Biomedical subjects

Arne Forsgren

Publications and source records attributed to Arne Forsgren.

At least 19 recordsLinked to original sources

PubMed2006

Purification of IgD from human serum--a novel application of recombinant M. catarrhalis IgD-binding protein (MID).

Moraxella catarrhalis IgD-binding protein (MID) is a multimeric outer membrane protein belonging to the family of autotransporters. The IgD-binding domain of MID is located between amino acids MID 962-1200 and binds to amino acids 198-224 of the IgD C(H)1 region. In the present study, we describe a method to purify IgD from serum with high levels of IgD using a two-step affinity chromatography process. The first step involves depletion of MID-specific antibodies of all classes from serum using the non-IgD-binding fragment MID(1000-1200). This step is followed by selective capture of IgD with MID(962-1200). Furthermore, we demonstrate that the eluted IgD is pure, intact and functional for use in downstream applications. Our approach reduces the non-specificity commonly associated with lectin-based IgD purification regimes that rely on glycosylation of the IgD molecule.

Adhesins, Bacterial↗

PubMed2006

Comparison of the serological responses to Moraxella catarrhalis immunoglobulin D-binding outer membrane protein and the ubiquitous surface proteins A1 and A2.

Moraxella catarrhalis immunoglobulin D-binding protein (MID) is a complex antigen with unique immunoglobulin D (IgD)-binding, adhesion, and hemagglutination properties. Previous studies have shown that antibodies raised against MID764-913 in rabbits inhibited M. catarrhalis adhesion to human alveolar epithelial cells, and immunization with MID764-913 resulted in an increased pulmonary clearance in a murine model. Strong immune responses against MID have also consistently been shown in humans. Here, the MID-specified IgG responses were compared to those of ubiquitous surface proteins A1 and A2 (UspA1/A2) using a series of recombinant fragments that spanned all three proteins. Sera were obtained from young children, aged 6 months to 1 year (n=8) and 2 to 3 years (n=15), and healthy adults (n=16). Acute- and convalescent-phase sera from chronic obstructive pulmonary disease (COPD) patients with M. catarrhalis infective exacerbations (n=23) were also analyzed. Young children, who are at risk of M. catarrhalis infection, had low levels of anti-MID and anti-UspA1/A2 antibodies. Healthy adults and the majority of COPD patients (16/23) had high levels of antibodies directed against, among others, the adhesive domain of MID and the fibronectin- and C3-binding domains of UspA1/A2. Among eight COPD patients in whom a rise in antibody levels could be detected, these functional domains were also the main regions targeted by the antibodies. In addition, human IgG directed against MID was bactericidal and anti-MID antibodies were additive to antibodies targeting UspA1/A2. Hence, the functional domains in these three antigens may have significant potential in a future vaccine against M. catarrhalis.

Adult↗

PubMed2006

MID and UspA1/A2 of the human respiratory pathogen Moraxella catarrhalis, and interactions with the human host as basis for vaccine development.

Moraxella catarrhalis IgD-binding protein MID is a 200 kDa autotransporter protein that exists as a oligomer and is governed at the transcriptional level. The majority of M. catarrhalis clinical isolates expresses MID. Two functional domains have been attributed to MID; MID764-913 functions as an adhesin and promotes the bacteria to attach to epithelial cells, whereas the IgD-binding domain is located within MID962-1200. In parallel, MID is stimulatory for B lymphocytes through the IgD B cell receptor. M. catarrhalis ubiquitous surface proteins A1 and A2 (UspA1/A2) are multifunctional outer membrane proteins that can bind complement and extracellular matrix proteins such as vitronectin and fibronectin. An interaction between the complement fluid phase regulator of the classical pathway, C4b binding protein (C4BP), and UspA1/A2 has also been observed. Moreover, UspA1/A2 has a unique feature to interfere with the innate immune system of complement by binding C3. Taken together, a growing body of knowledge on M. catarrhalis outer membrane proteins MID and UspA1/A2 and their precise interactions with the human host make them promising vaccine candidates in a future multicomponent vaccine.

Adhesins, Bacterial↗

PubMed2006

The respiratory pathogen moraxella catarrhalis binds to laminin via ubiquitous surface proteins A1 and A2.

