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Kaw Yan Chua - One of the best experts on this subject based on the ideXlab platform.

  • Mite amylase from Blomia tropicalis (Blo t 4): differential allergenicity linked to geographical regions.
    International archives of allergy and immunology, 2008
    Co-Authors: Nge Cheong, John Donnie A. Ramos, Bee Wah Lee, Chwee Ying Tang, Hiok Hee Chng, Rong Yao, Zongan Liang, Kaw Yan Chua
    Abstract:

    Background: Blomia tropicalis is an important domestic dust mite in the tropics and subtropics. This study describes cDNA cloning of the group 4 allergen of

  • Roles of Structure and Structural Dynamics in the Antibody Recognition of the Allergen Proteins: An NMR Study on Blomia tropicalis Major Allergen
    Structure (London England : 1993), 2008
    Co-Authors: Mandar T. Naik, Kaw Yan Chua, I-chun Kuo, Chi-fon Chang, Camy C.h. Kung, Tai-huang Huang
    Abstract:

    Summary Blo t 5 is the major allergen from Blomia tropicalis mites and shows strong IgE reactivity with up to 90% of asthmatic and rhinitis patients' sera. The NMR solution structure of Blo t 5 comprises three long α helices, forming a coiled-coil, triple-helical bundle with a left-handed twist. TROSY-NMR experiments were used to study Blo t 5 interaction with the Fab′ of a specific monoclonal antibody, mAb 4A7. The mAb epitope comprises two closely spaced surfaces, I and II, connected by a sharp turn and bearing critical residues Asn46 and Lys47 on one surface, and Lys54 and Arg57 on the other. This discontinuous epitope overlaps with the human IgE epitope(s) of Blo t 5. Epitope surface II is further predicted to undergo conformational exchange in the millisecond to microsecond range. The results presented are critical for the design of a hypoallergenic Blo t 5 for efficacious immunotherapy of allergic diseases.

  • The Blomia tropicalis allergens.
    Protein and peptide letters, 2007
    Co-Authors: Kaw Yan Chua, Nge Cheong, I-chun Kuo, Bee Wah Lee, Chiung-hui Huang, Lip Nyin Liew
    Abstract:

    Blomia tropicalis allergens are the most important mite allergens in tropical regions. Most of them only have 30-40% sequence identity with their Dermatophagoides counterparts and they share low IgE cross reactivity and exhibit different immunobiology. Unlike the pyroglyphid counterparts, Blo t 5 is the major allergen whereas Blo t 1 only has modest allergenicity.

  • Complete 1H, 13C and 15N resonance assignments of Blo t 5, a major mite allergen from Blomia tropicalis
    Journal of biomolecular NMR, 2007
    Co-Authors: Mandar T. Naik, Kaw Yan Chua, I-chun Kuo, Chi-fon Chang, Pei-ju Fang, Tai-huang Huang
    Abstract:

    House dust mites are main source of indoor allergens triggering the development of allergic diseases such as atopic dermatitis, perennial rhinitis and asthma. Blomia tropicalis (Family: Echimyopodidae) is a predominant and clinically important mite species in tropical and subtropical countries. B. tropicalis allergens are shown to be distinct and have relatively low to moderate IgE cross-reactivity with Dermatophagoides pteronyssinus mite allergens. Group 5 allergen, Blo t 5 is the major allergen from this mite and shows up to 90% IgE reactivity with asthmatic sera (Kuo et al. 2003). 13 C and/or 15 N isotopically enriched Blo t 5 samples were prepared as described previously (Arruda et al. 1997). Practically complete backbone (99.4%) and side-chain (95%) assignments were achieved by standard triple resonance experiments using Bruker Avance spectrometers equipped with cryoprobe. The chemical shifts are deposited in the BioMagResBank with accession number 7276. Chemical shifts index analysis of the data predicts Blo t 5 as an all-helical protein comprising of three long a-helices.

