scholarly journals Factor H-Binding Protein Is Important for Meningococcal Survival in Human Whole Blood and Serum and in the Presence of the Antimicrobial Peptide LL-37

2008 ◽  
Vol 77 (1) ◽  
pp. 292-299 ◽  
Author(s):  
K. L. Seib ◽  
D. Serruto ◽  
F. Oriente ◽  
I. Delany ◽  
J. Adu-Bobie ◽  
...  
Keyword(s):  
Antimicrobial Peptide ◽  
Human Blood ◽  
Whole Blood ◽  
Electrostatic Interactions ◽  
Binding Protein ◽  
Alternative Pathway ◽  
Factor H ◽  
Phase Iii ◽  
Human Whole Blood ◽  
Mutant Strains

ABSTRACT Factor H-binding protein (fHBP; GNA1870) is one of the antigens of the recombinant vaccine against serogroup B Neisseria meningitidis, which has been developed using reverse vaccinology and is the basis of a meningococcal B vaccine entering phase III clinical trials. Binding of factor H (fH), an inhibitor of the complement alternative pathway, to fHBP enables N. meningitidis to evade killing by the innate immune system. All fHBP null mutant strains analyzed were sensitive to killing in ex vivo human whole blood and serum models of meningococcal bacteremia with respect to the isogenic wild-type strains. The fHBP mutant strains of MC58 and BZ83 (high fHBP expressors) survived in human blood and serum for less than 60 min (decrease of >2 log10 CFU), while NZ98/254 (intermediate fHBP expressor) and 67/00 (low fHBP expressor) showed decreases of >1 log10 CFU after 60 to 120 min of incubation. In addition, fHBP is important for survival in the presence of the antimicrobial peptide LL-37 (decrease of >3 log10 CFU after 2 h of incubation), most likely due to electrostatic interactions between fHBP and the cationic LL-37 molecule. Hence, the expression of fHBP by N. meningitidis strains is important for survival in human blood and human serum and in the presence of LL-37, even at low levels. The functional significance of fHBP in mediating resistance to the human immune response, in addition to its widespread distribution and its ability to induce bactericidal antibodies, indicates that it is an important component of the serogroup B meningococcal vaccine.

scholarly journals OBSERVATIONS ON THE PHAGOCYTOSIS OF THE PNEUMOCOCCUS BY HUMAN WHOLE BLOOD

1930 ◽  
Vol 51 (5) ◽  
pp. 675-684 ◽  
Author(s):  
Hugh K. Ward
Keyword(s):  
Human Blood ◽  
Whole Blood ◽  
Type I ◽  
Human Whole Blood ◽  
Type Iii ◽  
Number Of Individuals ◽  
Considerable Range

1. The phagocytic titre of whole human blood against the three types of pneumococcus was determined in a number of individuals. The titre varied over a considerable range in different subjects. 2. Contrary to expectation, the titre in early cases of untreated pneumonia was quite high against the infecting organism, pointing to a local rather than a general lowering of resistance in infection with this organism. 3. Sia's work was confirmed, that the specific carbohydrate has a specific anti-phagocytic action on the blood. This action is more marked in the case of Type III than in Type I.

scholarly journals The Hyphal and Yeast Forms of Candida albicans Bind the Complement Regulator C4b-Binding Protein

2004 ◽  
Vol 72 (11) ◽  
pp. 6633-6641 ◽  
Author(s):  
T. Meri ◽  
A. M. Blom ◽  
A. Hartmann ◽  
D. Lenk ◽  
S. Meri ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Confocal Microscopy ◽  
Binding Site ◽  
Binding Protein ◽  
Alternative Pathway ◽  
Factor H ◽  
Enzyme Linked Immunosorbent Assay ◽  
Classical Pathway ◽  
Pathogenic Yeast ◽  
Yeast Surface

ABSTRACT Candida albicans, an important pathogenic yeast, activates all three pathways of the complement system. To understand how this yeast evades the effects of the activated system, we have analyzed the binding of the classical pathway inhibitor C4b-binding protein (C4BP) by C. albicans. Purified native as well as recombinant C4BP bound dose dependently to the yeast and hyphal forms, as shown by multiple methods, such as confocal microscopy, flow cytometry, a novel enzyme-linked immunosorbent assay, absorption from human serum, and direct binding assays with purified proteins. A prominent binding site was identified at the tip of the germ tube, a structure that is considered important for tissue penetration and pathogenesis. The binding site in C4BP was localized to the two N-terminal complement control protein domains by using recombinant deletion constructs and site-specific monoclonal antibodies. As the alternative pathway inhibitors factor H and FHL-1 also bind to C. albicans, the binding of all three plasma proteins was compared. Simultaneous binding of the classical regulator C4BP and the alternative pathway regulator factor H was demonstrated by confocal microscopy. In addition, FHL-1 competed for binding with C4BP, suggesting that these two related complement regulators bind to the same structures on the yeast surface. The surface-attached C4BP maintains its complement regulatory activities and inactivates C4b. The surface-attached human C4BP serves multiple functions relevant for immune evasion and likely pathogenicity. It inhibits complement activation at the yeast surface and, in addition, mediates adhesion of C. albicans to host endothelial cells.

