional ORFs, all in the same transcriptional orientation as mshA, were found to encode type 4 pilin-like proteins. A potential promoter with a sequence homologous to that of cAMP-CRP-activated promoters in E. coli was identified upstream of ORF3, the gene preceding mshA.

Amino Acid Sequence↗
PubMed1994

The maltose regulon of Vibrio cholerae affects production and secretion of virulence factors.

The effects of maltose on production and secretion of virulence factors of Vibrio cholerae in strain X28214, classical biotype, and in maltose-defective transposon mutants constructed from this strain were characterized. Maltose was found to inhibit secretion of cholera toxin and to reduce production of the mannose-sensitive hemagglutinin and the soluble hemagglutinin-protease. In contrast, the amount of toxin-coregulated pilus was increased in the presence of maltose. The maltose effect was apparently mediated by genes of the maltose regulon, since inactivation of the malQ or malF gene of V. cholerae by transposon insertion was found to affect production and secretion of the same virulence factors that were responsive to maltose. The malQ and malF mutants showed, in addition, reduced virulence in an infant-mouse model. These results suggest that maltose may have a significant regulatory role in the production of virulence factors and that an intact maltose regulon is needed for full virulence of V. cholerae.

Animals↗
PubMed1994

Role of antibodies against biotype-specific Vibrio cholerae pili in protection against experimental classical and El Tor cholera.

Vibrio cholerae O1, which exists as two biotypes, classical and El Tor, expresses fimbrial antigens called toxin-coregulated pili (TCP) and mannose-sensitive hemagglutinin (MSHA) pili, respectively. We have raised rabbit antisera and monoclonal antibodies against these fimbrial antigens and prepared Fab fragments which possess specific antibodies directed against the respective fimbrial antigens from these antisera. The protective effect of these antibody preparations was studied in the infant mouse cholera model. Antibodies against TCP were able to protect baby mice against challenge with V. cholerae O1 of the classical but not of the El Tor biotype. Similar but reverse biotype differences in protection against challenge with classical and El Tor vibrios were observed when antibodies against MSHA pili were used. The protective effect of V. cholerae O1 antilipopolysaccharide (anti-LPS) antibodies, both alone and in combination with antifimbrial antibodies, was also evaluated. We showed that antibodies to the LPS component also prevented infections with V. cholerae O1. Moreover, our results indicate that antibodies against TCP or MSHA pili and against LPS cooperate at least additively, and possible even synergistically, in protecting baby mice against challenge with group O1 vibrios. These results indicate that TCP and MSHA pili as well as LPS play an important role in the pathogenesis of experimental cholera. We could also demonstrate that antibacterial immunity preventing colonization is biotype specific. Our results might be used for the generation of new oral cholera vaccines including both TCP and MSHA fimbrial antigens.

Animals↗
PubMed1992

Enzyme-linked immunosorbent assay for determination of antibodies to Vibrio cholerae toxin-coregulated pili.

An ELISA for determination of antibodies to V. cholerae TCP was developed. Since purified TCP preparations contained detectable amounts of LPS (as shown by ELISA and immunoelectron microscopy with anti-LPS polyclonal serum), a capture ELISA was used. In this test the plate was coated with anti-TCP monoclonal antibody followed by incubation with TCP fimbriae. By this procedure no LPS bound to the solid phase as shown by the loss of reactivity with anti-LPS serum. The capture ELISA allowed sensitive and specific determination of TCP antibodies in sera of rabbits immunized with classical but not El Tor V. cholerae strains. There was good agreement between results in the TCP ELISA and reactivity with the TcpA band in immunoblot analyses when antisera raised against classical and El Tor vibrios were studied.

Animals↗
PubMed1992

Analysis of expression of toxin-coregulated pili in classical and El Tor Vibrio cholerae O1 in vitro and in vivo.

The expression of toxin-coregulated pili (TCP) and their structural subunit TcpA was compared in 20 strains of Vibrio cholerae of the classical and El Tor biotypes. Bacteria were isolated from the intestines of rabbits with experimental cholera and compared with the same strains grown under optimal TCP expression conditions in vitro. Immunoblotting revealed that TcpA production was induced in both biotypes after vibrios entered the intestinal milieu; TcpA-negative inocula gave rise to TcpA-positive vibrios after multiplication in the gut. The levels of TcpA expressed during growth in the intestine were, for most strains, comparable to those attained under optimal growth conditions in vitro. Of 11 classical strains tested, 10 expressed TCP antigen on the bacterial surface at levels comparable to or exceeding those seen after growth in vitro as determined by an inhibition enzyme-linked immunosorbent assay. In contrast, only one of the nine El Tor strains studied produced detectable amounts of TCP surface antigen in vivo and no fimbriae or surface antigen reacting with anti-TCP serum was found on El Tor vibrios from human cholera stools. Distinct TCP fimbriae were observed by immunoelectron microscopy on classical-biotype vibrios grown either in rabbit intestines or in vitro but were not detected on El Tor vibrios. The results show that TCP is expressed on V. cholerae O1 of the classical biotype but not on V. cholerae O1 of the El Tor biotype in the intestines of rabbits with experimental cholera infection.

Animals↗
PubMed1991

Identification of a mannose-binding pilus on Vibrio cholerae El Tor.

