Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An international collaborative study was conducted at ten sites to examine the performance of enzyme immunoassays (EIAs) for the quantitation of IgG1, IgG2, IgG3, IgG4 and total IgG anti-Haemophilus influenzae type b (Hib) capsular polysaccharide in human serum. All groups used the same reagents: microtiter plates coated with polyribosylribitol phosphate (PRP) conjugated to poly-L-lysine (PLL), reference, control and test human sera, biotin-conjugated International Union of Immunological Societies (IUIS)-documented monoclonal anti-human IgG1-4 and IgG Pan detection antibodies, avidin-peroxidase and TMB substrate. Initial mixing of soluble PRP antigen or an equal volume of buffer with the 20 test sera prior to analysis confirmed PRP antigen specificity in all five EIAs with greater than 80% competitive inhibition at most sites. Positive correlation between the total IgG anti-Hib and sum of IgG1-4 anti-Hib was demonstrated (r2 = 0.99, Y = 1.13X -0.15). Good agreement was shown between the total IgG anti-Hib as measured by EIA and the total Hib-specific antibodies measured by the current radiolabeled antigen binding assay (r2 = 0.97, Y = 4.6X -5.8). Assay parallelism was demonstrated with an average interdilutional %CV of 22% and parallel dose-response curve slopes. The interdilutional %CVs were calculated as an average per sample of the variation of microgram/ml (corrected for dilution) at different dilutions per laboratory for all participating sites. The interlaboratory variation was the only performance parameter studied that exceeded the target level of 35% CV in all IgG1-4 and total IgG anti-Hib assays. IgG subclass distributions in the test sera demonstrated a predominance of IgG1 anti-Hib in the pediatric serum pools and IgG2 anti-Hib in the adult sera, with low but detectable levels of IgG3 and IgG4 anti-Hib in each group.
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PMID:Quantitation of human IgG subclass antibodies to Haemophilus influenzae type b capsular polysaccharide. Results of an international collaborative study using enzyme immunoassay methodology. 156 20

The specificity by which Haemophilus species acquired iron from transferrin (TF) was investigated. In a plate bioassay H. influenzae used iron bound to human, bovine and rabbit TFs but not mouse, rat, dog, horse, guinea-pig, pig or ovo- TFs or human and bovine lactoferrins. In contrast, H. pleuropneumoniae used iron only from pig TF whilst H. parainfluenzae was unable to utilize iron bound to any of the human or animal TFs tested. The inhibition of growth imposed on H. influenzae type b strain Eagan by the addition of the synthetic iron chelator EDDA to the culture medium was reversed by 30% iron-saturated human TF added directly to the medium but not when the TF was contained inside a dialysis bag. Dot-blotting of whole cells revealed that human TF bound to the surface of bacteria cultured in iron-restricted but not in iron-plentiful media. Incubation of whole bacterial cells in the presence of the proteolytic enzyme trypsin also abolished TF-binding activity, suggesting that the TF receptor was a protein. In competition dot blotting experiments, human and bovine but not rabbit, dog, mouse or guinea-pig TFs blocked the binding of a horseradish peroxidase--human TF conjugate. SDS-PAGE and Western blotting of outer membranes revealed the presence of a TF-binding protein of approximately 72 kDa. These results suggest that the acquisition of TF-bound iron by H. influenzae type b probably involves a direct interaction with an outer-membrane protein which shows some TF-species specificity.
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PMID:Siderophore-independent acquisition of transferrin-bound iron by Haemophilus influenzae type b. 214 16