  • Molecular Cloning of Blomia tropicalis Allergens - A Major Source of Dust Mite Allergens in the Tropics and Subtropics
    Inflammation & allergy drug targets, 2006
    Co-Authors: Lynette Pei-chi Shek, Nge Cheong, Kaw Yan Chua, Bee Wah Lee
    Abstract:

    Allergic asthma, rhinitis, rhinoconjunctivitis and atopic dermatitis are the most common allergic disorders that are caused by the house dust mite (HDM). Beside pyroglyphid mites, the clinical importance of non-pyroglyphid mites has also been increasingly recognized in the recent years. Blomia tropicalis is the most important and ubiquitous mite species in tropical and subtropical regions of the world. Well-standardized and characterized allergens are essential for the diagnosis and therapy of house dust mite allergy as well as for the study of the pathophysiology of allergic disease. With the introduction of molecular biology, a number of house dust mite allergens were obtained by cloning the genes encoding the allergens. To date, seven allergens from Blomia tropicalis have been identified and characterized. Among these, Blo t 5, with unknown function, is the major allergen of Blomia tropicalis, with up to 92% of allergic patients sensitized to it. Native Blo t 5 has been purified and shown to consist of multiple isoforms. With advancing knowledge of these specific allergens, it is anticipated that targeted, effective, diagnostic, efficacious and safe therapeutic modalities would be developed.

Nge Cheong - One of the best experts on this subject based on the ideXlab platform.

  • Mite amylase from Blomia tropicalis (Blo t 4): differential allergenicity linked to geographical regions.
    International archives of allergy and immunology, 2008
    Co-Authors: Nge Cheong, John Donnie A. Ramos, Bee Wah Lee, Chwee Ying Tang, Hiok Hee Chng, Rong Yao, Zongan Liang, Kaw Yan Chua
    Abstract:

    Background: Blomia tropicalis is an important domestic dust mite in the tropics and subtropics. This study describes cDNA cloning of the group 4 allergen of

  • The Blomia tropicalis allergens.
    Protein and peptide letters, 2007
    Co-Authors: Kaw Yan Chua, Nge Cheong, I-chun Kuo, Bee Wah Lee, Chiung-hui Huang, Lip Nyin Liew
    Abstract:

    Blomia tropicalis allergens are the most important mite allergens in tropical regions. Most of them only have 30-40% sequence identity with their Dermatophagoides counterparts and they share low IgE cross reactivity and exhibit different immunobiology. Unlike the pyroglyphid counterparts, Blo t 5 is the major allergen whereas Blo t 1 only has modest allergenicity.

  • Molecular Cloning of Blomia tropicalis Allergens - A Major Source of Dust Mite Allergens in the Tropics and Subtropics
    Inflammation & allergy drug targets, 2006
    Co-Authors: Lynette Pei-chi Shek, Nge Cheong, Kaw Yan Chua, Bee Wah Lee
    Abstract:

    Allergic asthma, rhinitis, rhinoconjunctivitis and atopic dermatitis are the most common allergic disorders that are caused by the house dust mite (HDM). Beside pyroglyphid mites, the clinical importance of non-pyroglyphid mites has also been increasingly recognized in the recent years. Blomia tropicalis is the most important and ubiquitous mite species in tropical and subtropical regions of the world. Well-standardized and characterized allergens are essential for the diagnosis and therapy of house dust mite allergy as well as for the study of the pathophysiology of allergic disease. With the introduction of molecular biology, a number of house dust mite allergens were obtained by cloning the genes encoding the allergens. To date, seven allergens from Blomia tropicalis have been identified and characterized. Among these, Blo t 5, with unknown function, is the major allergen of Blomia tropicalis, with up to 92% of allergic patients sensitized to it. Native Blo t 5 has been purified and shown to consist of multiple isoforms. With advancing knowledge of these specific allergens, it is anticipated that targeted, effective, diagnostic, efficacious and safe therapeutic modalities would be developed.

  • Expression of the Blomia tropicalis paramyosin Blo t 11 and its immunodominant peptide in insect cells
    Biotechnology and Applied Biochemistry, 2006
    Co-Authors: John Donnie A. Ramos, Nge Cheong, Kaw Yan Chua
    Abstract:

    Blo t 11, a dust-mite (Blomia tropicalis) paramyosin, is an allergen with significant IgE reactivity that has potential as a diagnostic/therapeutic reagent for house-dust-mite allergy. The present study describes the successful expression of Blo t 11 and its immunodominant peptide fD in insect cells using a baculovirus expression system. The Blo t 11 and fD genes were cloned into the pMelBacA vector and the resulting vectors were co-transfected into Sf9 insect cells with Bac-N-Blue DNA. Plaque assay was used to select for recombinant virus that was then used to infect High Five insect cells for protein expression. Secreted proteins were harvested by immuno-affinity purification using monoclonal antibodies to Blo t 11. Purified proteins were analysed by immunoblotting, N-terminal sequencing and ELISA. Immunoblot analyses revealed the full-length Blo t 11 cDNA expressed as a minor protein band of approx. 200 kDa and two major protein bands of approx. 60 and 70 kDa. Clones expressing fD cDNA fragment produced a protein of approx. 30 kDa that was confirmed to be fD by N-terminal sequencing. Approx. 4–7.5 mg/l of fD and 1 mg/l of Blo t 11 were obtained by affinity purification. ELISA results showed that human IgE reactivity to these recombinant allergens was lower as compared with that of the native Blo t 11, suggesting that these baculovirus-expressed allergens exhibiting reduced allergenicity could be useful for the development of immunotherapeutic reagents for mite allergy.