Moraxella catarrhalis is one of the leading causes of exacerbations in chronic obstructive pulmonary disease (COPD). In the present article, we show that moraxella (n=15) binds to the major basement-membrane glycoprotein laminin, which is thickened in the airways of smokers. Using clinical strains of M. catarrhalis and their corresponding ubiquitous surface protein (Usp) A1/A2 mutants, we demonstrate that UspA1 and UspA2 are important for the laminin interaction. Binding assays with recombinant proteins demonstrated that the binding regions are localized within the N-terminal fragments, where both proteins form a globular head. Thus, UspA1/A2-dependent interactions with laminin might promote bacterial adhesion, particularly in smokers with COPD.

Bacterial Adhesion↗

PubMed2006

Haemophilus influenzae surface fibrils contribute to serum resistance by interacting with vitronectin.

Vitronectin inhibits the membrane attack complex of the complement system and is found both in plasma and the extracellular matrix. In this study, we have identified the outer membrane protein Haemophilus surface fibrils (Hsf) as the major vitronectin-binding protein in encapsulated H. influenzae type b. A H. influenzae mutant devoid of Hsf showed a significantly decreased binding to both soluble and immobilized vitronectin as compared with the wild-type counterpart. Moreover, Escherichia coli-expressing Hsf at the surface strongly adhered to immobilized vitronectin. Importantly, the H. influenzae Hsf mutant had a markedly reduced survival as compared with the wild-type bacterium when incubated with normal human serum. A series of truncated Hsf fragments were recombinantly manufactured in E. coli. The vitronectin binding regions were located within two separate binding domains. In conclusion, Hsf interacts with vitronectin and thereby inhibits the complement-mediated bactericidal activity, and thus is a major H. influenzae virulence factor.

Adhesins, Bacterial↗

PubMed2006

The IgD CH1 region contains the binding site for the human respiratory pathogen Moraxella catarrhalis IgD-binding protein MID.

The Moraxella catarrhalis IgD-binding protein (MID) has a unique specificity for human IgD, and the sequence with maximal IgD binding is located within the amino acids MID962-1200. In the present paper, we examined the MID binding site on IgD using a series of recombinant Ig. Full-length IgD, IgD F(ab')2, and an IgD F(ab') C290R mutant lacking the inter-heavy-chain cysteine 290 were manufactured. Furthermore, a series of IgD/IgG chimeras were constructed. ELISA, dot blot and flow cytometry were used to study the binding of purified Ig to native MID, recombinant MID962-1200 or to Moraxella with or without MID. MID962-1200 bound both the IgD F(ab')2 and F(ab') C290R, indicating that the binding occurred independently of antibody structure. When amino acids 157-224 of the IgD CH1 region were substituted with IgG sequences, binding by M. catarrhalis or recombinant MID962-1200 was abolished. Subsequent smaller substitutions of IgD CH1 157-224 with IgG sequences led us to conclude that IgD CH1 amino acids 198-206 were crucial for the interaction between MID and IgD.

Adhesins, Bacterial↗

PubMed2005

The IgD-binding domain of the Moraxella IgD-binding protein MID (MID962-1200) activates human B cells in the presence of T cell cytokines.

Moraxella catarrhalis immunoglobulin D (IgD)-binding protein (MID) is an outer membrane protein with specific affinity for soluble and cell-bound human IgD. Here, we demonstrate that mutated M. catarrhalis strains devoid of MID show a 75% decreased activation of human B cells as compared with wild-type bacteria. In contrast to MID-expressing Moraxella, the MID-deficient Moraxella mutants did not bind to human CD19+ IgD+ B cells. The smallest MID fragment with preserved IgD-binding capacity comprises 238 amino acids (MID(962-1200)). To prove the specificity of MID(962-1200) for IgD, a Chinese hamster ovary (CHO) cell line expressing membrane-anchored human IgD was manufactured. MID(962-1200) bound strongly to the recombinant IgD on CHO cells. Moreover, MID(962-1200) stimulated peripheral blood lymphocyte (PBL) proliferation 5- and 15-fold at 0.1 and 1.0 microg/ml, respectively. This activation could be blocked completely by antibodies directed against the CD40 ligand (CD154). MID(962-1200) also activated purified B cells in the presence of interleukin (IL)-2 or IL-4. An increased IL-6 production was seen after stimulation with MID(962-1200), as revealed by a human cytokine protein array. MID(962-1200) fused to green fluorescent protein (GFP) bound to human B cells and activated PBL to the same degree as MID(962-1200). Taken together, MID is the only IgD-binding protein in Moraxella. Furthermore, the novel T cell-independent antigen MID(962-1200) may, together with MID(962-1200)-GFP, be considered as promising reagents in the study of IgD-dependent B cell activation.