Nine clinical isolates of Haemophilus somnus were screened for their ability to use different transferrins as a source of iron growth. All nine strains were capable of using bovine but not porcine, human or chicken transferrin. A screening assay for siderophore production did not show any evidence of siderophore production by these strains. When iron-deficient cells from these strains were screened for their ability to bind peroxidase-conjugated transferrin, binding was detected with conjugated bovine, but not human or porcine transferrin. Competition binding studies demonstrated that the binding of peroxidase-conjugated bovine transferrin was competitively inhibited by unconjugated bovine transferrin but not transferrin from other species. The induction of receptor expression by low iron conditions was inhibited by chloramphenicol and rifampicin but not ampicillin indicating that new protein and mRNA synthesis was required for expression of receptor activity. Affinity isolation of receptor proteins with biotinylated bovine transferrin, but not human or porcine transferrin, yielded three proteins from H. somnus strain H74. Two of the proteins were identified as 105 kDa and 73 kDa iron-regulated outer membrane proteins. A third protein of 85 kDa that was isolated did not co-migrate with any iron-regulated outer membrane protein. Affinity isolation of receptor proteins from other strains of H. somnus yielded a 73 kDa protein from all strains and a 105 kDa and 85 kDa protein in four of the six strains analysed.
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PMID:Response of Haemophilus somnus to iron limitation: expression and identification of a bovine-specific transferrin receptor. 215 61

To characterize the bovine immune response to an Haemophilus somnus antigen known to be recognized by convalescent-phase serum, we studied isotypic antibody titers to the 270-kilodalton protein, which we had previously shown to be an immunoglobulin Fc receptor. With a modified immunodot procedure, an immune response was detected after experimental H. somnus abortion, experimental H. somnus pneumonia, or vaccination with commercial H. somnus vaccine, with the greatest titer found within the immunoglobulin G2 isotype. With protein A peroxidase conjugate, which detects primarily bovine immunoglobulin G2, we showed that cattle with H. Somnus disease could be distinguished from clinically normal carriers, culture-negative cattle, or cattle with disease due to Pasteurella haemolytica or P. multocida. Little cross-reactivity between the 270-kilodalton Fc receptor antigen and antigens from other gram-negative bovine pathogens was seen. Thus, this antigen may be a useful diagnostic antigen.
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PMID:Antibody response to Haemophilus somnus Fc receptor. 264 14

The expression of human transferrin and lactoferrin binding activity in Haemophilus influenzae, detected by a binding assay using human transferrin or lactoferrin conjugated to peroxidase, was regulated by the level of available iron in the medium. Transferrin binding activity was present in all H. influenzae isolates tested but not detected in other Haemophilus species or in species of Pasteurella or Actinobacillus. Lactoferrin binding activity was only detected in 1/15 H. influenzae isolates tested. The transferrin and lactoferrin receptors were shown to be specific for the respective human proteins by means of a competition binding assay. Competition binding assays also showed that iron-loaded transferrin was more effective at blocking the transferrin receptor than apotransferrin, but no differences in receptor blocking were observed between iron-loaded lactoferrin and apolactoferrin.
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PMID:Characterization of the human transferrin and lactoferrin receptors in Haemophilus influenzae. 284 24

The antigens of Haemophilus somnus recognized by convalescent bovine serum were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting with a protein A-peroxidase conjugate. The same two 76K and 40K antigens were predominant in whole-bacterium preparations and in outer-membrane-enriched, Triton X-100-insoluble fractions. The surface location of these two antigens was confirmed by absorbing antiserum with whole, live bacteria. Absorption with H. somnus removed antibody reactivity for the 76K antigen and reduced reactivity for the 40K antigen. Absorption with Pasteurella multocida, Actinobacillus equuli, or Escherichia coli did not reduce reactivity, and results with Pasteurella haemolytica were equivocal. The two immunodominant antigens detected in this study were conserved in isolates of H. somnus from thromboembolic meningoencephalitis, pneumonia, reproductive failure, or asymptomatic carriers. Convalescent sera from nearly all 17 cattle studied recognized these two antigens. Other antigens were recognized less consistently. Although other antigens may also be involved, the 76K and 40K surface antigens of H. somnus appear to be important candidates for a subunit vaccine or an immunodiagnostic assay.
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PMID:Antigenic specificity of convalescent serum from cattle with haemophilus somnus-induced experimental abortion. 357 Apr 70