  • Immunoglobulin E reactivity of native Blo t 5, a major allergen of Blomia tropicalis.
    Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology, 2004
    Co-Authors: Kaw Yan Chua, Nge Cheong, Lynette Pei-chi Shek, Bee Wah Lee
    Abstract:

    Summary Background Blo t 5 is a major allergen of Blomia tropicalis and its complementary DNA (cDNA) has been expressed in both prokaryotic and eukaryotic expression systems. Although the recombinant Blo t 5 has been well characterized, relatively less is known about its native counterparts and the allergenicity comparison of the native and recombinant Blo t 5 allergens has not been reported. Objective The aims of this study are to characterize the native counterpart of Blo t 5, and compare the allergenicity of native and recombinant Blo t 5 by in vivo and in vitro assays. Methods Native Blo t 5 were purified by immuno-affinity chromatography and characterized by proteomic means. The allergenicity of the allergen was evaluated by skin prick tests, human IgE ELISA, ELISA inhibition and histamine release assays. Results Native Blo t 5 consists of at least five distinct isoforms, ranging from pI 3 to 5.5. Allergenicity assessment of recombinant and native Blo t 5 based on skin reaction, IgE-binding capacity and histamine release in allergic individuals indicated that there was a good correlation between both forms of Blo t 5 in general. However, data from IgE ELISA inhibition assay revealed the presence of additional unique IgE epitopes in native Blo t 5. Conclusions At least five distinct isoforms of Blo t 5 have been identified. Comparative assessment of native and recombinant Blo t 5 revealed that the allergenicity of these two forms was similar but not completely identical suggesting that the various isoforms of native Blo t 5 may exhibit additional unique IgE epitopes.

Luis Caraballo - One of the best experts on this subject based on the ideXlab platform.

  • Hygienic conditions influence sensitization to Blomia tropicalis allergenic components: Results from the FRAAT birth cohort
    Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology, 2018
    Co-Authors: Josefina Zakzuk, Dilia Mercado, Adriana Bornacelly, Jorge Sánchez, Velky Ahumada, Nathalie Acevedo, Luis Caraballo
    Abstract:

    BACKGROUND In tropical zones, perennial exposure to house dust mite (HDM) allergens and helminth infections is present. Studying the impact of these conditions on the inception and evolution of allergic diseases is necessary to have an accurate view of their natural history. We aimed to evaluate the dynamics of genuine sensitization to Blomia tropicalis and Ascaris in children from the FRAAT birth cohort and the effects of helminth infection, environmental HDM allergen levels, and sociodemographic factors. METHODS Children were followed up to 6 years old. Specific IgE to recombinant allergens from B. tropicalis (Blo t 5 and Blo t 12) and Ascaris spp (Asc l 3, Asc l 13 and Asc s 1) was measured by ELISA at different time points. Allergen levels were measured in dust when children were 6 months old. RESULTS IgE sensitization increased over time up to 3 years old. Correlation among the specific IgE levels to B. tropicalis and Ascaris components is poor at year 1, but coefficients are high and significant (Spearman's rho coefficients >0.70) at year 6. Unhygienic conditions increased the odds of sensitization to B. tropicalis allergenic components. Blo t 5 levels were lower in the poorest. IgE response to Blo t 5 and Blo t 12 was less intense in children with high exposure to Blo t 5 (levels >80th percentile). CONCLUSION In this tropical community, the pattern of childhood IgE sensitization is different from that in developing countries and is influenced by the hygienic conditions.