Metabolism of 75Se-selenite by human whole blood in vitro

1969 ◽  
Vol 47 (8) ◽  
pp. 791-797 ◽  
Author(s):  
Melvin Lee ◽  
Alice Dong ◽  
Joyce Yano
Keyword(s):  
Plasma Protein ◽  
Human Blood ◽  
Release Rate ◽  
Whole Blood ◽  
Human Whole Blood ◽  
First Order ◽  
First Order Kinetics ◽  
Altered Form

When 75Se, as selenite, is added to human blood it is rapidly taken up by the cells (50–70% within 1–2 min) and is then released into the plasma so that most of the radioactivity is in the plasma by 15–20 min. Uptake is inhibited by 10−3 M cyanide. The release of radioactivity from the cells is inhibited by 10−3 M para-chloromercuribenzoate and by 10−3 M iodoacetamide, although these agents do not affect uptake. Azide and 2,4-dinitrophenol (at 10−3 M) do not affect either process. Large quantities of sulfite, sulfate, and selenate (1000 times as much S or Se as 75Se) do not affect uptake or release, but large amounts of selenite (1000 times) inhibit release. The release rate follows first-order kinetics and increases with temperature. 75Se released from cells is bound by a plasma protein but can be removed from the protein by treatment with cysteine. Studies suggest that the released selenium is in an altered form or state, although this product has not been characterized. A hypothetical pathway for the metabolism of selenium is presented to account for the observations.

Human whole-blood oxygen affinity: effect of temperature

1984 ◽  
Vol 57 (2) ◽  
pp. 429-434 ◽  
Author(s):  
A. Zwart ◽  
G. Kwant ◽  
B. Oeseburg ◽  
W. G. Zijlstra
Keyword(s):  
Whole Blood ◽  
Oxygen Affinity ◽  
Heat Evolution ◽  
Factor H ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Human Whole Blood ◽  
Healthy Donors ◽  
Blood Oxygen Affinity ◽  
O2 Dissociation Curve

phe effect of temperature changes on human whole-blood O2 affinity was measured in the blood of six healthy donors over almost the entire O2 saturation (SO2) range (1–99%). The results showed that temperature has no influence on the shape of the O2 dissociation curve, implying that the temperature coefficient (delta log PO2/delta T) is independent of SO2. Simultaneous measurements of the total (proton) Haldane factor (delta[HbH]/[delta HbO2]) at the five temperatures under study (22, 27, 32, 37, and 42 degrees C) revealed that this factor depends on temperature. The liberation of protons from hemoglobin appeared to be linear with respect to changes in SO2. We therefore conclude that the (proton) Bohr factor (H+ factor) is dependent on temperature over the entire SO2 range in the same way as previously described for SO2 = 50%. The exothermic oxygenation reaction in whole blood was accompanied by a heat evolution (delta HO2) of 42.7 kJ/mol (monomeric) hemoglobin.

scholarly journals Neisseria cinerea Expresses a Functional Factor H Binding Protein Which Is Recognized by Immune Responses Elicited by Meningococcal Vaccines

2017 ◽  
Vol 85 (10) ◽  
Author(s):  
Hayley Lavender ◽  
Katy Poncin ◽  
Christoph M. Tang
Keyword(s):  
Capsular Polysaccharide ◽  
Binding Protein ◽  
Alternative Pathway ◽  
Factor H ◽  
Recent Analysis ◽  
Complement Factor ◽  
Content Type ◽  
Commensal Flora ◽  
Commensal Species ◽  
Complement Regulator

ABSTRACT Neisseria meningitidis is a major cause of bacterial meningitis and sepsis worldwide. Capsular polysaccharide vaccines are available against meningococcal serogroups A, C, W, and Y. More recently two protein-based vaccines, Bexsero and Trumenba, against meningococcal serogroup B strains have been licensed; both vaccines contain meningococcal factor H binding protein (fHbp). fHbp is a surface-exposed lipoprotein that binds the negative complement regulator complement factor H (CFH), thereby inhibiting the alternative pathway of complement activation. Recent analysis of available genomes has indicated that some commensal Neisseria species also contain genes that potentially encode fHbp, although the functions of these genes and how immunization with fHbp-containing vaccines could affect the commensal flora have yet to be established. Here, we show that the commensal species Neisseria cinerea expresses functional fHbp on its surface and that it is responsible for recruitment of CFH by the bacterium. N. cinerea fHbp binds CFH with affinity similar to that of meningococcal fHbp and promotes survival of N. cinerea in human serum. We examined the potential impact of fHbp-containing vaccines on N. cinerea. We found that immunization with Bexsero elicits serum bactericidal activity against N. cinerea, which is primarily directed against fHbp. The shared function of fHbp in N. cinerea and N. meningitidis and cross-reactive responses elicited by Bexsero suggest that the introduction of fHbp-containing vaccines has the potential to affect carriage of N. cinerea and other commensal species.

