Protein sequence analysis of a novel 103-kDa Dermatophagoides pteronyssinus mite allergen and prevalence of serum immunoglobulin E reactivity to rDer p 11 in allergic adult patients

BACKGROUND: House dust mites are regarded as important indoor allergens. While the most studies mite allergens are low molecular weight (mw), a high mw Dermatophagoides farinae mite paramyosin (Der f 11) has recently been cloned. We have also cloned a novel high mw Dermatophagoides pteronyssinus (Dp) mite allergen, Der p 11. OBJECTIVE: The aim of this study was to isolate and express a cDNA gene coding for a Der p 11 allergen, to compare the sequence of Der p 11 with other antigens and to evaluate the presence of IgE reactivity to the recombinant protein (rDer p 11) in the sera of allergic adult patients. METHODS: The full-length Der p 11 gene was isolated by cDNA library screening, 5'-3' rapid amplification of cDNA ends and PCR. The cDNA gene was expressed as a glutathione-S-transferase fusion protein in Escherichia coli. The allergenicity of rDer p 11 was tested by human IgE immunodot or immunoblot assay in a large panel of 100 allergic patients with bronchial asthma, allergic rhinitis or eczema. RESULTS: Der p 11 is a 2965 bp cDNA gene with a 2625 bp open reading frame coding for a 875 amino acid protein. The deduced amino acid sequence of the Der p 11 showed significant homology with various invertebrate paramyosins. The prevalence of serum IgE reactivity to rDer p 11 on immunodot assay ranged from 41.7% to 66.7% in different allergic patient groups, whereas it was rare in non-atopic patients with urticaria (18.8%) and in normal individuals (8%). A high frequency (five out of eight) of MAST(Dp)- allergic serum samples had specific IgE-binding activity to rDer p 11 or its fragments on immunoblot assay, even though their IgE-binding activity to Dp extract was either weak or negative. CONCLUSION: The 103-kDa Der p 11 appears to be major Dp mite allergen with a high frequency of IgE reactivity in sera of patients allergic to mites.     

Protein sequence analysis and mapping of IgE and IgG epitopes of an allergenic 98-kDa Dermatophagoides farinae paramyosin, Der f 11

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 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.     

Lymphocyte proliferative responses to the purified Dermatophagoides farinae major allergen in untreated and hyposensitized atopic patients

We investigated the proliferative response of lymphocytes from mite-sensitive patients (RAST D.far greater than 3.5 PRU/ml) in the presence of the major allergen Der.f.I purified from Dermatophagoides farinae. Comparative studies were carried out with peripheral blood mononuclear cells from non-atopic donors (RAST = 0), and from patients undergoing hyposensitization treatment (5 to 24 months). According to Student's t-test, there was no significant difference in the Der.f.I-induced proliferation of peripheral blood mononuclear cells from normal donors, untreated atopic patients and hyposensitized patients. In conclusion, it was impossible to discriminate between normal donors, atopic patients and hyposensitized patients with regard to their circulating lymphocyte responses to the purified major allergen Der.f.I.     

粉尘螨变应原第10组分基因克隆表达及生物信息学分析

目的:克隆粉尘螨变应原第10组分(Der f 10)基因并建立其原核表达体系。方法:提取粉尘螨总RNA,反转录后经套式PCR扩增出目的基因并克隆至pMD19-T载体测序,将测序正确的目的基因插入表达质粒pET28a,转化E.coliBL21(DE3)用IPTG诱导表达,用SDS-PAGE和Western blot鉴定重组蛋白。结果:RT-PCR扩增获得Der f 10,琼脂糖凝胶电泳见一条约888 bp的条带,与参考序列(GenBank No.EU 106617)同源性高达99.8%。将pET28a(+)-Der f 10质粒转化宿主菌E.coli BL21,SDS-PAGE电泳时出现特异性条带,Western blot表明重组蛋白可与抗His-Tag Mab抗体结合。生物信息学软件预测获得的Der f 10重组体由295个氨基酸组成的疏水性蛋白,相对分子质量为34 233.1 Da,二级结构包括α-螺旋(91.86%)、延伸主链(1.36%)和无规卷曲(6.78%),含有5个原肌球蛋白模序分别位于84～101、120～140、145～173、175～198和231～256氨基酸处。结论:获得了Der f 10编码基因,成功建立其原核表达体系,为生产重组变应原用于临床诊断与治疗奠定基础。     

