异种移植领域猪内源性逆转录病毒的研究进展

供体器官来源不足严重阻碍和困扰着器官移植手术的推广和应用，随着免疫学、基因工程与克隆技术的迅速发展，转基因猪的出现，异种移植有望解决器官短缺的问题，但猪内源性逆转录病毒种间传播的可能性必须进一步深入研究，本文就近期相关研究作一综述。     

实时荧光定量RT-PCR法建立版纳微型猪近交系中厚皮创面转化生长因子表达体系

背景：版纳微型猪近交系能较好的模拟人取皮区创面,构建动物模型,检测与创面愈合及瘢痕形成密切相关的转化生长因子的表达。 目的：观察创面愈合过程中转化生长因子β1基因的表达情况。 方法：利用版纳微型猪近交系4~6月龄猪构建了皮肤创面愈合动物模型,通过提取皮肤创面总RNA,设计特异引物,对与创面愈合相关密切的转化生长因子β1基因进行了RT-PCR扩增。纯化目的片段并与pMD18-T载体连接,转化宿主菌DH5α,提取重组质粒DNA,并经酶切、PCR和测序鉴定,计算重组质粒原液拷贝数浓度并制备梯度浓度标准品,进行实时荧光定量PCR。 结果与结论：建立的转化生长因子β1基因mRNA表达实时荧光定量PCR检测方法特异性较好,检测灵敏度可达10³拷贝/µL,线性范围达10³~10⁹拷贝/µL,阈值循环数与PCR体系中起始模板量的对数值之间存在良好的线性关系(R2=0.988),扩增效率高(E=107.433%)。利用该检测体系检测了45份样品,效果良好,该方法可为研究TGF-β1基因在创面愈合过程中的作用机理奠定分子生物学基础。     

异种移植领域猪内源性逆转录病毒的研究进展

供体器官来源不足严重阻碍和困扰着器官移植手术的推广和应用,随着免疫学、基因工程与克隆技术的迅速发展,转基因猪的出现,异种移植有望解决器官短缺的问题,但猪内源性逆转录病毒种间传播的可能性必须进一步深入研究,本文就近期相关研究作一综述.     

版纳微型猪近交系SLA-DOA 基因克隆、mRNA 表达及蛋白质功能生物信息学分析

目的:克隆版纳微型猪近交系(Banna mini-pig inbred line,BMI)白细胞抗原DO 座位alpha 亚基(SLA-DOA)的编码序列,并对其19 个重要组织mRNA 表达作半定量分析。方法:RT-PCR 方法获得SLA-DOA 的全长cDNA 序列;半定量RT-PCR 方法分析其在BMI 重要组织的mRNA 表达谱,并运用生物信息学对其核酸及蛋白序列进行分析,构建系统进化树。结果:BMI SLA-DOA cDNA 长度为1 079 bp,编码250 个氨基酸,蛋白质分子量为27.81 kD,等电点为6.48;位于猪7 号染色体,由4 个外显子和3 个内含子构成;其mRNA 高表达于淋巴结和胃,低表达于心脏、皮肤和十二指肠,在其他14 种组织中不表达;SLA-DOA 蛋白存在1 个信号肽,1 个跨膜螺旋,3 个保守域,4 个O 连接的糖基化位点,18 个磷酸化位点,位于细胞质的概率是94.1%;系统进化分析表明,在所选择的6 个物种中,BMI(猪)与牛的亲缘关系最近。结论:本研究成功克隆了版纳微型猪近交系SLA-DOA 基因并进行了生物信息学功能分析和多种组织表达分析,为版纳微型猪近交系的异种器官移植研究奠定基础。     

猪内源性逆转录病毒在异种移植中的感染风险

猪作为异种移植供体可有效解决人类同种移植供体短缺的问题,但猪内源性逆转录病毒具有潜在的感染风险,严重影响了猪器官、组织、细胞在临床中的应用。因此,在异种移植应用于临床前,阐明猪内源性逆转录病毒的感染风险性至关重要。     