  • Allergenic composition of the mite Suidasia medanensis and cross-reactivity with Blomia tropicalis.
    Allergy, 2005
    Co-Authors: Leonardo Puerta, Dilia Mercado, A. Lagares, E. Fernandez-caldas, Luis Caraballo
    Abstract:

    Background:  Mites of the genus Suidasia are commonly found in house dust and may play an allergenic role in exposed populations. However, the allergenic potential and clinical impact of this genus has not been well established. The main objective of this project was to evaluate the allergenic role of the mite Suidasia medanensis. Methods:  An extract of S. medanensis was prepared and the allergen composition determined by immunoblot. Specific IgE antibody levels to S. medanensis and Blomia tropicalis were evaluated by radioallergosorbent (RAST) in the sera of 97 allergic asthmatic patients and 50 nonallergic subjects. Cross-reactivity between S. medanensis and the mite species B. tropicalis and Dermatophagoides farinae was investigated by RAST and immunoblot inhibitions. Results:  Seventy-one asthmatic patients sera (73.2%) had positive IgE reactivity to S. medanensis; 14 allergens with molecular weights ranging from 7.5 to 105 kDa were detected. The most frequently detected had molecular weights of 30–31 (54.8%), 24.5 (42%), 21 (38.7%), 47 (35%) and 58 kDa (35.5%). Blomia tropicalis extract inhibited IgE binding to nine of these identified allergens. Four B. tropicalis allergens were inhibited by S. medanensis extract. RAST inhibition results demonstrated a high degree of inhibition by B. tropicalis (87.2%) and D. farinae (90.9%) than by S. medanensis (32%). Conclusions:  Sensitization to S. medanensis is common in asthmatic allergy patients in Cartagena. An important degree of cross-reactivity was established between S. medanensis and B. tropicalis, and D. farinae.

  • Importance of including Blomia tropicalis in the routine diagnosis of Venezuelan patients with persistent allergic symptoms.
    Allergy, 2004
    Co-Authors: F. A. Puccio, Luis Caraballo, Neil R. Lynch, O. Noga, A. Noda, I. Hagel, Elena López, R. I. Lopez, D. Mercado, M.c. Diprisco
    Abstract:

    Background: Blomia tropicalis is a common mite found in the house dust of many tropical countries including Venezuela. The prevalence of skin test and specific serum immunoglobulin (Ig)E reactivity to B. tropicalis in Venezuela has not been previously evaluated. Methods: In the present study we evaluated the skin reactivity by skin prick test and specific IgE by a multiple antigen blot assay, against B. tropicalis and Dermatophagoides pteronyssinus, in a group of 115 subjects who attended the Allergy Clinic of the Institute of Biomedicine, Caracas, Venezuela, and we studied possible cross reactions between similar proteins of these two mites. Results: One hundred and six patients with persistent allergic respiratory symptoms showed a positive skin prick test to at least one of the mite extracts, with the frequency of positive reactions to B. tropicalis being as high as to D. pteronyssinus. Twelve patients reacted only to D. pteronyssinus and 13 different patients only to B. tropicalis. Specific IgE to each of the mite extracts was found with similar frequency, and the results coincided with the skin test reactivity. Conclusions: The study indicated the importance of including B. tropicalis in routine diagnostic testing in tropical and sub-tropical situations.

  • Monoclonal Antibodies against Blo t 13, a Recombinant Allergen from Blomia tropicalis
    International Archives of Allergy and Immunology, 2002
    Co-Authors: Mayrel Labrada, Keiko Uyema, Minerva Sewer, Maritza González, Alexis Labrada, Luis Caraballo, Leonardo Puerta
    Abstract:

    Background: The recombinant allergen of Blomia tropicalis , rBlo t 13, shows 11% of IgE reactivity to sera from allergic patients. This allergen belongs to the fat

  • Structural and ligand binding analysis of recombinant blo t 13 allergen from Blomia tropicalis mite, a fatty acid binding protein.
    International archives of allergy and immunology, 1999
    Co-Authors: Leonardo Puerta, Silvia Jiménez, Malcolm W. Kennedy, Luis Caraballo
    Abstract:

    Background: We have previously described a cDNA (clone Bt6) encoding a novel allergen from Blomia tropicalis, which showed sequence similarities to the FABP/P2/cellular retinoic aci

Fook Tim Chew - One of the best experts on this subject based on the ideXlab platform.