Adhesins, Bacterial↗

PubMed2005

Ionic binding of C3 to the human pathogen Moraxella catarrhalis is a unique mechanism for combating innate immunity.

Moraxella catarrhalis ubiquitous surface proteins A1 and A2 (UspA1/A2) interfere with the classical pathway of the complement system by binding C4b-binding protein. In this study we demonstrate that M. catarrhalis UspA1 and A2 noncovalently and in a dose-dependent manner bind both the third component of complement (C3) from EDTA-treated serum and methylamine-treated C3. In contrast, related Moraxella subspecies (n = 13) or other human pathogenic bacteria (n = 13) do not bind C3 or methylamine-treated C3. Experiments with recombinant proteins and M. catarrhalis mutants devoid of UspA1/A2 revealed that UspA1/A2 exert their actions by absorbing and neutralizing C3 from serum and restrain complement activation. UspA2 was responsible for most of the effect, and the Moraxella mutant lacking UspA2 was more sensitive to the lytic effect of human serum compared with the wild type. Interestingly, among the large number of bacteria analyzed, only M. catarrhalis has this unique ability to interfere with the innate immune system of complement by binding C3.

Bacterial Outer Membrane Proteins↗

PubMed2005

The respiratory pathogen Moraxella catarrhalis adheres to epithelial cells by interacting with fibronectin through ubiquitous surface proteins A1 and A2.

Moraxella catarrhalis ubiquitous surface protein (Usp) A1 has been reported to bind fibronectin and is involved in adherence. In this study, using M. catarrhalis mutants derived from clinical isolates, we show that both UspA1 and UspA2 bind fibronectin. Recombinant truncated UspA1/A2 proteins, together with smaller fragments spanning the entire molecule, were tested for binding to fibronectin. Both UspA1 and UspA2 bound fibronectin, and the fibronectin-binding domains were located within UspA1(299-452) and UspA2(165-318). These 2 truncated proteins inhibited binding of M. catarrhalis to Chang conjunctival epithelial cells to an extent similar to that by anti-human fibronectin antibodies. Our observations show that both UspA1 and UspA2 are involved in adherence to epithelial cells via cell-associated fibronectin. The biologically active sites within UspA1(299-452) and UspA2(165-318) have therefore been suggested to be potential candidates to be included in a future vaccine against M. catarrhalis.

Amino Acid Sequence↗

PubMed2005

Evaluation of western blot CagA seropositivity in Helicobacter pylori-seropositive and -seronegative subjects.

CagA seropositivity is an important risk factor for gastric adenocarcinoma and duodenal ulcer. However, CagA seropositivity is also found in Helicobacter pylori-seronegative subjects. Is CagA seropositivity in these subjects a sign of a past H. pylori infection, or does it represent a false-positive reaction? This study investigates the intensity of the CagA immune reaction and the variation in CagA seroprevalence with year of birth for 650 subjects belonging to the Malmo Preventive Medicine cohort. CagA and H. pylori seroprevalences were determined by Western blot analysis (Helicoblot 2.1) and enzyme-linked immunosorbent assay. The peak intensity of the CagA band was significantly lower in H. pylori-seronegative subjects than in those with concomitant H. pylori seropositivity. In H. pylori-seropositive subjects, peak CagA intensity had a bimodal distribution. The prevalence of CagA-seropositive but H. pylori-seronegative subjects increased successively and significantly with year of birth, in contrast to the prevalence of CagA-seropositive and H. pylori-seropositive subjects, which decreased significantly. However, within H. pylori-seropositive and -seronegative subgroups, CagA seroprevalences were constant for different birth cohorts. If CagA seropositivity in H. pylori-seronegative subjects represents a past H. pylori infection, there must have been some mechanisms of eradication that were more common in younger subjects and that were of more importance than the presence of gastric atrophy and the longer duration and higher prevalence of H. pylori infection found in older subjects. Antibiotic treatment of H. pylori was not common practice at the time of enrollment. On the other hand, a false-positive reaction would be constant and independent of birth cohorts, as with the H. pylori-seronegative subgroup of our study. Peak CagA intensity in H. pylori-seronegative subjects corresponded to the lower part of the bimodal distribution of peak CagA intensity in H. pylori-seropositive subjects. We conclude that a major proportion of CagA seropositivity in H. pylori-seronegative subjects represents a false-positive reaction. Peak CagA intensity has a bimodal distribution in H. pylori-seropositive subjects. Low-intensity CagA seropositivity in H. pylori-seropositive subjects is indeterminate, representing both false-positive and true-positive reactions.