scholarly journals Functional Comparison of the Binding of Factor H Short Consensus Repeat 6 (SCR 6) to Factor H Binding Protein from Neisseria meningitidis and the Binding of Factor H SCR 18 to 20 to Neisseria gonorrhoeae Porin

2009 ◽  
Vol 77 (5) ◽  
pp. 2094-2103 ◽  
Author(s):  
Jutamas Shaughnessy ◽  
Lisa A. Lewis ◽  
Hanna Jarva ◽  
Sanjay Ram
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Neisseria Meningitidis ◽  
Binding Protein ◽  
Alternative Pathway ◽  
Factor H ◽  
Site Directed Mutagenesis ◽  
Chimeric Proteins ◽  
Inhibitory Protein ◽  
Protein Factor ◽  
Short Consensus Repeat

ABSTRACT Both Neisseria meningitidis and Neisseria gonorrhoeae recruit the alternative pathway complement inhibitory protein factor H (fH) to their surfaces to evade complement-dependent killing. Meningococci bind fH via fH binding protein (fHbp), a surface-exposed lipoprotein that is subdivided into three variant families based on one classification scheme. Chimeric proteins that comprise contiguous domains of fH fused to murine Fc were used to localize the binding site for all three fHbp variants on fH to short consensus repeat 6 (SCR 6). As expected, fH-like protein 1 (FHL-1), which contains fH SCR 6, also bound to fHbp-expressing meningococci. Using site-directed mutagenesis, we identified histidine 337 and histidine 371 in SCR 6 as important for binding to fHbp. These findings may provide the molecular basis for recent observations that demonstrated human-specific fH binding to meningococci. Differences in the interactions of fHbp variants with SCR 6 were evident. Gonococci bind fH via their porin (Por) molecules (PorB.1A or PorB.1B); sialylation of lipooligosaccharide enhances fH binding. Both sialylated PorB.1B- and (unsialylated) PorB.1A-bearing gonococci bind fH through SCR 18 to 20; PorB.1A can also bind SCR 6, but only weakly, as evidenced by a low level of binding of FHL-1 relative to that of fH. Using isogenic strains expressing either meningococcal fHbp or gonococcal PorB.1B, we discovered that strains expressing gonococcal PorB.1B in the presence of sialylated lipooligosaccharide bound more fH, more effectively limited C3 deposition, and were more serum resistant than their isogenic counterparts expressing fHbp. Differences in fH binding to these two related pathogens may be important for modulating their individual responses to host immune attack.

scholarly journals Meningococcal Factor H Binding Protein Vaccine Antigens with Increased Thermal Stability and Decreased Binding of Human Factor H

2016 ◽  
Vol 84 (6) ◽  
pp. 1735-1742 ◽  
Author(s):  
Raffaella Rossi ◽  
Monica Konar ◽  
Peter T. Beernink
Keyword(s):  
Thermal Stability ◽  
Binding Protein ◽  
Alternative Pathway ◽  
Factor H ◽  
Antibody Responses ◽  
Protein Vaccine ◽  
Wild Type ◽  
Complement Alternative Pathway ◽  
Content Type ◽  
Protective Antibody

Neisseria meningitidiscauses cases of bacterial meningitis and sepsis. Factor H binding protein (FHbp) is a component of two licensed meningococcal serogroup B vaccines. FHbp recruits the complement regulator factor H (FH) to the bacterial surface, which inhibits the complement alternative pathway and promotes immune evasion. Binding of human FH impairs the protective antibody responses to FHbp, and mutation of FHbp to decrease binding of FH can increase the protective responses. In a previous study, we identified two amino acid substitutions in FHbp variant group 2 that increased its thermal stability by 21°C and stabilized epitopes recognized by protective monoclonal antibodies (MAbs). Our hypothesis was that combining substitutions to increase stability and decrease FH binding would increase protective antibody responses in the presence of human FH. In the present study, we generated four new FHbp single mutants that decreased FH binding and retained binding of anti-FHbp MAbs and immunogenicity in wild-type mice. From these mutants, we selected two, K219N and G220S, to combine with the stabilized double-mutant FHbp antigen. The two triple mutants decreased FH binding >200-fold, increased the thermal stability of the N-terminal domain by 21°C, and bound better to an anti-FHbp MAb than the wild-type FHbp. In human-FH-transgenic mice, the FHbp triple mutants elicited 8- to 15-fold-higher protective antibody responses than the wild-type FHbp antigen. Collectively, the data suggest that mutations to eliminate binding of human FH and to promote conformational stability act synergistically to optimize FHbp immunogenicity.

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