The sensitivity and performance characteristics of enzyme immunoassays (EIA) depend to a great extent on the kinetics of the enzyme-substrate system used as indicator. We labeled a variety of polyclonal and monoclonal immunoglobulins with purified beta-lactamase and used them in sensitive EIA systems for the detection of a number of microbial antigens. Polyclonal antibodies to rotavirus, adenovirus, and Haemophilus influenzae type b polyribitol phosphate and monoclonal antibodies to dengue virus were labeled with beta-lactamase and used to provide sensitive direct EIA systems for the detection of the corresponding antigens. In addition, antibodies directed at animal immunoglobulins were labeled with beta-lactamase and used in indirect EIA for the detection of viral antigens with unlabeled anti-viral monoclonal and polyclonal antibodies. Similarly, avidin from Streptomyces was labeled with beta-lactamase and used to detect viral antigens tested for in an avidin-biotin format. Enzyme immunoassay systems with beta-lactamase-labeled antibodies were also used to detect rotaviral and adenoviral antigens in rectal swab specimens from children with acute gastroenteritis. The sensitivity of the beta-lactamase EIA compared favorably with that of analogous EIA systems using alkaline phosphatase or horseradish peroxidase. The results of a beta-lactamase EIA were easily determined by naked eye and a permanent record of the qualitative results obtained by the use of a standard office photocopier, obviating the need for an expensive colorimeter. Enzyme immunoassays using beta-lactamase have potential as practical assay systems for the detection of a wide range of microbial antigens using monoclonal and polyclonal antibodies.
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PMID:The use of beta-lactamase in enzyme immunoassays for detection of microbial antigens. 609 74

This report describes the use of peroxidase-labeled staphylococcal protein A to prepare conjugates suitable for direct enzyme immunoassays (EIAs). Such conjugates were used to develop direct EIA systems for the measurement of two antigens associated with human infections, human rotavirus and Haemophilus influenzae type b polysaccharide. Both systems were as sensitive or more sensitive than currently available EIAs for the measurement of standard antigens. In addition, both systems could be utilized to correctly identify the antigens in clinical specimens obtained from sick patients. Efficient enzyme conjugates prepared with enzyme-labeled staphylococcal protein A were simple to formulate providing that immunoglobulin of the appropriate animal species was available as the source of antibody. The use of such conjugates might increase the availability of practical EIA systems for the measurement of a wide range of medically important antigens.
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PMID:Staphylococcal protein A-enzyme immunoglobulin conjugates: versatile tools for enzyme immunoassays. 626 38

A heterogeneous enzyme immunoassay (EIA) has been developed to quantify capsular polysaccharide antigen of Haemophilus influenzae serotype b (Hib) polyribosyl - polyribitol -phosphate (PRP) in body fluids. Anti-Hib immunoglobulin G form rabbit adsorbed to the solid phase reacts with PRP existing in free soluble form in cerebrospinal fluid, serum or urine during Hib infection. IgG-anti-Hib labelled with horseradish peroxidase then links to PRP; the enzyme activity is measured by oxidation of the chromogenic substrate o-phenylenediamine. PRP concentrations ranged between 2 micrograms/1 to 21 mg/1 detected in acute Hib disease. The applicability of the EIA as a diagnostic aid is limited by cross-reaction of other bacterial antigens. However, quantitative measurements of PRP by enzyme immunoassay should improve studies on Hib disease.
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PMID:Quantitation of Haemophilus influenzae serotype b capsular polysaccharide antigen in body fluids by enzyme immunoassay. 637 94

A direct sandwich enzyme-linked immunosorbent assay (ELISA) was developed to detect Haemophilus influenzae type b capsular antigen. Using polystyrene as the solid phase and peroxidase-labelled rabbit antibody the assay detected the antigen in concentrations of 0.1 ng/ml. Linearity was achieved within the range of 1ng to 10 microgram/ml. Subtle measurements of Haemophilus influenzae type b capsular antigen in body fluids are possible through ELISA which is superior to counterimmunoelectrophoresis and latex-particle agglutination in this respect. ELISA should facilitate investigations concerning PRP pathogenic effects in experimental Hib infection as well as in human Hib disease.
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PMID:Haemophilus influenzae type b capsular polysaccharide detection and measurement by an enzyme-linked immunosorbent assay (ELISA). 701 64


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