粉尘螨Ⅰ类抗原cDNA的克隆表达和初步鉴定

目的　构建粉尘螨Ⅰ类抗原 (Derf1)cDNA基因的重组表达质粒 ,并于E .coli表达。方法　用BamHⅠ和SacⅠ从重组质粒pMD 18T Derf 1上切下Derf1基因 ,插入表达载体pET32a( )质粒 ,转化大肠杆菌BL2 1,在氨苄青霉素阳性的LB平板上筛选阳性重组子 ,并经双酶切及PCR扩增鉴定。重组质粒pET32a( ) Derf 1转化大肠杆菌 ,IPTG诱导表达后进行SDS PAGE电泳和薄层凝胶扫描定量分析。结果　对重组质粒进行酶切和PCR鉴定 ,与预期结果相符 ,证明已成功构建携带Derf1基因的重组原核表达质粒pET32a( ) Derf 1。核酸序列测定及同源性分析证实所构建的原核表达质粒pET32a( ) Derf1中所含的Derf1基因与GenBank中的Derf1序列同源性达到 99.5 %。Derf 1基因在大肠杆菌诱导表达后获得Mr 约4 5 0 0 0的蛋白 ,蛋白含量占全菌体蛋白含量的 15 %。结论　成功构建了粉尘螨Ⅰ类抗原cDNA基因的重组表达质粒pET32a( ) Derf 1,并在大肠杆菌中获得高效表达 ,为获得重组纯化Derf 1变应原并用于尘螨变应性疾病的诊治奠定基础     

粉尘螨主要变应原Derf1基因的改造与可溶性表达

目的在大肠杆菌中提高粉尘螨1类变应原（Derf1）的可溶性表达。方法用RT-PCR方法扩增得到Derf1的全长序列与成熟肽序列（mDerf1）；以已知DerP5基因的前导序列替换Derf1前导序列和原酶序列，重新构建出rDerf1基因；将上述3个基因分别克隆入原核表达载体pGEX-4T-1中表达，经Western-blot对三者的表达产物进行分析鉴定。结果Western-blot表明，pGEX-Derf1与pGEX-mDerf1的表达产物分别为分子量约63000与51000的重组蛋白质，重组蛋白质主要存在于细胞裂解液的沉淀中。pGEX-rDerf1大量表达了可溶性目的蛋白质，分子量约53000，并被成功地分离纯化。以上三种表达产物均可被鼠抗GST抗体与螨过敏患者血清特异地识别。结论表达了含Derf1，mDerf1与rDerf1的三种GST融合蛋白质，它们均具免疫反应性，纯化获得了GST-rDerf1融合蛋白质，为后期的诊断及治疗奠定了基础。     

Molecular cloning and characterization of full-length cDNAs encoding a novel high-molecular-weight Dermatophagoides pteronyssinus mite allergen, Der p 11

BACKGROUND: Dermatophagoides pteronyssinus (Dp) and D. farinae (Df) mites are the most important source of indoor aeroallergens. Most Dp mite allergens identified to date have relatively low molecular weights (MWs). Identification of high-MW mite allergens is a crucial step in characterizing the complete spectrum of mite allergens and to provide appropriate tools for diagnostic and therapeutic application. METHODS: The full-length Der p 11 cDNA clone was isolated using cDNA library immunoscreening, the 5'-3' rapid amplification of cDNA ends (RACE) system and polymerase chain reactions (PCR). The whole cDNA insert and its PCR-derived DNA fragments (p1 to p4) were generated and expressed in the Escherichia coli expression system. The allergenicity of the recombinant protein and its peptide fragments was examined by IgE immunodot assays. The IgE-binding reactivity of rDer p 11 was analyzed in the serum of 50 asthmatic children with positive reactivity to Dp mite extract. Its recombinant peptide fragments were also examined by immunodot assays in 30 mite-allergic children. RESULTS: Der p 11 cDNA consists of a 2625-bp open reading frame encoding a 103-kDa protein with 875 amino acids. It exhibits significant homology with the paramyosin of other invertebrates. The protein sequence alignment of this newly identified Dp mite allergen (denominated as Der p 11) revealed over 89% identity with Der f 11 and Blo t 1. Among 50 Dp-sensitive asthmatic children, rDer p 11 showed positive IgE-binding reactivity to 39 patients (78%). Using immunodot assays, multiple human IgE-binding activities were demonstrated in all four fragments of Der p 11. Using immunoblot assays, the dominant IgG-binding epitope for monoclonal antibody (mAb642) was located in fragment p3 only. In immunoblot assays, cross-inhibition between rDer p 11 and rDer f 11 was up to 73-80% at concentrations of 100 microg/ml. CONCLUSIONS: This study confirms that the newly identified recombinant Der p 11 is a novel and important high-MW Dp mite allergen for asthmatic children. Our data also indicates that human IgE-binding major epitopes are scattered over the entire molecule of Der p 11.     

