异嗜性小鼠白血病病毒相关病毒（XMRV）与人类疾病的相关性研究进展*

异嗜性小鼠白血病病毒相关病毒(XMRV)是第一个能够感染人的γ型逆转录病毒。由于逆转录病毒具有插入宿主染色体引发基因突变的特性,以及部分γ型逆转录病毒携带原癌基因并能诱发癌症,致使XMRV感染与人类癌症发病之间的关系受到广泛关注。西方研究表明XMRV感染与前列腺癌和慢性疲劳综合症的发病有一定的相关性,因此成为研究热点。但各地报告的检测结果却不尽相同,甚至有矛盾之处。XMRV致瘤性可能是能够激活内源性原癌基因,从而导致细胞转化。在我国,目前尚未见XMRV感染与人类疾病关系的相关研究报道。XMRV感染的地区间或人群间差异性也有待研究。其感染的途径及临床可普及应用的检测手段也未被阐明,在我国不同地区不同类型人群中的感染率、与疾病的关系、对我国人口健康的潜在影响,均有待研究。     

Identification, expression and characterisation of a major salivary allergen (Cul s 1) of the biting midge Culicoides sonorensis relevant for summer eczema in horses

Salivary proteins of Culicoides biting midges are thought to play a key role in summer eczema (SE), a seasonal recurrent allergic dermatitis in horses. The present study describes the identification, expression and clinical relevance of a candidate allergen of the North American midge Culicoides sonorensis. Immunoblot analysis of midge saliva revealed a 66 kDa protein (Cul s 1) that was bound by IgE from several SE-affected (SE+) horses. Further characterisation by fragmentation, mass spectrometry and bioinformatics identified Cul s 1 as maltase, an enzyme involved in sugar meal digestion. A cDNA encoding Cul s 1 was isolated and expressed as a polyhistidine-tagged fusion protein in a baculovirus/insect cell expression system. The clinical relevance of the affinity-purified recombinant Cul s 1 (rCul s 1) was investigated by immunoblotting, histamine release testing (HRT) and intradermal testing (IDT) in eight SE+ and eight control horses. Seven SE+ horses had rCul s 1-specific IgE, whereas only one control animal had IgE directed against this allergen. Furthermore, the HRT showed rCul s 1 induced basophil degranulation in samples from seven of eight SE+ horses but in none of the control animals. rCul s 1 also induced immediate (7/8), late-phase (8/8) and delayed (1/8) skin reactivity in IDT on all SE+ horses that had a positive test with the whole body extract (WBE) of C. sonorensis. None of the control horses showed immediate or delayed skin reactivity with rCul s 1, and only one control horse had a positive late-phase response, while several non-specific late-phase reactions were observed with the insect WBE. Thus, we believe rCul s 1 is the first specific salivary allergen of C. sonorensis to be described that promises to advance both in vitro and in vivo diagnosis and may contribute to the development of immunotherapy for SE in horses.