壳聚糖纳米纤维支架对猪肝细胞分泌猪内源性逆转录病毒的影响

探讨壳聚糖纳米纤维支架对肝细胞的PERV分泌量以及其感染性的影响。将新鲜分离的猪肝细胞接种于壳聚糖纳米纤维支架或普通条件下连续培养7 d,分为实验组(Nano组)和对照组(Hep组)。每天收集培养液检测逆转录酶(RT)活性,并通过RT-PCR和实时定量PCR测定PERV RNA水平。通过western blot检测细胞裂解液中PERV gag 30蛋白含量。细胞培养液体外孵育HEK293细胞以测定其感染性。结果表明:实时定量PCR、RT活性以及western blot具有相似的变化趋势。在体外培养10 h和2 d出现PERV分泌高峰然后逐渐下降。除第6 dPERV RNA水平和第5 d蛋白水平实验组明显高于对照组外,其余均无明显差异。体外感染实验无HEK293细胞感染。壳聚糖纳米纤维支架会延长猪肝细胞的PERV分泌时间但对分泌量以及体外感染性并无明显影响,可安全用于生物人工肝。     

猪内源性逆转录病毒体外感染人胚肾细胞系HEK-293的初步研究

目的对猪内源性逆转录病毒(PERV)体外感染人胚肾细胞系HEK-293的能力进行检测。方法建立体外感染人胚肾细胞系HEK-293的方法,用免疫电镜的方法观察PERV粒子,聚合酶链反应(PCR)、逆转录聚合酶链反应(RT—PCR)检测与PERV共培养24h后HEK-293细胞基因组中PERV前病毒基因的整合、表达并对PERV亚型进行鉴定,激光共聚焦显微镜检测PERV—gag蛋白的表达并进行定量分析。结果电镜下可观察到PERV的圆形病毒粒子;与PERV共培养24h后HEK-293细胞基因组中检测到PERV前病毒DNA,且mRNA也有效表达,PERV亚型为PERV—A,B型;激光共聚焦显微镜观察到PERV—gag蛋白在感染细胞HEK-293的胞质表达,但表达量下降。结论PERV具有体外感染人胚肾细胞系HEK-293的能力,病毒蛋白可以有效表达,因此在猪到人的异种器官移植研究中对PERV可能引起的人兽共患病进行安全性评价是极有必要的。     

促甲状腺素化学发光免疫定量检测试剂盒的研制

目的:研制人血清中促甲状腺素(TSH)的化学发光免疫检测试剂盒.方法:采用辣根过氧化物酶标记的抗TSHβ亚单位特异性单克隆抗体(mAb),与固相包被的抗TSHα亚单位的另一mAb配对,以鲁米诺作为底物,采用两步法建立了双位点夹心法人血清TSH的化学发光免疫定量分析法.结果:该方法灵敏度为0.0788 mIU/L,批内CV平均为4.7%,批间CV平均为8.4%,平均回收率为93.05%.该检测与LH、FSH和HCG无交叉反应.部分实验样品的测试结果显示该试剂与国外同类试剂(雅培architect i2000)的测定结果明显相关(r＝0.984).结论:该方法具有较高的灵敏度、重复性和准确度,与其他同类产品相比简便、快捷、成本低,适于临床检测和科研应用.     

高效抗逆转录病毒治疗对中国HIV/AIDS患者淋巴细胞活化及第二受体表达的影响

目的　了解高效抗逆转录病毒治疗后中国HIV/ AIDS患者淋巴细胞活化及CCR5、CXCR4表达的变化,探讨HIV感染者对于抗病毒治疗的免疫应答。方法　10例HIV /AIDS患者给予高效抗逆转录病毒治疗(HAART),用流式细胞仪检测治疗前和治疗第3、6 个月T淋巴细胞活化(HLA DR、CD38表达)及第二受体CCR5、CXCR4表达情况,比较HIV/ AIDS患者治疗前后淋巴细胞活化、第二受体表达的变化。结果　治疗前,10例HIV /AIDS患者CD4+、CD8+ T淋巴细胞活化水平均明显高于健康对照,CD8+ T淋巴细胞表面CCR5的表达明显高于健康对照,CXCR4 的表达明显低于健康对照(P<0.05);HAART治疗后,患者淋巴细胞活化水平随治疗时间明显下降(P<0.05),CD8+ T淋巴细胞表面CCR5表达水平显著降低(P< 0. 01), CXCR4 的表达升高;治疗6 个月时, CD38 CD4、HLA DRCD38 CD4、CCR5 CD8、CXCR4 CD8表达水平恢复至健康人水平;HIV AIDS淋巴细胞活化水平及第二受体CCR5的表达降低与HAART治疗后CD4+T淋巴细胞数量的升高具有显著的相关性。结论HAART能够降低中国HIV /AIDS患者淋巴细胞活化水平,使第二受体表达水平趋于正常,促进免疫功能的恢复。     