The mannose-sensitive hemagglutinin (MSHA) that is associated with Vibrio cholerae strains of El Tor biotype is identified as a pilus composed of subunits with a molecular mass of approximately 17 kDa. In immunoelectron microscopy, a monoclonal antibody against MSHA that inhibited El Tor vibrio-mediated mannose-sensitive agglutination of chicken erythrocytes or El Tor bacterial binding to mannose-coated agarose beads, bound specifically to repetitive subunits along typical fimbriae extending from the surface of El Tor vibrios. No such pili were seen on the surface of MSHA negative classical vibrios, although non-surface exposed fimbrial subunits could be demonstrated in these bacteria by immunoblotting techniques.

Antibodies, Monoclonal↗
PubMed1991

Epitope differences in toxin-coregulated pili produced by classical and El Tor Vibrio cholerae O1.

A toxin-coregulated pilus (TCP), that is important for intestinal colonization of Vibrio cholerae O1, may be produced by vibrios of both classical and EI Tor biotypes. By comparing TCP produced by various strains of the two biotypes in immunoblotting and enzyme-linked immunosorbent assays (ELISA) using monoclonal antibodies (mAbs) and polyclonal antisera against TCP from classical vibrios, we have found biotype-related epitope differences in TCP. Our results indicate that TCP of classical strains has an epitope in the TcpA-subunit (20.5 kDa) that is missing in EI Tor TcpA, and an additional epitope that is more strongly expressed in classical TcpA. A polyclonal antiserum reacted strongly with TcpA from strains of both biotypes in immunoblotting suggesting both the presence of major shared TcpA epitopes and that the low or absent reactivity of EI Tor TcpA with the mAbs was not due to lower production of TcpA by EI Tor strains. Whereas all the TcpA-positive classical strains inhibited the binding of polyclonal antiserum and mAbs to solid phase-bound TCP-positive bacteria in an inhibition ELISA, practically no inhibition was observed with TcpA-positive EI Tor strains. This together with findings in immunoelectron microscopy studies that TCP 'bundles' were only detected on classical strains, suggest that TCP is poorly expressed on EI Tor vibrios.

Blotting, Western↗
PubMed1991

Cystic duct remnants and biliary symptoms after cholecystectomy. A randomised comparison of two operative techniques.

To assess the importance of cystic duct remnants in causing biliary symptoms after cholecystectomy 80 patients undergoing routine cholecystectomy were randomised to have conventional cholecystectomy (n = 40) or cholecystectomy with removal of the whole cystic duct (n = 40). Fifteen were withdrawn, leaving 65 (32 who had standard cholecystectomy and 33 who had cholecystectomy by the new technique) for analysis. Thirty of the 32, and 27 of the 33, were available for follow up one, two, three, and eight years after operation; 11 of the 30 (37%) compared with 23 of the 27 (85%) were free of biliary symptoms during the eight year period (p less than 0.001). We conclude that removal of the stump of the cystic duct improves the success rate of cholecystectomy in the treatment of gallstones.

Abdominal Pain↗
PubMed1990

Binding of bacteria to carbohydrates immobilized on beads to demonstrate the presence of cell-associated hemagglutinins in Vibrio cholerae.

We describe a phase contrast microscopy method for direct observation of classical and El Tor vibrios to agarose beads containing covalently attached L-fucose or D-mannose. Binding of the vibrios to L-fucose beads was found to correlate with fucose-sensitive agglutination of human O erythrocytes, while binding of bacteria to beads with D-mannose was consistent with mannose-sensitive agglutination of chicken erythrocytes. Furthermore, vibrios expressing both fucose and mannose-sensitive hemagglutinins adhered equally to L-fucose and D-mannose-containing beads. Because this procedure is neither subject to biological variations in different populations of erythrocytes nor affected by other factors known to interfere with hemagglutination tests, it offers a suitable, more robust and specific alternative to detect functional adhesins in Vibrio cholerae and other bacteria.

Bacteria↗
PubMed1990

Interferon production by Shigella flexneri-infected fibroblasts depends upon intracellular bacterial metabolism.

The role of bacterial invasion and subsequent intracellular metabolism or replication, or both, in the induction of interferon (IFN) production in primary cultures of murine embryo fibroblasts (MEFs) was examined. IFN production appeared to be dependent upon bacterial invasion. MEFs that were challenged with Shigella flexneri cultured at 30 degrees C to inhibit the temperature-dependent virulence gene expression that is essential for invasion failed to produce IFN. Furthermore, inhibition of S. flexneri invasion by pretreatment of MEFs with cytochalasin B resulted in a reduction in IFN production. Intracellular bacterial residence alone, however, was not sufficient for the induction of IFN production since an avirulent isogenic variant of S. flexneri which invades but fails to grow intracellularly did not induce IFN production. In fact, the blocking of bacterial RNA synthesis immediately after cellular uptake of S. flexneri by rifampin inhibited IFN production by MEFs. Transfer of the invasion-encoding plasmid to a noninvasive Escherichia coli strain conferred upon the bacteria the ability to invade MEFs and induce IFN production. These results suggest that the induction of IFN production in S. flexneri-infected fibroblasts requires bacterial invasion and intracellular bacterial metabolism or replication, or both.

Animals↗