Adult↗

PubMed2004

The emerging pathogen Moraxella catarrhalis interacts with complement inhibitor C4b binding protein through ubiquitous surface proteins A1 and A2.

Moraxella catarrhalis ubiquitous surface protein A2 (UspA2) mediates resistance to the bactericidal activity of normal human serum. In this study, an interaction between the complement fluid phase regulator of the classical pathway, C4b binding protein (C4BP), and M. catarrhalis mutants lacking UspA1 and/or UspA2 was analyzed by flow cytometry and a RIA. Two clinical isolates of M. catarrhalis expressed UspA2 at a higher density than UspA1. The UspA1 mutants showed a decreased C4BP binding (37.6% reduction), whereas the UspA2-deficient Moraxella mutants displayed a strongly reduced (94.6%) C4BP binding compared with the wild type. In addition, experiments with recombinantly expressed UspA1(50-770) and UspA2(30-539) showed that C4BP (range, 1-1000 nM) bound to the two proteins in a dose-dependent manner. The equilibrium constants (K(D)) for the UspA1(50-770) and UspA2(30-539) interactions with a single subunit of C4BP were 13 microM and 1.1 microM, respectively. The main isoform of C4BP contains seven identical alpha-chains and one beta-chain linked together with disulfide bridges, and the alpha-chains contain eight complement control protein (CCP) modules. The UspA1 and A2 bound to the alpha-chain of C4BP, and experiments with C4BP lacking CCP2, CCP5, or CCP7 showed that these three CCPs were important for the Usp binding. Importantly, C4BP bound to the surface of M. catarrhalis retained its cofactor activity as determined by analysis of C4b degradation. Taken together, M. catarrhalis interferes with the classical complement activation pathway by binding C4BP to UspA1 and UspA2.

Amino Acid Motifs↗

PubMed2004

Immunization with the truncated adhesin moraxella catarrhalis immunoglobulin D-binding protein (MID764-913) is protective against M. catarrhalis in a mouse model of pulmonary clearance.

Most Moraxella catarrhalis isolates express the outer membrane protein MID. In addition to its specific affinity for immunoglobulin D, MID functions as an adhesin and binds to human epithelium. The adhesive part is localized within MID(764-913). Two mid-deficient M. catarrhalis isolates were constructed and examined in a mouse model of pulmonary clearance. M. catarrhalis devoid of MID was cleared more efficiently, compared with the wild-type counterparts. Furthermore, mice immunized with MID(764-913) cleared M. catarrhalis much more efficiently, compared with mice immunized with bovine serum albumin. MID(764-913) is suggested as a promising candidate in a future M. catarrhalis vaccine.

Adhesins, Bacterial↗

PubMed2004

Detection of Mycobacterium tuberculosis complex in formalin-fixed, paraffin-embedded tissue specimens with necrotizing granulomatous inflammation by strand displacement amplification.

Rapid, reliable diagnosis of tuberculosis is essential to initiate correct treatment, avoid severe complications, and prevent transmission. Conventional microbiological methods may not be an option if samples are formalin-fixed and paraffin-embedded (FFPE) for histopathological examination. With the demonstration of necrotizing granulomatous inflammation, tuberculosis becomes an important differential diagnosis, although it was not initially suspected. Following paraffin extraction, BDProbeTec ET strand displacement amplification for detection of Mycobacterium tuberculosis complex (MTC) was applied to 47 prospectively and 19 retrospectively collected FFPE samples from various sources with granulomatous inflammation and results were compared to tuberculosis notification. Of the prospective samples, 20 were from patients who were notified as having tuberculosis and the assay was positive in 18 (90%). Specificity was 100%. For 27 of the patients with prospectively collected FFPE specimens, culture was performed on a specimen collected at a later date from the same location. Culture revealed MTC in 14 and nontuberculous mycobacteria in four. BDProbeTec ET was positive in 13 (92.8%) of the patients with positive MTC culture and negative in the remaining. The sensitivity and specificity in 19 archival samples was 40% and 100%, respectively, compared to notification data. The assay provided rapid, correct diagnosis on different sources of FFPE samples collected prospectively and therefore offers an important supplementary method for patients where tuberculosis was not initially suspected.

