The full-length E1E4 protein of human papillomavirus type 18 modulates differentiation-dependent viral DNA amplification and late gene expression

Activation of the productive phase of the human papillomavirus (HPV) life cycle in differentiated keratinocytes is coincident with high-level expression of E1E4 protein. To determine the role of E1E4 in the HPV replication cycle, we constructed HPV18 mutant genomes in which expression of the full-length E1E4 protein was abrogated. Undifferentiated keratinocytes containing mutant genomes showed enhanced proliferation when compared to cells containing wildtype genomes, but there were no differences in maintenance of viral episomes. Following differentiation, cells with mutant genomes exhibited reduced levels of viral DNA amplification and late gene expression, compared to wildtype genome-containing cells. This indicates that HPV18 E1E4 plays an important role in regulating HPV late functions, and it may also function in the early phase of the replication cycle. Our finding that full-length HPV18 E1E4 protein plays a significant role in promoting viral genome amplification concurs with a similar report with HPV31, but is in contrast to an HPV11 study where viral DNA amplification was not dependent on full-length E1E4 expression, and to HPV16 where only C-terminal truncations in E1E4 abrogated vegetative genome replication. This suggests that type-specific differences exist between various E1E4 proteins.     

重组人乳头瘤病毒16型E6蛋白的表达、纯化和动物免疫效果分析

目的 诱导表达人乳头瘤病毒16型(HPV16)E6蛋白,制备可溶性蛋白,并通过动物免疫进行免疫效果评估.方法 采用IPTG诱导pQE30-HPV16E6/BL21(DE3)重组菌株,表达产物经SDS-PAGE和Western blot分析鉴定.提取包涵体进行变性处理,变性蛋白经Ni2+金属螯合层析纯化,将纯化产物用复性透析方法处理以获取可溶性蛋白.免疫Bal B/c小鼠,检测血清抗体、CD4+/CD8+和IFN-γ.结果 诱导后重组菌有相对分子量18 000蛋白质表达,以不溶性包涵体为主要表达方式.目的蛋白可与HPV16E6多克隆抗体识别,纯化和透析处理后得到可溶性的蛋白.小鼠免疫后血清抗体滴度升高,淋巴细胞CD4+/CD8+升高,IFN-γ未见升高.结论 成功表达了HPV16E6蛋白,同时处理包涵体并制备了可溶性目的蛋白.目的蛋白可刺激小鼠体内产生有效的免疫反应,该蛋白的成功制备为患者血清抗体的检测和肿瘤细胞杀伤的免疫研究奠定了坚实基础.     

Activities of human papillomavirus 16 E6 natural variants in human keratinocytes

Genetic variations in the E6 oncogene have been associated with different risk for cancer progression. In the present study, the functional significance of human papillomavirus (HPV) polymorphism in the E6 oncogene was investigated. Ten HPV16 E6 variants containing amino acid substitutions in the N-terminal region of E6 were evaluated for different biological and biochemical activities in human keratinocytes, the target cells for HPV infection. Western blot analyses of primary foreskin human keratinocytes or immortalized human keratinocytes, stably transduced with the E6 variants, revealed reduced p53 and Bax levels in all E6 expressing cultures. The reduction induced by most E6 proteins was at similar levels and comparable to the reduction induced by the E6 prototype. The ability of the proteins to induce serum/calcium-differentiation resistant colonies in primary keratinocytes was more variable. Overall activities of the variants ranged between 0.24- and 2.18-fold of the E6 prototype activity. The I27R/L83V variant showed the lowest activity whereas the R8Q variant showed the highest activity. The L83V polymorphism previously associated with risk for cancer progression in some populations, showed significant activity, comparable to that of the E6 prototype, in reducing p53 and Bax levels. Furthermore, this variant showed enhancement in the ability to induce colonies resistant to serum/calcium-triggered differentiation, however, the difference from the prototype was not statistically significant. This, and augmentation of other described functions might result in differences in L83V pathogenicity.     

