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  • 1
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: A 98-kDa mite paramyosin (Der f 11) from Dermatophagoides farinae (Df) is highly allergenic, and its cDNA (Df642) has been cloned. This paper describes the sequence characteristics and the mapping of the immunodominant human IgE and IgG epitopes of Der f 11.
 Methods: The protein sequence analysis was performed with a combination of FASTA, GCG, and CLUSTAL W computing packages. The whole cDNA insert and its PCR-derived DNA fragments were generated and expressed in E. coli. These overlapping recombinant peptides (F1 to F5) were used for B-cell epitope mapping with 18 mite-allergic sera by dot immunoassays.
 Results: Df642 cDNA encodes a partial sequence that contains the 2nd to 26th 28-residue repeats and lacks the N-terminus and the C-terminus. The sequence identity of the Der f 11 with other known paramyosins is 34–60%. The dominant IgE epitopes are located in peptides F1 and F4, whereas the dominant IgG epitopes are located in peptides F1 and F2. These peptides are more reactive than whole rDf642.
 Conclusions: Mite paramyosin is very similar to other known paramyosins. The human IgE and IgG epitopes are scattered throughout the entire molecule. Data also indicate the presence of unique IgE and IgG epitopes in Der f 11.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 60 (2005), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Blomia tropicalis is an important mite species in the tropical and sub-tropical regions of the world. Blo t 5 is the major allergen with up to 70% sensitization rates in B. tropicalis allergic populations.Methods:  Mice were immunized intramuscularly with naked plasmid DNA encoding Blo t 5 gene with in vivo electroporation. Blo t 5 monoclonal antibodies were generated using methylcellulose-based hybridoma kit. Monoclonal antibody (mAb) 4A7 was characterized by two-dimensional electrophoresis immunoblotting. A specific quantitative two-site enzyme-linked immunosorbent assay (ELISA) was developed with mAb 4A7 and guinea pigs Blo t 5 polyclonal antibody as capture and detection antibodies, respectively. This system was tested with Blo t 5 in crude extracts and dust samples.Results:  A high-affinity mAb 4A7 recognizing several isoforms of Blo t 5 has been generated. Monoclonal antibody 4A7 is useful for immunoblotting and two-site ELISA. The two-site ELISA developed has a high sensitivity, with a detection limit of 10 pg/ml. The assay is species-specific and recognized the same epitopes on both native and recombinant Blo t 5. The assay developed is able to detect Blo t 5 in commercial diagnostic and therapeutic B. tropicalis extract. Blo t 5 quantification in dust samples showed that Blo t 5 is present in a high quantity in Singapore dust.Conclusions:  A highly sensitive and specific two-site ELISA has been developed. The assay system developed is useful for the quantification of Blo t 5 in mite and environmental dust extracts.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The complementary DNA (cDNA) encoding for Blo t 11, a 102 kD allergen from Blomia tropicalis (Bt) was isolated, expressed and characterized previously. This study aimed to isolate the native Blo t 11 allergen and compare its allergenicity with the recombinant forms.Methods: Native Blo t 11 (nBlo t 11) was isolated from crude Bt extract by immuno-affinity chromatography, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot, and verified by MALDI-TOF MS. Recombinant full-length Blo t 11 (rFL-Blo t 11) and its immunodominant peptide (fD) were expressed as glutathione S-transferase (GST)-fusion proteins in Escherichia coli. Immunoglobulin E (IgE) reactivity of the Blo t 11 allergens were determined by enzyme-linked immunosorbent assay (ELISA) and skin prick test. The inhibition capacity of the nBlo t 11 against fD and vice versa was determined by absorption studies.Results: Affinity purified nBlo t 11 was susceptible to degradation with the major degraded product resolved at ∼66 kD. The nBlo t 11 was confirmed by immunoblot analysis and MALDI-TOF MS that generated 13 peptides with complete identity to the deduced amino acid sequence of Blo t 11. Comparative in vitro and in vivo allergenicity tests and the cross inhibition studies between the native and recombinant Blo t 11 showed that recombinant fD, but not the rFL-Blo t 11, has comparable IgE reactivity with the native counterpart.Conclusions: This comparative study confirmed that the recombinant peptide fD contains the main immunodominant region of Blo t 11. This recombinant peptide, instead of the full-length protein, is a good candidate for diagnostic and therapeutics development for mite allergy.