粉尘螨变应原的分析

目的 对粉尘螨(Dermatophagoides farinae)变应原进行分离和鉴定其特异性变应原组分. 方法 采用ELISA检测粉尘螨变应原的生物活性.按常规方法制备粉尘螨浸出液,经SDS-PAGE分离,测定各组分的相对分子质量(M,);同时用对螨过敏的60例病人混合血清(建立血清库)作探针进行Westem blot,鉴定其特异性变应原组分. 结果 SDS-PAGE显示粉尘螨有15条蛋白带,Mr在14×103-109×103之间,其中主带有9条,M,分别为109×103、100×103、86×103、62×103、56×103、36×103、28 x103、19×103、14×103;Western blot结果表明,浸出液中共有5条致敏条带,其M,分别为109×103、100×103、36×103、28 x 103、14×103;经ELISA检测粉尘螨浸出液具有生物活性. 结论 粉尘螨的特异性变应原有5条,分别为109×103、100×103、36×103、28×103、14×103,其浸出液有稳定的生物活性.该研究为开发适合我国人群的粉尘螨标准化试剂提供了试验依据.     

Purification and Characterization of a Major Allergen from the House Dust Mite Dermatophagoides farinae

A major allergen from an extract of the house dust mite, Dermatophagoides farinae, was shown to be extremely heterogenic with respect to charge. A slightly basic component of this allergen with a pI of 8, was purified by isoelectric focusing in two steps. The purified component, denoted antigen 19/20 IIa, seemed to be representative for the allergenic activity of the major allergen. The amino acid analysis suggested that antigen 19/20 IIa had a molecular weight of 9400 and contained one residue of galactosamine. SDS polyacrylamide gel electrophoresis did indicate a somewhat higher molecular weight of 14,500. Antibodies against the purified component cross-reacted with a crude extract of the mite Dermatophagoides pteronyssinus.     

粉尘螨Ⅰ类变应原（DerfⅠ）的cDNA克隆及序列分析

目的 获得我国广州地区粉尘螨I类变应原（DerfI)cDNA片段,为构建DNA疫苗或表达重组蛋白打下基础。方法 挑取经选择鉴定的活粉尘螨,提取总RNA,采用RT-PCR的方法扩增DerfI片断,进行克隆、测序和分析。结果 获得长度为632个碱基对的核苷酸片断,序列分析结果和Genebank上去除内含子后的基因序列（emb|X65196.1|]同源性为99%,其中有6个碱基不同,推导的编码氨基酸序列同源性为100%。结论 我们首次获得广州地区的DerfI的cDNA克隆,该克隆cDNA序列与Genebank上已公布的DerfI序列高度同源。     

Altered antigenicity of M-177, a 177-kDa allergen from the house dust mite Dermatophagoides farinae, in stored extract

BACKGROUND: A high molecular weight allergen, M-177 (177 kDa) was isolated from Dermatophagoides farinae using a specific antibody raised to an allergenic clone Mag 3, which was obtained by immunoscreening a mite cDNA library. The potent IgE reactivity of M-177 is comparable with that of Der f 2. OBJECTIVE: The aim of this study was to analyse the molecular characteristics and the allergenic activity of M-177 in stored mite extracts. METHODS: Antigens were analysed by immunoblotting and enzyme-linked immunosorbent assay (ELISA; inhibition). Allergenic activity was estimated from IgE reactivity and the results of a histamine release assay. RESULTS: The intact M-177 molecule was present in high concentrations in fresh extract obtained from purified mite bodies, but was only detected in small amounts in stored extracts. Instead of the intact molecule, anti-Mag 3 antibody detected various cross-reactive antigens in the stored preparations. Studies of a stored liquid extract showed that these cross-reactive antigens were produced by the degradation of M-177, and that this change was suppressed by the addition of protease inhibitors. Interestingly, the allergenic activity of the fragmented M-177 (sM-177) isolated from the stored extracts was greater than that of the intact antigen. Specific IgE reacted with sM-177 in 84.2% of 38 sera samples from patients allergic to mites, while 65.8% were positive for M-177-specific IgE. Similarly, the histamine release test showed that sM-177 had greater allergenic activity in vitro. ELISA inhibition indicated that the increased allergenic activity resulted from alteration of the antigenicity with the degradation of M-177. CONCLUSIONS: M-177 is a protease-sensitive allergen. The breakdown products of M-177 provoked higher allergenic activity than the intact allergen.     