Development of sensitive methods for detection of porcine endogenous retrovirus-C (PERV-C) in the genome of pigs

Porcine endogenous retroviruses (PERV) represent a risk for xenotransplantation using pig cells, tissues or organs. PERV-A and PERV-B are present in the genome of all pigs and both infect human cells in vitro. PERV-C infects only pig cells and it is integrated in the genome of most, but not all pigs. Recombinants between PERV-A and PERV-C were described that infect human cells and replicate at high titres. To avoid such recombinations, PERV-C positive animals should not be used for breeding animals suited for xenotransplantation.In order to detect PERV-C positive pigs, different methods were developed such as specific PCRs using different primers, a highly sensitive nested PCR and a real-time PCR allowing measurement of proviral copy numbers. The real-time PCR was found to be useful to discriminate between contamination and actual provirus copies. The PCRs were optimized and their sensitivity was determined. Screening can be started with PCR1, if the result is negative, PCR2 to PCR5 or the nested PCR should be used, if the result is positive, the real-time PCR should be used to exclude contaminations. All methods were used to evaluate the prevalence of PERV-C and to identify PERV-C free animals. Due to the risk of contamination with cells from other animals testing should be performed with blood cells, not with ear biopsies.     

Functional hierarchy of two L domains in porcine endogenous retrovirus (PERV) that influence release and infectivity

The porcine endogenous retrovirus (PERV) Gag protein contains two late (L) domain motifs, PPPY and P(F/S)AP. Using viral release assays we demonstrate that PPPY is the dominant L domain involved in PERV release. PFAP represents a novel retroviral L domain variant and is defined by abnormal viral assembly phenotypes visualized by electron microscopy and attenuation of early PERV release as measured by viral genomes. PSAP is functionally dominant over PFAP in early PERV release. PSAP virions are 3.5-fold more infectious in vitro by TCID(50) and in vivo results in more RNA positive tissues and higher levels of proviral DNA using our human PERV-A receptor (HuPAR-2) transgenic mouse model [Martina, Y., Marcucci, K.T., Cherqui, S., Szabo, A., Drysdale, T., Srinivisan, U., Wilson, C.A., Patience, C., Salomon, D.R., 2006. Mice transgenic for a human porcine endogenous retrovirus receptor are susceptible to productive viral infection. J. Virol. 80 (7), 3135-3146]. The functional hierarchies displayed by PERV L domains, demonstrates that L domain selection in viral evolution exists to promote efficient viral assembly, release and infectivity in the virus-host context.     

Multiplex high resolution melting assay for estimation of Porcine Endogenous Retrovirus (PERV) relative gene dosage in pigs and detection of PERV infection in xenograft recipients

Porcine Endogenous Retrovirus (PERV) poses an infectious risk in the field of xenotransplantation. This risk may be mitigated by breeding selectively animals bearing favorable PERV genetic characteristics including pigs with low levels of PERV integrated in the genome. A real-time quantitative polymerase chain reaction (PCR) assay employing the Roche High Resolution Melting (HRM) Master was used to estimate the relative gene dosage of PERV pol integrated within the pig genome. When assessed across 99 pigs of the Auckland Island breed numerous animals bearing low gene dosage were identified. The assay was adapted further to perform multiplex PCR for the detection of PERV infection within xenograft recipients. Besides PERV, amplification targets for the multiplex PCR include a pig cell marker for the determination of microchimerism and an internal amplification control (IAC) to assess the efficiency of nucleic acid isolation and effects of PCR inhibition. When 12 patients who had received porcine islet transplants were tested no evidence of PERV infection was found. The assay was shown to be specific, highly reproducible with superior performance over conventional nested PCR. This assay can be used as both a screening tool for PERV proviral levels within donor pigs and as a diagnostic tool to examine PERV transmission in human patients treated with porcine xenotransplantation material.     