Fixatives↗

PubMed2003

Increased sensitivity of Mycobacterium tuberculosis Cobas Amplicor PCR following brief incubation of tissue samples on Löwenstein-Jensen substrate.

The sensitivity of Mycobacterium tuberculosis Cobas Amplicor PCR (MTB-PCR) is considerably lower for tissue than for airway samples, depending on both lower bacterial content and presence of inhibitory substances in tissues. The aim of this study was to improve the sensitivity of MTB-PCR in inhibiting biopsy samples. A brief-culture method was applied to 33 inhibitory tissue samples out of 356 obtained in Laboratory I, and compared with 44/197 such samples treated by dilution in Laboratory II. We found that 2-3 days' incubation on Löwenstein-Jensen substrate (LJ) significantly increased the sensitivity of MTB-PCR in samples exerting PCR inhibition. Sensitivity was 63% before and 92% following brief-culture of inhibitory tissue samples in Lab I, compared to 46% and 50%, respectively, with dilution in Lab II. Thus, dilution did not significantly increase sensitivity in inhibiting samples. Specificities were 99.4/99.4 and 99.2/98.2, respectively. The higher sensitivity attained by the LJ-method was probably due to diffusion of inhibiting substances into the substrate, as well as to increase in numbers of bacteria after the brief-culture. This method adds substantially to the value of MTB-PCR of biopsy material.

Biopsy↗

PubMed2003

The immunoglobulin D-binding protein MID from Moraxella catarrhalis is also an adhesin.

The Moraxella catarrhalis immunoglobulin D (IgD)-binding protein (MID) is a 200-kDa outer membrane protein displaying a unique and specific affinity for human IgD. MID is found in the majority of M. catarrhalis strains. In the present paper, we show that MID-expressing M. catarrhalis strains agglutinate human erythrocytes and bind to type II alveolar epithelial cells. In contrast, M. catarrhalis isolates with low MID expression levels and two mutants deficient in MID, but with readily detectable UspA1 expression, do not agglutinate erythrocytes and have a 50% lower adhesive capacity. To examine the adhesive part of MID, the protein was dissected into nine fragments covering the entire molecule. The truncated MID proteins were expressed in Escherichia coli, purified, and used for raising polyclonal antibodies in rabbits. Interestingly, by using recombinant fragments, we show that the hemagglutinating and adhesive part of MID is localized within the 150-amino-acid fragment MID(764-913). In addition, antibodies against full-length MID, MID(764-913), or a 30-amino-acid consensus sequence (MID(775-804)) inhibited adhesion to alveolar epithelial cells. Antibodies against UspA1, an outer membrane protein expressed in essentially all M. catarrhalis strains, also inhibited adhesion, suggesting that both MID and UspA1 are needed for optimal attachment to epithelial cells. Taken together, in addition to MID-dependent IgD binding, we have demonstrated that the outer membrane protein MID is a novel adhesin that would be a suitable target for a future vaccine against M. catarrhalis.

Adhesins, Bacterial↗

PubMed2003

The Moraxella catarrhalis immunoglobulin D-binding protein MID has conserved sequences and is regulated by a mechanism corresponding to phase variation.