A novel interaction between the human papillomavirus type 16 E2 and E1^E4 proteins leads to stabilization of E2

The E4 (also called E1^E4) and E2 proteins of human papillomavirus type 16 are thought to be expressed within the same cells of a lesion, and their open reading frames overlap, suggesting that they may have a functional relationship. We have examined the effect of co-expression of these two proteins and found that each enhances the level of the other. We also identified the N-terminus of E2 as the first example of a viral protein that directly binds the HPV16 E1^E4 protein. This appears to result in the E2 becoming less soluble and promotes its relocation from the nucleus to the cytoplasm. In addition, the turnover of the E2 protein is decreased in the presence of E1^E4. All this raises the possibility that E1^E4 acts to influence E2 activity by varying the amount of available E2 in the cell.     

肛管和肛周尖锐湿疣中人乳头状瘤病毒的检测及意义

将３２例肛管和肛周尖锐湿疣进行Ａｐｇａｒ评分和凹空细胞分型，应用聚合酶链反应和免疫组化技术检测ＨＰＶ抗原和ＤＮＡ，并观察ＨＰＶ在尖锐湿疣组织中的分布状况。结果发现Ａ型１４例，Ｂ型１８例，Ａ型与高积分尖锐湿疣的关系较Ｂ型密切。ＰＣＲ和免疫组化检测阳性率分别为２５％（８／３２）和２２％（７／３２）。我们发现在尖锐湿疣组织中，不论是否是凹空细胞或凹空细胞分型如何及Ａｐｇａｒ积分高低，均有ＨＰＶ分布，但阳性率不同。这表明在正确诊断尖锐湿疣时，凹空细胞核形态、组织学改变和特殊检测三者各起作用并彼此相关。本文还探讨了浆膜型抗原发生机制。     

人乳头瘤病毒16型E5转化基因的克隆及原核表达

目的建立人乳头瘤病毒16型E5基因的无性繁殖系,为进一步研究其致癌机理作准备.方法用PCR技术从HPV16质粒DNA中扩增出E5基因序列,连接到pGEM-T载体,将阳性的重组pGEM-T用BamH Ⅰ/EcoRⅠ双酶切并回收目的片段连接到原核表达载体pGEX-2T,转化DH5α菌株.取工程菌,IPTG诱导表达,SDS-PAGE电泳鉴定.结果①经PCR、测序和双酶切鉴定,认为HPV16E5正确插入上述表达载体,建立了该转化基因的无性繁殖系.②经IPTG诱导的pGEX-2T-E5质粒表达出约42KD的融合蛋白,分析含有约16KD HPV16 E5蛋白,与预期含HPV16 E5的融合蛋白分子量相符.结论①采用PCR克隆技术,扩增HPV16 E5转化基因目的片段,将其克隆到pGEM-T载体在国内首次建立了HPV16 E5转化基因的无性繁殖子.②成功构建HPV16 E5基因的原核表达质粒,并表达出GST-E5融合表达蛋白.     

HPV16/18和HPV16E6/E7DNA在宫颈癌组织中的表达

目的检测HPV16/18和HPV16E6/E7 DNA在宫颈癌组织中的表达,探讨其在宫颈癌发病中的作用.方法应用PCR和琼脂糖凝胶电泳方法检测46例宫颈癌组织中HPV16/18和HPV16E6/E7DNA.结果 46例宫颈癌中56.5%(26/46)扩增HPV16/18 DNA,其中宫颈鳞癌25例,宫颈腺癌1例.正常对照组20例HPV16/18DNA均为阴性,与宫颈癌组相比差异有显著性(P<0.01).HPV16/18 DNA阳性拷贝对数值为4.32±2.45.HPV16E6,E7DNA分别有53.8%(14/26)、46.2%(12/26)扩增.结论 HPV16/18和HPV16E6/E7 DNA与宫颈癌的发生密切相关,是宫颈癌恶性转化的关键之一,预示着宫颈癌有较强的增殖能力和转移能力.     