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Blo t 11 is a high molecular weight allergen from Blomia tropicalis with significant immunoglobulin (Ig)E binding frequency. Native and recombinant Blo t 11 are susceptible to degradation and the isolation and expression of the allergen is problematic thus obtaining sufficient amounts of purified Blo t 11 for antibody production is limiting. DNA-based immunization is an attractive alternative strategy that bypasses antigen purification for antibody production.Objectives:  To use a DNA-based immunization protocol for the production and characterization of Blo t 11 monoclonal antibodies (mAbs).Methods:  The 2625 bp cDNA coding for Blo t 11 was cloned into a mammalian expression vector and immunized intramuscularly with electroporation into mice. Monoclonal antibodies to Blo t 11 were generated using a methylcellulose-based hybridoma cloning kit. These mAbs were utilized for native Blo t 11 isolation and the development of sandwich enzyme-linked immunosorbent assay (ELISA).Results:  Six mAbs recognizing the native and recombinant Blo t 11 were generated and characterized. Native Blo t 11 was affinity purified from Bt extract and its identity was confirmed by matrix assisted laser desorption/ionization – time of flight mass spectrometry. The native Blo t 11 showed IgE reactivity with 67% of mite allergic sera. A two-site ELISA developed showed a detection limit of 100 pg/ml of Blo t 11.Conclusion:  A DNA-based immunization protocol was successfully used to generate Blo t 11 mAbs with a spectrum of distinct epitopes located throughout the whole molecule, and they are useful for immunoaffinity purification and immunoassays.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 58 (2003), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  The group 1 mite allergens are the most significant indoor allergens and they belong to the papain-like cysteine protease family. To date there is only one published report on the isolation and characterization of group 1 allergens from Blomia tropicalis mites. The aims of the study are to determine the cross-reactivity between group 1 allergens and to evaluate their clinical importance in allergic patients.Methods:  The full-length Blo t 1 gene was obtained by SMARTTM RACE cDNA amplification method using gene-specific primers. The sequence alignment was performed using LOOK followed by three-dimensional homology modeling. The cDNA was expressed in Pichia pastoris as a secretory protein. Identification of native Blo t 1 in crude mite and spent mite medium extracts was done by Western immunoblot using monoclonal antibody. Allergenicity of recombinant Blo t 1 and native Der p 1 was examined by human IgE ELISA with 80 asthmatic sera.Results:  The cDNA sequence consists of 1105 base pairs, including 5′- and3′-untranslating regions, encoding an open reading frame of 330 amino acid residues. The predicted molecular weight of the deduced protein was approximately 38 kDa. Blo t 1 shared 53 and 34% nucleotide and amino acid, respectively, sequence homology with Der p 1. Native Blo t 1 was detected in both crude mite and spent mite medium extracts, and its estimated molecular weight was about 26 kDa. The recombinant Blo t 1 reacted positively with IgE in 90 and 65% of sera from asthmatic children and adults, respectively, indicating that it is a major allergen. The correlation of human IgE reactivity between Blo t 1 and Der p 1 was low in these sera.Conclusion:  The full-length cDNA encoding group 1 Blomia tropicalis mite allergen (designated as Blo t 1) has been characterized and expressed from local mites in Singapore. This fecal allergen showed high frequency of human IgE reactivity with asthmatic sera in the tropics and there was a low correlation of IgE reactivity between Blo t 1 and Der p 1.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 25 (1995), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background The allergen Der p 7 from Dermatophagoides pteronyssinus has been defined by molecular cloning and shown to be an important specificity in 50% of miteallergic patients.Objective This study compares the cDNA sequence and serological reactivity of Der f 7 from D. farinae with Der p 7. Method cDNA encoding Der f 7 was amplified by polymerase chain reaction. sequenced and expressed as a fusion with glutathione-S-transferase for IgE and monoclonal antibody binding studies.Results Der f 7 cDNA encoded a 213 polypeptide containing a predicted 17 amino acid leader sequence, no cysteines and a single N-glycosylation site similar to Der p 7. The predicted 196 residue mature polypeptide had 86% identity lo Der p 7 and a calculated molecular weight of 22 34SDa. No homologues were found in searches of the data banks. The Der f 7 fusion protein showed a single band of 46 k Da by sodium dodccyl snlfute-polyaerylamide gel electrophoresis (SDS-PAGF) and reacted with IgE antibodies in 19/41 (46%) of sera from asthmatic children. The degree of binding was usually 30% of that to Der p 7 consistent with the exposure of the patients to D. Pteronyssinus. Monoclonal antibodies (WH9 and WH22) against Der p 7 reacted with Der f 7 but inhibition studies showed a 10-fold difference in reactivity.Conclusion Der f 7 has a predicted 213 residue polypeptide with 86% homology and serological cross reactivity to Der p 7.