  • Blo t 2: Group 2 allergen from the dust mite Blomia tropicalis
    Scientific reports, 2019
    Co-Authors: Kavita Reginald, Sze Lei Pang, Fook Tim Chew
    Abstract:

    Blomia tropicalis has been recognized as a cause of allergic diseases in the tropical and subtropical regions. Here we report the immuno-characterization of its group 2 allergen, Blo t 2. Allergen Blo t 2 was amplified from the cDNA of B. tropicalis using degenerate primers, expressed in Escherichia coli as a recombinant protein and purified to homogeneity. The mature protein of Blo t 2 was 126 amino acids long with 52% sequence identity to Der p 2 and apparent molecular mass of 15 kDa. Circular dichroism spectroscopy showed that Blo t 2 is mainly a beta-sheeted protein. We confirmed the presence of three disulfide bonds in recombinant (r) Blo t 2 protein using electrospray mass spectrometry. Thirty-four percent of dust-mite allergic individuals from the Singapore showed specific IgE binding to rBlo t 2 as tested using immuno dot-blots. IgE-cross reactivity assays showed that Blo t 2 had between 20–50% of unique IgE-epitopes compared to Der p 2. IgE binding of native and recombinant forms of Blo t 2 were highly concordant (r2 = 0.77, p 

  • blo t 2 group 2 allergen from the dust mite Blomia tropicalis
    Scientific Reports, 2019
    Co-Authors: Sze Lei Pang, Kavita Reginald, Fook Tim Chew
    Abstract:

    Blomia tropicalis has been recognized as a cause of allergic diseases in the tropical and subtropical regions. Here we report the immuno-characterization of its group 2 allergen, Blo t 2. Allergen Blo t 2 was amplified from the cDNA of B. tropicalis using degenerate primers, expressed in Escherichia coli as a recombinant protein and purified to homogeneity. The mature protein of Blo t 2 was 126 amino acids long with 52% sequence identity to Der p 2 and apparent molecular mass of 15 kDa. Circular dichroism spectroscopy showed that Blo t 2 is mainly a beta-sheeted protein. We confirmed the presence of three disulfide bonds in recombinant (r) Blo t 2 protein using electrospray mass spectrometry. Thirty-four percent of dust-mite allergic individuals from the Singapore showed specific IgE binding to rBlo t 2 as tested using immuno dot-blots. IgE-cross reactivity assays showed that Blo t 2 had between 20–50% of unique IgE-epitopes compared to Der p 2. IgE binding of native and recombinant forms of Blo t 2 were highly concordant (r2 = 0.77, p < 0.0001) to rBlo t 2. Dose-dependent in vitro histamine was observed when rBlo t 2 was incubated with whole blood of Blo t 2 sensitized individuals, demonstrating that it is a functional allergen. Nine naturally occurring isoforms of Blo t 2 were identified in this study, each having between 1–3 amino acid variations compared to the reference clone. Blo t 2 is a clinically relevant allergen of B. tropicalis as it has unique IgE epitopes compared to major group 2 allergens from Dermatophagoides spp.

  • NMR structure and IgE epitopes of Blo t 21, a major dust mite allergen from Blomia tropicalis
    The Journal of biological chemistry, 2012
    Co-Authors: Kang Wei Tan, Fook Tim Chew, Yunfeng Gao, Tan Ching Ong, Yuen Sung Tiong, Kang Ning Wong, Yu-keung Mok
    Abstract:

    Blo t 21 is a paralogue of the group 5 allergen, Blo t 5, a major allergen from the dust mite Blomia tropicalis. Blo t 21 has moderate sequence identity (40.7%) to Blo t 5 and low to moderate cross-reactivity to Blo t 5. In B. tropicalis, the most prevalent and allergenic allergens are in the order of Blo t 21, Blo t 5, and Blo t 7. Here, we determined the NMR solution structure of Blo t 21, which represents the first structure of the group 21 dust mite allergen. The structure of Blo t 21 closely resembles the structures of Blo t 5 and Der p 5, comprising three anti-parallel α-helices arranged in a helical bundle. Using site-directed mutagenesis and specific IgE binding ELISA, Blo t 21 was found to contain both conserved and unique charged IgE epitope residues at the L2 loop region and on helix α3. Cross-inhibition assays confirmed that Blo t 21 has a low to moderate cross-reactivity with Blo t 5 and Der p 5 and represents a novel group of major allergen in B. tropicalis. In addition to group 5 allergens, Blo t 21 has also a low to moderate cross-reactivity with group 21 allergens from Dermatophagoides mites, confirming that B. tropicalis is a major and distinct source of dust mite allergens.