Cloning and sequencing of the group 6 allergen of Dermatophagoides pteronyssinus

Background The allergen Der p 6 from Dermatophagoides pteronyssinus has been described by substrate affinity as mite chymotrypsin. Objective The aim of this paper was to describe a cDNA clone encoding the allergen. Methods cDNA was cloned from a λ library using oligonucleotides published for Der p 6. Results The clone P6.1.1 had the N-terminal amino acid residues as reported for Der p 6, and at position 189 the Ser was conserved in chymotrypsin for substrate specificity as well as the catalytic triad of His57, Asp102 and Ser195 for serine proteases. The estimated Mr was 24.9K and it was 37% identical to the trypsin allergen Der p 3. Conclusion cDNA encoding Der p 6 has been described.     

粉尘螨抗细菌活性物质的分离与鉴定

目的从粉尘螨丙酮提取液中分离抗细菌活性成分,并对其抗菌活性进行初步鉴定。方法用丙酮抽提粉尘螨,并用Sephadex G50分子筛层析进行对粉尘螨提取液中的抗细菌活性进行初步分离、纯化。对各组分的抗细菌活性进行初步鉴定。结果经Sephadex G50分子筛层析分离得到Ⅰ及Ⅱ两个峰。粉尘螨丙酮粗提物对绿脓假单胞菌无抑制作用,但对金黄色葡萄球菌、枯草芽孢杆菌及短小芽孢杆菌均有抑制作用。峰Ⅰ及峰Ⅱ则对大肠埃希杆菌、枯草芽孢杆菌、短小芽孢杆菌及金黄色葡萄球菌都有抑制作用。粉尘螨粗提液及第二个峰在加热及蛋白酶K处理后仍然保留抗细菌活性,但是第一个峰在同样处理后失去了抗菌活性。结论首次从粉尘螨分离纯化得到抗细菌成分。     

Characterization of IgE and IgG Antibody Responses to Dermatophagoides farinae in Rats

Rats (Brown Norway/Wistar Fu) that were pretreated or not pretreated with cyclophosphamide were immunized with varying amounts of Dermatophagoides farinae allergen extract with alum as adjuvant. Sera were analysed by RAST and by crossed radioimmunoelectrophoresis (CRIE). The highest IgE antibody responses were recorded in animals pretreated with cyclophosphamide that had received low immunizing doses of antigen. The IgE antibody pattern in CRIE was, however, not influenced by the dose of antigen or by cyclophosphamide pretreatment. The IgG pattern in CRIE closely resembled the IgE pattern, demonstrating a similar specificity of the antibody responses of the two isotypes. This indicates non-class specific control of the specificity of antibody responses.     

Comparisons of IgE, IgG, and IgG4 responsiveness to Dermatophagoides farinae in children by immunoblotting

Although asthmatic children are often sensitized to the house-dust mite (HDM) during early childhood, it is not clear what antigenic components are associated with the early immune response of these children. To investigate this problem, we evaluated IgE, IgG, and IgG4 antibody responses to Dermatophagoides farinae (Df) by immunoblotting among three groups of children: group I aged 0–4 years, group II aged 5–9 years, and group III aged 10–14 years. In the group I subjects, positive IgE-binding reactions to 15- and 25-kDa components were found in 76% and 44% of sera, respectively. Those to other components were generally low in frequency. In contrast, positive IgG-binding reactions to 15- and 25-kDa components were found in 44% and 24% of sera, and those to 30- and 110-kDa components in 48% and 88% of sera, respectively. Positive IgG4 reactions to 15- and 25-kDa components were found in 48% and 24%, respectively, and those to other components were very low. Positive IgE-binding reactions to these components gradually became more frequent with increasing age in groups II and III, while IgG and IgG4 reactivities were not markedly different in these age groups. These results suggest that the 15- and 25-kDa proteins of Df are important antigens associated with the initial IgE response to HDM in early childhood, while the 30- and 110-kDa proteins are associated with IgG and 15-kDa components with IgG4.     