The prevalence of the Moraxella catarrhalis immunoglobulin D (IgD)-binding outer membrane protein MID and its gene was determined in 91 clinical isolates and in 7 culture collection strains. Eighty-four percent of the clinical Moraxella strains expressed MID-dependent IgD binding. The mid gene was detected in all strains as revealed by homology of the signal peptide sequence and a conserved area in the 3' end of the gene. When MID proteins from five different strains were compared, an identity of 65.3 to 85.0% and a similarity of 71.2 to 89.1% were detected. Gene analyses showed several amino acid repeat motifs in the open reading frames, and MID could be called a putative autotransport protein. Interestingly, homopolymeric [polyguanine [poly(G)]] tracts were detected at the 5' ends within the open reading frames. By flow cytometry, using human IgD and fluorescein isothiocyanate-conjugated anti-IgD polyclonal antibodies, most strains showed two peaks: one high- and one low-intensity peak. All isolates expressing high levels of MID had 1, 2, or 3 triplets of G's in their poly(G) tracts, while strains not expressing MID had 4, 7, 8, or 10 G's in their poly(G) tracts or point mutations causing a putative preterminated translation. Northern blot analysis revealed that the mid gene was regulated at the transcriptional level. Experiments with nonclumping variants of M. catarrhalis proved that bacteria lost their MID expression by removing a G in their poly(G) tracts. Moraxella strains isolated from the nasopharynx or from blood and sputum specimens expressed MID at approximately the same frequency. In addition, no variation was observed between strains of different geographical origins (Australia, Europe, Japan, or the United States). MID and the mid gene were found solely in M. catarrhalis, whereas related Neisseria and Moraxella species did not express MID. Taken together, MID appears to be a conserved protein that can be found in essentially all M. catarrhalis strains. Furthermore, MID is governed by poly(G) tracts when bacteria undergo phase variation.

5' Flanking Region↗

PubMed2003

Several gene programs are induced in ciprofloxacin-treated human lymphocytes as revealed by microarray analysis.

Fluoroquinolones have immunomodulatory properties and interfere with cytokine production. The aim of this study was to characterize the extent of the superinduced mRNA levels in activated human lymphocytes incubated with ciprofloxacin (5 and 80 micro g/ml) using a cytokine gene expression microarray from R and D Systems (Abingdon, UK). Several gene transcripts (n=104) were up-regulated in cells treated with ciprofloxacin at 80 micro g/ml, whereas 98 transcripts were down-regulated out of 847 total genes included on the microarray. The increased mRNAs were distributed between major gene programs, including interleukins (36.5%), signal-transduction molecules (13.5%), adhesion molecules (10.6%), tumor necrosis factor and transforming growth factor-beta superfamilies (10.6%), cell-cycle regulators (9.6%), and apoptosis-related molecules (8.7%). To determine the specificity of the microarray, a quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), which contained a panel of 12 different cytokine mRNAs, was used. Eleven out of the 12 gene transcripts were up-regulated in the specific RT-PCR, whereas only eight were found to be increased in the microarray. A microarray from Clontech (Hampshire, UK), containing 588 different genes, was also included. Results obtained with this broad-coverage expression array slightly differed compared with the other microarray. We conclude that the fluoroquinolone ciprofloxacin at high concentrations interferes with several gene programs, which is in accordance with a mammalian stress response. From a technical point of view, a discrepancy may exist between data obtained by different microarrays and more specific methods such as quantitative RT-PCR.

Anti-Infective Agents↗

PubMed2002

The immunoglobulin D-binding part of the outer membrane protein MID from Moraxella catarrhalis comprises 238 amino acids and a tetrameric structure.

Moraxella catarrhalis IgD-binding protein (MID), a 200-kDa outer membrane protein comprising 2,139 amino acids, has recently been isolated and shown to display a unique and specific affinity for human IgD. To identify the IgD-binding region, MID was digested with proteases. In addition, a series of truncated fragments of MID were manufactured and expressed in Escherichia coli followed by analysis for IgD binding in Western and dot blots. The smallest fragment with essentially preserved IgD binding was comprised of 238 amino acid residues (MID(962-1200)). Shorter recombinant proteins gradually lost IgD-binding capacity, and the shortest IgD-binding fragment comprising 157 amino acids (MID(985-1142)) displayed a 1,000-fold reduced IgD binding compared with the full-length molecule. The truncated MID(962-1200) was efficiently attracted to a standard IgD serum and to purified myeloma IgD(kappa) and IgD(lambda) sera but not to IgG, IgM, or IgA myeloma sera. Furthermore, the fragment specifically bound to peripheral blood B lymphocytes, and the binding was inhibited by preincubation with anti-IgD-Fab polyclonal antibodies. Results obtained by introducing five amino acids randomly into MID(962-1200) using transposons suggested that alpha-helix structures were important for IgD binding. Ultracentrifugation experiments and gel electrophoresis revealed that native MID(962-1200) was a tetramer. Interestingly, tetrameric MID(962-1200) attracted IgD more than 20-fold more efficiently than the monomeric form. Thus, a tetrameric structure of MID(962-1200) is crucial for optimal IgD-binding capacity.

Adhesins, Bacterial↗