The human papillomavirus type 11 E1/\E4 protein is not essential for viral genome amplification

An abundant human papillomavirus (HPV) protein E1/\E4 is expressed late in the virus life cycle in the terminally differentiated layers of epithelia. The expression of E1/\E4 usually coincides with the onset of viral DNA amplification. However, the function of E1/\E4 in viral life cycle is not completely understood. To examine the role of E1/\E4 in the virus life cycle, we introduced a single nucleotide change in the HPV-11 genome to result in a truncation of E1/\E4 protein without affecting the E2 amino acid sequence. This mutated HPV-11 genome was introduced into a human foreskin keratinocyte cell line immortalized by the catalytic subunit of human telomerase, deficient in p16(INK4a) expression, and previously shown to support the HPV-11 life cycle when grown in organotypic raft culture. We have demonstrated that E1/\E4 is dispensable for HPV-11 viral DNA amplification in the late stages of the viral life cycle.     

人乳头瘤病毒16型修饰后E6E7基因免疫原性增强

利用突变修饰后消除转化活性并保留抗原性的中国山东地方株人乳头瘤病毒16型(human papillomavirus type 16,HPVl6)E6E7融合基因(fmE6E7)，研制治疗HPVl6相关疾病的DNA疫苗。用PCR扩增fmE6E7基因后，插人真核表达质粒获得pVRl012-fmE6E7，瞬时转染Cos-7细胞，免疫荧光法检测证实其表达后，在C57BL／6小鼠后腿肌肉进行裸DNA免疫，5lCr释放法体外分析免疫鼠的细胞毒性T淋巴细胞活性Cytotoxic T lymphocyte，CTL)，间接ELISA法检测免疫鼠血清中E7特异性抗体。研究表明修饰后的中国地方株E6E7融合基因可诱导机体产生特异的抗体反应和CTL反应，与单独野生型E7基因免疫相比，E6E7融和基因可更好的活化CTT反应。表明修饰后消除转化活性的中国地方株E6E7融合基因可作为HPVl6治疗性DNA疫苗的靶基因。     

Genetic diversity of human papillomavirus type 16 E6, E7, and L1 genes in Italian women with different grades of cervical lesions

High‐risk human papillomaviruses (HPVs) are risk factors for the development of cervical cancer. HPV 16 is the most common type, being present in about 60% of cervical cancers worldwide. Previous studies have reported upon the association between HPV 16 E6 variants and increased risk of cervical intraepithelial neoplasia and invasive cervical cancer. In this study, the presence of HPV 16 polymorphisms in the E6, E7, and L1 genes was investigated in relation to the presence of high‐grade lesions. Sequencing of the E6 gene revealed the presence of nucleotide mutations resulting in 15 amino acid changes. Of these, the G134D and C136R fall within the CXXC zinger finger domain important for p53 binding. In the E7 gene, four nucleotide variations were identified with two leading to the amino acid substitutions L15V and S31R. The L1 gene showed 13 nucleotide changes leading to 11 amino acid substitutions. Among these, the R364C and N367D are located at the base of the HI‐loop of the L1 protein, considered to be the immunodominant epitope of HPV 16. No significant relationship between HPV 16 variants and high‐grade lesions was found. Phylogenetic analysis showed that all the HPV 16 variants identified belonged to the European lineage, except one which was of the Asian‐American lineage. The European‐350G variant was detected most frequently (22 of 34, 64.7%). The study provides some new data on the genetic diversity of HPV 16 which may help to understand the oncogenic potential of the virus and to improve management of patients. J. Med. Virol. 81:1627–1634, 2009. © 2009 Wiley‐Liss, Inc.     

Analysis of the roles of E6 binding to E6TP1 and nuclear localization in the human papillomavirus type 31 life cycle

The E6 oncoproteins of high-risk human papillomaviruses provide important functions not only for malignant transformation but also in the productive viral life cycle. E6 proteins have been shown to bind to a number of cellular factors, but only a limited number of analyses have investigated the effects of these interactions on the viral life cycle. In this study, we investigated the consequences of HPV 31 E6 binding to E6TP1, a putative Rap1 GAP protein. HPV 16 E6 has been shown to bind as well as induce the rapid turnover of E6TP1, and similar effects were observed with HPV 31 E6. Mutation of amino acid 128 in HPV 31 E6 was found to abrogate the ability to bind and degrade E6TP1 but did not alter binding to another alpha-helical domain protein, E6AP. When HPV 31 genomes containing mutations at amino acid 128 were transfected into human keratinocytes, the viral DNAs were not stably maintained as episomes indicating the importance of this residue for pathogenesis. Many E6 binding partners including E6TP1 are cytoplasmic proteins, but E6 has been also reported to be localized to the nucleus. We therefore investigated the importance of E6 localization to the nucleus in the viral life cycle. Using a fusion of E6 to Green Fluorescent Protein, we mapped one component of the nuclear localization sequences to residues 121 to 124 of HPV 31 E6. Mutation of these residues in the context of the HPV 31 genome abrogated the ability for episomes to be stably maintained and impaired the ability to extend the life span of cells. These studies identify two activities of HPV 31 E6 that are important for its function in the viral life cycle and for extension of cell life span.     

