Cheong Nge, Ramos John Donnie A, Tang Chwee Ying, Chng Hiok Hee, Yao Rong, Liang Zongan, Lee Bee Wah, Chua Kaw Yan
Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Int Arch Allergy Immunol. 2009;149(1):25-32. doi: 10.1159/000176303. Epub 2008 Nov 26.
Blomia tropicalis is an important domestic dust mite in the tropics and subtropics. This study describes cDNA cloning of the group 4 allergen of B. tropicalis, and the evaluation of the sensitization of this allergen in atopic populations from 2 geographic regions.
cDNA cloning was carried out using the Smart RACE cDNA amplification kit. The full-length Blo t 4 cDNA was isolated by cDNA library screening, 5' and 3' rapid amplification of cDNA ends and long-distance PCR. Sequence analysis was performed with a combination of the Clustal W, CGC and Blast program packages. The cDNA was expressed in Pichia pastoris yeast. The skin prick test was used to evaluate the sensitization profile of recombinant Blo t 4, crude dust mite allergen extracts and major B. tropicalis recombinant allergen Blo t 5.
The cloned Blo t 4 had a molecular weight of 56 kDa and had 68% amino acid homology with group 4 allergens of Dermatophagoides pteronyssinus and 65% with those of Euroglyphus maynei. A sensitization profile to the expressed recombinant Blo t 4 allergen (28%) showed an unusually higher frequency than to the major allergen Blo t 5 (22%) in allergic subjects from Chengdu, PR China. In comparison, the subjects from Singapore showed very low sensitization to Blo t 4 (4%) compared with Blo t 5 (84%).
Group 4 allergens of B. tropicalis may be an important dust mite allergen in certain distinct populations.
热带无爪螨是热带和亚热带地区一种重要的室内尘螨。本研究描述了热带无爪螨4组变应原的cDNA克隆，并评估了该变应原在两个地理区域特应性人群中的致敏情况。
使用Smart RACE cDNA扩增试剂盒进行cDNA克隆。通过cDNA文库筛选、5'和3' cDNA末端快速扩增以及长距离PCR分离出全长Blo t 4 cDNA。结合Clustal W、CGC和Blast程序包进行序列分析。该cDNA在毕赤酵母中表达。采用皮肤点刺试验评估重组Blo t 4、粗制尘螨变应原提取物和主要热带无爪螨重组变应原Blo t 5的致敏情况。
克隆的Blo t 4分子量为56 kDa，与粉尘螨4组变应原的氨基酸同源性为68%，与梅氏嗜霉螨的同源性为65%。在中国成都的过敏受试者中，对表达的重组Blo t 4变应原的致敏率（28%）显示出比主要变应原Blo t 5（22%）异常高的频率。相比之下，新加坡的受试者对Blo t 4的致敏率（4%）与Blo t 5（84%）相比非常低。
热带无爪螨4组变应原可能是某些特定人群中一种重要的尘螨变应原。
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