通过暂时免疫抑制研究跨膜蛋白C末端缺失对EIAV疫苗株EIAV_(FDDV12)体内复制的影响  

Transient immune suppression of inapparent carrier poniesinoculated with attenuated equine infectious anemiavirus infectious clone

作　　者：姜成刚[1,2] 马建 林跃智[2] 赵立平[2] 吕晓玲[2] 华育平[3] 刘娣 周建华[2] 

机构地区：[1]黑龙江省农业科学院畜牧研究中心博士后工作站,黑龙江哈尔滨150086 [2]中国农业科学院哈尔滨兽医研究所兽医生物技术国家重点实验室/大动物病研究室,黑龙江哈尔滨150001 [3]东北林业大学博士后流动站,黑龙江哈尔滨150086

出　　处：《中国预防兽医学报》2010年第11期829-833,共5页Chinese Journal of Preventive Veterinary Medicine

基　　金：十一五重大传染病专项(2008ZX1001-1010);国家自然科学基金(30771994;30901349);黑龙江省博士后基金项目(LBH-Z08017)

摘　　要：马传染性贫血病毒(EIAV)减毒疫苗是世界首例慢病毒疫苗,但其作用机理尚不明了。我们的前期研究发现EIAV疫苗株EIAVFDDV12编码跨膜蛋白gp45的基因在马体内发生高频率G2230A点突变形成终止子,使该蛋白C末端出现154个氨基酸的截短。为了探讨该截短蛋白对EIAV疫苗株生物学特性的作用,本研究以EIAV弱毒疫苗株感染性克隆基础上,构建了gp45截短型感染性克隆,脂质体转染细胞,增殖传代,获得病毒株EIAVFDDVTM-36,接种到马体内。在接种后167 d内未观察到临床症状,连续注射10 d地塞米松以暂时抑制免疫系统,并用迟发性超敏反应和淋巴细胞增殖实验评价免疫抑制效果。结果显示,截短型跨膜蛋白疫苗株EIAVFDDVTM-36接种组免疫抑制前后病毒载量和中和抗体效价差异不显著,而完整型跨膜蛋白疫苗株感染性克隆EIAVFDDVTM-45接种组4匹马中3匹免疫抑制后病毒载量显著上升,同时组内中和抗体效价明显提高。以上结果表明,马体特异性免疫压力对EIAVFDDVTM-36复制无影响,而对亲本株EIAVFDDVTM-45复制有抑制,显示跨膜蛋白截短型EIAV作为疫苗更为安全。但免疫抑制造成的gp45跨膜蛋白未截短型疫苗株感染性克隆体内病毒载量升高,可以促使机体产生更高的中和抗体效价,提示该疫苗的安全性和有效性在一定程度内呈负相关(相互制约)。因此,安全性和有效性的平衡是慢病毒减毒疫苗研发需注意的重要因素。Equine infectious anemia virus （EIAV） vaccine is the first lentiviral vaccine with a successful application, but itsmechanism on inducing protective immunity remains unclear. Our previous studies found that the gene encoding transmembraneprotein （gp45） of EIAV vaccine strain EIAVFDDV12 had a high-frequent G2230A mutation to create a stop coding, resulting in atruncation of 154 amino acid residues at the C-terminus. To explore the biological meaning of the gp45 truncation, a molecularclone EIAVFDDVTM-36 with truncated gp45 was constructed using EIAVFDDVTM-45 as the backbone. Eight ponies were randomly groupedand inoculated with either EIAVFDDVTM-36 or EIAVFDDVTM-45 and transient immune suppression was induced by daily injection ofdexamethasone for 10 days. The results showed that treatment of dexamethasone did not appear to alter the plasma viral loads andserum neutralizing antibody activities in EIAVFDDVTM-36-inoculated ponies, however it significantly increased plasma viral loads inthree of four EIAVFDDVTM-45-inoculated ponies after the transient immune suppression were observed. Furthermore, the treatment ofdexamethasone significantly enhanced the serum neutralizing activity of the EIAVFDDVTM-45 group of ponies （p0.05）. It appeared thatspecific immune pressure had no effect on EIAVFDDVTM-36 replication in vivo, rather limited the production EIAVFDDVTM-45, implicatingan elevated safety of EIAVFDDVTM-36 as an EIAV vaccine. On the other hand, the increased plasma viral loads and a higherneutralization antibody activity in EIAVFDDVTM-45-inoculated ponies indicated that the protection efficacy and the safety of EIAVattenuated vaccines may be negatively correlated. Therefore, it was important to carefully balance these two criteria of lentiviralvaccines.

关 键 词：马传染性贫血病毒 跨膜蛋白 截短突变 体内复制 免疫抑制 

分 类 号：S852.65[农业科学—基础兽医学]