Hong X Q, Santiago Mejia J, Kumar S, Perler F B, Carlow C K
New England Biolabs, Beverly, MA, USA.
Parasitology. 1996 Mar;112 ( Pt 3):331-8. doi: 10.1017/s0031182000065859.
Dirofilaria immitis is an important filarial parasite of dogs and cats, and a useful model for human filariasis. Current diagnostic tests for heartworm infection in animals rely on the presence of fecund female worms (usually found 6.5 months post-infection or later) and therefore fail to detect pre-patent infections. Putative pepsin inhibitors from 2 filarial parasites of humans namely Onchocerca volvulus (Ov33, Oc3.6, OvD5B) and Brugia malayi (Bm33), have been shown to be useful in diagnosis of onchocerciasis and lymphatic filariasis, respectively. Previous studies have suggested that a homologue exists in D. immitis (DiT33), which may have potential in diagnosis of heartworm infection. In this study, the isolation and characterization of a cDNA clone encoding DiT33 is described. This cDNA contains 12 bases of the nematode-specific 22 nucleotide spliced leader sequence and encodes a 26.4 kDa-protein with a high level of similarity (87-89%) to other filarial members of the family. DiT33 was over-expressed in E. coli as a fusion with the maltose-binding protein and serological analysis was performed using a panel of clinically defined dog sera. The findings of this study indicate that DiT33 is a promising antigen for the early detection of D. immitis and may be a valuable tool in the control and management of heartworm infection.
犬恶丝虫是犬猫重要的丝虫寄生虫，也是人类丝虫病的有用模型。目前用于动物心丝虫感染的诊断测试依赖于成熟雌虫的存在（通常在感染后6.5个月或更晚发现），因此无法检测到感染前期。来自两种人类丝虫寄生虫即盘尾丝虫（Ov33、Oc3.6、OvD5B）和马来布鲁线虫（Bm33）的假定胃蛋白酶抑制剂，已分别被证明可用于盘尾丝虫病和淋巴丝虫病的诊断。先前的研究表明犬恶丝虫中存在一种同源物（DiT33），它可能在心丝虫感染的诊断中具有潜力。在本研究中，描述了编码DiT33的cDNA克隆的分离和鉴定。该cDNA包含线虫特异性22个核苷酸剪接前导序列的12个碱基，并编码一种26.4 kDa的蛋白质，与该家族的其他丝虫成员具有高度相似性（87-89%）。DiT33在大肠杆菌中作为与麦芽糖结合蛋白的融合蛋白进行过表达，并使用一组临床确诊的犬血清进行血清学分析。本研究结果表明，DiT33是早期检测犬恶丝虫的一种有前景的抗原，可能是控制和管理心丝虫感染的一种有价值的工具。