粉尘螨变应原第5组分基因克隆及分子特征分析

目的 获得粉尘螨变应原第5组分的编码基因(Der f5)并了解其分子特征.方法 用RNAiso试剂盒提取粉尘螨总RNA,根据GenBank已公布的Der f5核酸序列设计引物,用RT-PCR扩增获得其编码基因,插入pMD19-T Simple载体进行序列测定和分析.结果 获得的Der f5基因与参考序列(GenBank AY283283)同源性达97.8%,含1个完整的开放阅读框架(ORF),由132个氨基酸组成,信号肽位于1～19AA、跨膜区域位于1～19AA,为细胞外疏水性蛋白.二级结构由延伸主链(1.52%)、无规则卷曲(7.58%)和α螺旋(90.91%)组成.具有酪蛋白激酶Ⅱ磷酸化位点2个.其氨基酸序列与屋尘螨变应原第5组分相似率为78%.结论 成功克隆了 Der f5,并初步预测得其分子特征.     

Localization of a major allergen, Der p 2, in the gut and faecal pellets of Dermatophagoides pteronyssinus

BACKGROUND: The house dust mite Dermatophagoides ptronyssinus is one of the most significant indoor sensitizing agents of allergy. Allergen localization may indicate the importance of secreted materials, faeces, and nonexcreted mite body components as allergen sources. OBJECTIVE: This study attempted to localize the sites and concentrations of Der p 2 in the cryostat sections of D. pteronyssinus using antirecombinant Der p 2 monoclonal antibody. METHODS: Male and female mites and mite faeces collected separately from both sexes were used. Live mites were embedded and serial cryostat sections for light microscopy were performed. Anti-recombinant Der p 2 monoclonal antibody previously produced by the authors was used. For immunoprobing, mite cryostat sections were incubated in the following antibody-containing solutions: monoclonal antibody against Der p 2 was initially applied to the sections and fluorescent isothiocyanate conjugated antimouse immunoglobulin G was reacted as the secondary antibody. The faecal pellets were treated the same as described above. RESULTS: Immunofluorescent probing of cryostat sections with the monoclonal antibody showed labelling of the gut lining, gut contents and defecated faecal pellets. No other internal organs were identified as positively labelled. CONCLUSION: This study suggested that a major allergen, Der p 2, found in the house dust mite D. pteronyssinus is derived from the digestive tract and concentrated in the faeces.     

Characterization of Allergens in a Crude Extract of Dermatophagoides farinae and Their Identification in a New Purified Preparation

The allergens of a crude D. farinae extract were identified by means of crossed radioimmunoelectrophoresis (CRIE). A total of 11 allergens were identified. They were characterized as three major, three intermediate and five minor allergens, based on radiostaining in CRIE. In addition to the radiostaining due to allergens, some misleading radiostaining was observed associated with some of the other antigens. A purified commercially available preparation, Spectralgen Mite D. farinae, was compared with the crude extract by means of immunoelectrophoretic techniques and radioallergosorbent test (RAST) based techniques. The purified preparation was found to be fully representative of the allergens in the crude extract. All 11 allergens were identified in the purified preparation. The purification ratio of the allergens varied from 2 to 7, while the total specific allergenic activity was approximately 6 times higher in the purified preparation than in the crude extract, as judged from RAST-inhibition studies.     

Localization of Der f 2 in the gut and fecal pellets of Dermatophagoides farinae

BACKGROUND: House dust mite derived materials are known to be the most potent agent inducing allergic diseases. Localization of Der f 2 was attempted to specify the sites and concentrations of Der f 2 within the mite, which may indicate the importance of secreted materials and nonexcreted body components as allergen sources. METHODS: Serial cryostat sections of embedded live mites and the fecal pellets, collected by brush, were immunoprobed using monoclonal antibody (mAb) 2F38 raised against recombinant (r) Der f 2. RESULTS: Highest concentrations were found in the anterior midgut, implying that this is the site of Der f 2 synthesis and secretion. Digestive material and defecated fecal pellets were also labeled with mAb. CONCLUSIONS: Our results show that the major allergen, Der f 2, found in the house dust mite D. farinae is derived from the digestive tract, and is concentrated in the feces.