Prevalence of human papillomavirus types 6, 11, 16, 18, 31, and 33 in a cohort of Greek women

To study HPV prevalence and HPV types 6, 11, 16, 18, 31, and 33 distribution in cervical smears in a cohort of Greek women. One thousand six hundred thirty-six samples were cytologically evaluated and molecularly analyzed, by PCR based assay. Abnormal cytology was identified in 997 women and 75.4% of them were HPV DNA positive, while 639 had normal cytology and 24.6% were HPV DNA positive. HPV was detected in 62.9% of 256 ASCUS smears, 89.3% of 516 LSIL, 86.7% of 60 HSIL and 47.3% of 165 with cervical carcinoma. Overall, HPV 11 was the most common type (13.4%), followed by 18 (10.3%), 6 (7.2%), 16 (6.4%), 31 (3.4%) and 33 (3.4%). Multiple infections with two (11.3%) or more types, primarily 11 and 18 (4.8%), were also identified. Low-risk types 11 and 6 were common in ASCUS (36.6% and 26.4%, respectively), and high-risk types 16 and 18 in HSIL (42.3% and 30.8%, respectively) and in cancer (51.3% and 41%, respectively). Multiple infections were detected in 2.2% of normal and 31.7% of HSIL. HPV prevalence was 75.4% in abnormal and 24.6% in normal cervical smears. HPV 16 and 18 were the most common types in cancer. Single infection with type 11 and multiple infections with 11 and 18 were more frequent.     

Follow-up of antibody responses to human papillomavirus type 16 E7 in patients treated for cervical carcinoma

A synthetic peptide comprising amino acids 6-35 of HPV-16 E7 was used in an ELISA to screen sera taken from 31 cervical carcinoma patients. Sera obtained before and during treatment, and in follow-up, were tested for the presence of antibodies to this peptide. Sixteen patients with negative pretreatment serum determination remained negative during treatment and follow-up. Of the 15 patients with positive pretreatment sera, 12 showed a decrease in anti-E7 6–35 antibody level during treatment. During follow-up an increase in anti-E76–35 antibody level was observed in 6 out of 7 patients with progressive or recurrent disease, whereas all patients who remained in complete remission showed stable or further decreasing antibody levels. During the course of disease of the 15 seropositive patients, serum anti-E76–35 antibody levels were compared with serum squamous cell carcinoma antigen (SCC-Ag) profiles, a clinically useful tumor marker in the management of cervical cancer patients. Similar patterns were observed in 10 out of 15 patients. The results of this study suggest that in a subset of cervical cancer patients, anti-E76–35 antibody response against HPV-16 E7 at least partially depends on the presence of viable tumor lesions, and that to some extent the anti-E7 profile reflects the course of disease. © 1995 Wiley-Liss, inc.     

人乳头状瘤病毒18型E6E7基因诱导胎儿食管永生化上 …

目的 ＳＨＥＥ细胞系是经人乳头状瘤病毒（ＨＰＶ）１８型Ｅ６Ｅ７基因诱导的永生化上皮细胞株,已传代超过５０代。研究胎儿食管上皮永生化的细胞 ＳＨＥＥ生物学特性,包括增殖,分化和调亡。方法 细胞于１９９培养基培养,用光镜、电镜和荧光显微镜研究其生长率、形态和染色体分析;用流式细胞仪研究其细胞增殖动力学;用免疫组织化学方法研究Ｋｉ６７和角蛋白和用末端转移酶标记（ＴＵＮＥＬ）凋亡细胞。结果 细胞培养呈单导