  • Identification and characterization of a novel allergen from Blomia tropicalis: Blo t 21
    The Journal of allergy and clinical immunology, 2007
    Co-Authors: Yunfeng Gao, De Yun Wang, Tan Ching Ong, S. L. Tay, Kwong Hsia Yap, Fook Tim Chew
    Abstract:

    Background Allergenic components from Blomia tropicalis are important triggers of allergies in the tropics. Objective We sought to identify and characterize a novel allergen, Blo t 21, from B tropicalis . Methods Blo t 21 was initially identified from an expressed sequence tag database generated from a B tropicalis cDNA library. Allergenicity of this antigen was examined by means of skin prick testing, ELISA, and IgE immuno-dot blotting. We evaluated whether Blo t 21 and Blo t 5 were cross-reactive by using IgE inhibition ELISAs. Results Blo t 21, a 129-amino-acid protein sharing 39% identity with Blo t 5, is a product of a single-copy gene. It has an α-helical secondary structure and localizes to midgut and hindgut contents of B tropicalis , as well as fecal particles. Positive responses to Blo t 21 were shown in 93% (40/43) by means of ELISA and 95% (41/43) by means of skin prick testing when assayed in 43 adult patients with ongoing persistent allergic rhinitis. However, sera of 494 consecutive individuals attending outpatient allergy clinics over 1½ years showed 57.9% (286/494) had positive responses to Blo t 21. Although the majority (>75%) of sensitized individuals were cosensitized to both Blo t 5 and Blo t 21, these 2 allergens had a low-to-moderate degree of cross-reactivity. Conclusion Blo t 21 is a major allergen in B tropicalis that is not highly cross-reactive to Blo t 5, despite sharing some sequence and structural identity. Clinical implications Blo t 21, representing a new group of allergens, is an important B tropicalis allergen.

  • sensitization to Blomia tropicalis and dermatophagoides pteronyssinus a comparative study between singapore and taiwan
    Asian Pacific Journal of Allergy and Immunology, 1999
    Co-Authors: Fong Cheng Yi, Lynette Pei-chi Shek, Fook Tim Chew, N. Cheong, Kaw Yan Chua
    Abstract:

    : Blomia tropicalis (Bt) and Dermatophagoides pteronyssinus (Dp) are the predominant domestic mites species in Singapore and Taiwan. This study aims to characterize and compare the mite sensitization profiles in both countries. Skin prick tests were performed on 203 Singaporeans with Dp and Bt crude extracts. In vitro IgE and IgG4 reactivity to extracts and specific allergens (Der p 1, Der p 2 Der p 5 and Blo t 5) were determined by immunoassays. Approximately 91% of the tested Singaporeans were skin test positive for both Bt and Dp. Both populations share similar frequencies of in vitro IgE reactivity to all the allergens tested, but they differ in the pattern and magnitude of allergen sensitization. Although Der p 1, Der p 2 and Blo t5 are major sensitizing allergens in both countries, Blo t 5 is a more potent one in Singapore, probably reflecting the high level of exposure to Bt. The unique major Bt and Dp allergens should be included for precise diagnosis and effective immuno-therapeutic treatment of mite allergy in both countries.

Leonardo Puerta - One of the best experts on this subject based on the ideXlab platform.

  • Allergenic composition of the mite Suidasia medanensis and cross-reactivity with Blomia tropicalis.
    Allergy, 2005
    Co-Authors: Leonardo Puerta, Dilia Mercado, A. Lagares, E. Fernandez-caldas, Luis Caraballo
    Abstract:

    Background:  Mites of the genus Suidasia are commonly found in house dust and may play an allergenic role in exposed populations. However, the allergenic potential and clinical impact of this genus has not been well established. The main objective of this project was to evaluate the allergenic role of the mite Suidasia medanensis. Methods:  An extract of S. medanensis was prepared and the allergen composition determined by immunoblot. Specific IgE antibody levels to S. medanensis and Blomia tropicalis were evaluated by radioallergosorbent (RAST) in the sera of 97 allergic asthmatic patients and 50 nonallergic subjects. Cross-reactivity between S. medanensis and the mite species B. tropicalis and Dermatophagoides farinae was investigated by RAST and immunoblot inhibitions. Results:  Seventy-one asthmatic patients sera (73.2%) had positive IgE reactivity to S. medanensis; 14 allergens with molecular weights ranging from 7.5 to 105 kDa were detected. The most frequently detected had molecular weights of 30–31 (54.8%), 24.5 (42%), 21 (38.7%), 47 (35%) and 58 kDa (35.5%). Blomia tropicalis extract inhibited IgE binding to nine of these identified allergens. Four B. tropicalis allergens were inhibited by S. medanensis extract. RAST inhibition results demonstrated a high degree of inhibition by B. tropicalis (87.2%) and D. farinae (90.9%) than by S. medanensis (32%). Conclusions:  Sensitization to S. medanensis is common in asthmatic allergy patients in Cartagena. An important degree of cross-reactivity was established between S. medanensis and B. tropicalis, and D. farinae.