Large Number of Polymorphic Nucleotides and a Termination Codon in the env Gene of the Endogenous Human Retrovirus ERV3

The terminal portion of the pol gene and the entire env gene of the human endogenous retrovirus ERV3 was screened for polymorphic nucleotides. For this purpose fragments amplified from the desired regions of ERV3 were subjected to single strand conformational analysis (SSCP analysis). Using this approach, we detected 13 polymorphic nucleotides, namely four in the pol gene and nine in the env gene. Three of the nucleotide substitutions were synonymous (not affecting the amino acid code). One of the non-synonymous nucleotide substitutions changed an arginine codon to a termination codon. The alleles at the different polymorphic sites could be arranged into five ERV3 haplotypes, two of which were new.To evaluate the possible significance of the termination codon, which precludes expression of a putative immunoregulatory factor, we examined samples of DNA from patients with multiple sclerosis, a demyelinating disease of presumed autoimmune etiology. We did not find an association between the ERV3 allele with the termination codon and this disease. Perhaps the presence of a stop codon combined with the high number of non-synonymous nucleotide substitutions in the reading frame of the env gene reflects absence of selective constraints during evolution. Obviously, our findings contradict the assumption that the reading frame of the ERV3 env gene has been conserved throughout evolution.     

Comparison of the convergent receptor utilization of a retargeted feline leukemia virus envelope with a naturally-occurring porcine endogenous retrovirus A

In vitro screening of randomized FeLV Envelope libraries identified the CP isolate, which enters cells through HuPAR-1, one of two human receptors utilized by porcine endogenous retrovirus-A (PERV-A), a distantly related gammaretrovirus. The CP and PERV-A Envs however, share little amino acid homology. Their receptor utilization was examined to define the common receptor usage of these disparate viral Envs. We demonstrate that the receptor usage of CP extends to HuPAR-2 but not to the porcine receptor PoPAR, the cognate receptor for PERV-A. Reciprocal interference between virus expressing CP and PERV-A Envs was observed on human cells. Amino acid residues localized to within the putative second extracellular loop (ECL-2) of PAR-1 and PAR-2 are found to be critical for CP envelope function. Through a panel of receptor chimeras and point mutations, this area was also found to be responsible for the differential usage of the PoPAR receptor between CP and PERV-A.     

The in vitro inhibitory effect of human neutrophil peptide-1 on human immunodeficiency virus type 1

Humanimmunodeficiency virus (HIV) has beeni-dentified asthe etiologically agent of the worldwidedisaster disease ,acquired immunodeficiency syn-drome (AIDS) . Highly active anti-retrovirus ther-apy (HAART) ,especiallytriple-drug combinationregime has provedto be very beneficial tothosein-fected with HIV. However ,their value of benefitsis limited on account of the rapid development ofviral resistance and the toxicity involved.For thisreason,it necessitates continuation to search fornewdr…     

非小细胞肺癌中端粒酶催化基团mRNA表达的临床意义及其与P53的相关性

目的:研究非小细胞肺癌与正常肺组织穿刺标本中端粒酶催化基团mRNA表达与肿瘤分期与分级关系,探讨其在非小细胞肺癌早期诊断中的临床意义.观察肿瘤抑制基因P53与hTRT mRNA表达的关系.方法:采用原位杂交技术检测非小细胞肺癌与正常肺组织中端粒酶催化基团mRNA表达;用免疫组化方法检测非小细胞肺癌的P53蛋白表达.结果...     

XW630对大鼠成骨细胞雌激素受体基因表达的影响

探讨抗骨质疏松新化合物XW630促进成骨作用的机理。从SD大鼠颅骨中分离培养成骨细胞，首次采用具有高灵敏度的逆转录—聚合酶链反应(RT—PCR)技术直接从大鼠成骨细胞中检测雌激素受体mRNA的表达。结果表明，XW630具有促进成骨细胞ERmRNA表达的作用，且呈时间依赖性。在相同浓度(10^-4mol／L)条件下，XW630作用强于四环素加哌嗪雌酮及单纯雌酚酮。XW630可能通过对ER基因表达的影响而在骨代谢中起作用。