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Blo t 1 is a cysteine protease-like allergen from Blomia tropicalis. Recombinant Blo t 1 binds up to 90% of IgE from allergic patients and shows limited cross-reactivity to Der p 1. The generation of monoclonal antibodies (mAbs) against Blo t 1 is important for the detection, isolation and characterization of the native form of the allergen.Methods Mice were immunized intramuscularly with naked plasmid DNA encoding Blo t 1 gene with in vivo electroporation and boosted intraperitoneally with recombinant Blo t 1. mAbs against Blo t 1 were generated using a methylcellulose-based hybridoma cloning kit. The native Blo t 1 was isolated by mAb affinity purification and its allergenicity was determined by ELISA. A two-site ELISA for Blo t 1 was developed using the mAbs generated.Results A DNA-based immunization protocol induced high titre Blo t 1-specific antibodies in mice. Six stable hybridoma clones secreting mAbs recognizing the native and recombinant Blo t 1 were generated. The native Blo t 1 was affinity-purified from a B. tropicalis extract and its allergenicity was determined at 63% using a panel of Singaporean and Malaysian mite allergic patients' sera. A two-site ELISA was developed, which showed a detection limit of 10 ng/mL of Blot t 1.Conclusion Six Blo t 1 mAbs were successfully generated by DNA immunization. These mAbs are useful for nBlo t 1 immunoaffinity isolation and quantitative immunoassays for Blo t 1 in mite and environmental dust extracts.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 33 (2003), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background The identification of immunodominant peptides containing the IgE and IgG epitopes on allergen molecules is an important step in understanding the interaction of the allergen with the immune system and, thus, essential for the development of effective immunotherapeutic and diagnostic reagents. The present study aimed to map the IgE and IgG immunodominant peptides of Blomia tropicalis (Bt) allergen Blo t 11, a high molecular weight allergen homologous to paramyosin, exhibiting important allergenic activity.Methods Eleven overlapping fragments of Blo t 11 cDNA gene were expressed as glutathione s-transferase (GST) fusion peptides, which were affinity-purified using the glutathione-Sepharose column. Human IgE and IgG immunodominant peptides were determined by dot blot immunoassay using crude Bt extract-positive sera from asthmatic patients. Evaluation of allergenicity, specific hIgG subclass analysis, and cross- and self-inhibition studies were determined by enzyme-linked immunosorbent assay.Results Blo t 11 contains multiple IgE and IgG immunodominant peptides scattered throughout the molecule. The dominant IgE and IgG peptides were mapped at amino acid positions 336–557 and 698–875, respectively. An immunodominant peptide (fD) registered a higher percentage of IgE and IgG reactivity compared to the rFL-Blo t 11. Significant serum levels of Blo t 11- and fD-specific IgG1, IgG2 and IgG4, but not IgG3 were detected in the Bt extract-positive sera tested. Cross-inhibition study revealed the rFL-Blo t 11 was significantly inhibited by fD.Conclusion The IgE and IgG immunodominant peptides of Blo t 11 have been mapped. Our data suggest that utilization of Blo t 11 fragment(s) or chimeric fusion fragments containing IgE and IgG epitopes could be a better alternative in the development of diagnostic and therapeutic reagents for mite allergy.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Tropomyosin belongs to a class of highly conserved proteins in invertebrates and vertebrates. The invertebrate tropomyosins are allergenic in man with high IgE cross-reactivity and have been therefore referred to as pan-allergens.Objectives This study aimed to clone and identify the IgE epitopes of tropomyosin from Blomia tropicalis (Blo t 10) mite. Cross-reactivity between the IgE epitopes of Blo t 10 and Der p 10 was also evaluated.Methods Blo t 10 was isolated using mouse anti-Der p 10 antibodies. Allergenicity of the cloned Blo t 10 was confirmed by skin prick test (SPT) and enzyme-linked immunosorbent assay (ELISA). Dose-dependent inhibition assay was performed to determine the degree of IgE cross-reactivity between Blo t 10 and Der p 10. Overlapping polymerase chain reaction-derived cDNA were generated and expressed as glutathione-S-transferase (GST) recombinant proteins in Escherichia coli and used to identify shared and unique IgE epitopes of Blo t 10 and Der p 10.Results The cloned Blo t 10 shared up to 96% amino acid identity to tropomyosin of other mites. SPT and ELISA IgE-immunoassay showed recombinant Blo t 10 sensitization rates of between 20% and 29% in atopic subjects. Results of SPT and dose-dependent inhibition assays showed that some allergic individuals had unique IgE epitopes for Blo t 10. IgE epitope mapping of Blo t 10 revealed that the epitopes were mainly located at N- and C-termini of the molecule. The results of ELISA inhibition assays of overlapping recombinant fragments indicated that the unique IgE epitopes of Blo t 10 were located at the C-terminal.Conclusion Although Blo t 10 and Der p 10 are highly conserved (shared 95% amino acids identity) and significantly cross-reactive, unique IgE epitopes do exist. The results suggest the potential deficiency of using only one of these highly conserved allergens as diagnostic or therapeutic reagents.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 25 (1995), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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