  • Monoclonal Antibodies against Blo t 13, a Recombinant Allergen from Blomia tropicalis
    International Archives of Allergy and Immunology, 2002
    Co-Authors: Mayrel Labrada, Keiko Uyema, Minerva Sewer, Maritza González, Alexis Labrada, Luis Caraballo, Leonardo Puerta
    Abstract:

    Background: The recombinant allergen of Blomia tropicalis , rBlo t 13, shows 11% of IgE reactivity to sera from allergic patients. This allergen belongs to the fat

  • Structural and ligand binding analysis of recombinant blo t 13 allergen from Blomia tropicalis mite, a fatty acid binding protein.
    International archives of allergy and immunology, 1999
    Co-Authors: Leonardo Puerta, Silvia Jiménez, Malcolm W. Kennedy, Luis Caraballo
    Abstract:

    Background: We have previously described a cDNA (clone Bt6) encoding a novel allergen from Blomia tropicalis, which showed sequence similarities to the FABP/P2/cellular retinoic aci

  • cloning and ige binding of a recombinant allergen from the mite Blomia tropicalis homologous with fatty acid binding proteins
    International Archives of Allergy and Immunology, 1997
    Co-Authors: Luis Caraballo, Asil Avjiouglu, Beatriz Martínez, Dilia Mercado, S. Jiménez, Leonardo Puerta, David G Marsh
    Abstract:

    To characterize the allergens of Blomia tropicalis, a cDNA library was constructed and screened with allergic sera from asthmatic patients. One clone, Bt6, was subcloned and sequenced. The nucleotide sequence of 934 bp length shows a 390-bp reading frame which encodes a 130-amino acid protein with a MW 14.8 kD. No potential glycosylation site was found in the predicted protein. The inferred amino acid sequence has no homology to known allergens. It has a cyto-solic fatty acid-binding protein (FABP) signature at 5–22 amino acid residues, 42.3% identity with the Sm14-FABP of Schistosoma mansoni and 36% identity with FABPs from rat, mouse, bovine and human. The protein was expressed as a GST fusion protein and the purified GST-Bt6 used for dot blot, RAST and RAST inhibition assays. The frequency of IgE binding of allergic sera to Bt6 was low (11%) and usually weak. One positive serum did, however, show strong reactivity by RAST and dot blot and Bt6 could inhibit 60% of the IgE binding of this serum to the B. tropicalis extract. These data show that Bt6 encodes a mite FABP with allergenic properties, which are pronounced in some atopic subjects.

  • Sequential determinations of Blomia tropicalis allergens in mattress and floor dust samples in a tropical city.
    The Journal of allergy and clinical immunology, 1996
    Co-Authors: Leonardo Puerta, Dilia Mercado, Enrique Fernández-caldas, Richard F. Lockey, Luis Caraballo
    Abstract:

    Abstract BACKGROUND: The mite species Blomia tropicalis is commonly found in tropical and subtropical regions, and it is an important source of allergen in the city of Cartagena, Columbia. AIM: The study was designed to determine seasonal allergen levels of B. tropicalis in homes of patients with asthma and mite allergy. METHODS: Dust samples from mattresses and floors in 20 homes were collected on a monthly basis for 1 year. Outdoor temperature, relative humidity, and rainfall were recorded. RAST inhibition was performed on extracts of dust samples. Allergen levels were compared with variations in climate. RESULTS: B. tropicalis allergens were detected in all mattress samples. More than 50% RAST inhibition was detected in 30% of mattress samples and in 4.3% of floor samples, reflecting a high concentration of allergen. Significant correlations were only found between allergen levels and absolute humidity. CONCLUSION: Levels of B. tropicalis allergen fluctuated minimally in Cartagena, Colombia. (J ALLERGY CLIN IMMUNOL 1996;97:689-91.)