HPV L1 C-末端保守序列短肽体液免疫学特性

目的 探讨一段位于HPV L1 C-末端、长30个氨基酸残基的保守序列的体液免疫学性质而进行此实验.方法 以此序列为基础人工合成短肽,以该短肽免疫小鼠和兔,获得抗血清,通过ELISA,Western Blot及免疫组织化学的方法,分别对含HPV6b,16及18 L1的细胞裂解物、重组蛋白或HPV阳性临床标本进行反应.结果 抗短肽抗血清能与含HPV6b,16及18 L1的细胞裂解物、重组蛋白发生针对HPV L1的反应,能使HPV6和16阳性的临床标本呈现阳性反应,而抗HPV16及抗重组HPV16 L1抗血清对此短肽的反应则较弱.结论结果表明由该保守序列短肽诱导的抗血清具有一定的型间交叉反应特征,这一特性可能对研究检测用广谱HPV L1抗体有一定的意义.该序列短肽抗血清对不同型HPV L1反应的差异性及抗血清对多型别HPV L1的反应是否具有中和性,尚需进一步的研究.     

机体对HPV L1免疫应答的研究进展

HPV L1相关的免疫应答是天然免疫和适应性免疫协同作用的结果,目前相关的研究已经渗入了免疫应答的全过程.天然免疫参与HPV L1诱导的免疫应答,但人们对它的认识仍然很有限.适应性免疫研究的进展主要体现在3方面①识别阶段.HPV的相关抗原主要由DC和LC摄取、加工、处理,经胞质溶胶、交叉提呈两种提呈途径提呈给CD8+细胞并使其致敏.②增殖分化阶段.Th1和Th2细胞都有出现,表明HPV L1不仅介导体液免疫,也介导细胞免疫.③效应阶段.L1介导产生的IgG、IgA、IgM类抗体都有其特殊性.     

A human papillomavirus type 16 vaccine by oral delivery of L1 protein

To establish an edible HPV16 vaccine, we constructed a recombinant HPV16 L1-expressing Schizosaccharomyces pombe yeast strain (HPV16L1 yeast). A preliminary study revealed that freeze-dried yeast cells could be delivered safely, and were digested in the mouse intestine. The freeze-dried HPV16 L1 yeast was administered orally as an edible vaccine, with or without the mucosal adjuvant heat-labile toxin LT (R192G), to 18 female BALB/c mice. After the third immunization, none of the mice that received the edible HPV16 vaccine showed specific antibody responses, whereas all of the positive controls that were administered intranasally with 5 μg of HPV16-virus-like particles (VLP) had serum IgG, and genital IgA and IgG that reacted with HPV16-VLP in enzyme-linked immunosorbent assays (ELISAs). When a suboptimal dose (1 μg) of HPV16-VLP was administered to all the mice, including the negative control mice, 50% of the mice that were pre-immunized with the edible HPV16 vaccine showed positive serum IgG responses, while none of the negative controls showed any response. Vaginal IgG and IgA antibodies were also elicited in 33 and 39%, respectively, of the mice that were given with the edible HPV16 vaccine and the intranasal boost. All of the antibodies reacted more strongly to intact HPV16-VLP than to denatured HPV16-L1 protein suggesting that the edible vaccine primes for antibody responses against conformation-dependent epitopes. The inclusion of adjuvant in the vaccine formulation marginally increased the genital IgA response (P = 0.06). HPV16-L1 protein in the yeast might induce tolerance in the vaccinated animals that could be recovered by intranasal boosting with a suboptimal dose of HPV-VLP. This freeze-dried yeast system may be useful as an oral delivery of HPV 16 L1 protein.     

5'-RACE法扩增抗人乳头瘤病毒16型L1蛋白单克隆抗体轻链可变区基因及序列分析

目的 获得抗人乳头瘤病毒16型(HPV16)L1蛋白单克隆抗体的轻链可变区(VL)基因并分析序列.方法 从分泌抗HPV16L1蛋白单克隆抗体的杂交瘤细胞中提取总RNA,逆转录形成cDNA,用5'-RACE策略扩增抗体轻链可变区基因,经琼脂糖凝胶电泳鉴定,并测序及进行序列分析.结果 VL基因全长336bp,编码112个氨基酸,基因测序结果符合小鼠抗体轻链可变区特征.结论 5'-RACE法成功获得了抗HPV16L1蛋白的单克隆抗体轻链可变区基因的真实序列,为基因工程抗体研究奠定了良好基础.     

人乳头瘤病毒16型晚期蛋白L1的表达及病毒样颗粒的装配

目的　在昆虫细胞中表达人乳头瘤病毒 16型 (HPV16 )哈尔滨地区分离株的晚期蛋白L1,并分离纯化由L1蛋白在细胞中自主组装成的病毒样颗粒 ,为HPV16预防性疫苗的研制奠定基础。方法　获得含有HPV16L1基因的重组杆状病毒并使目的蛋白L1在昆虫细胞中表达 ;对重组杆状病毒的扩增条件及L1蛋白的表达水平进行优化 ;电镜下观察昆虫细胞中晚期蛋白装配成病毒样颗粒的情况 ,经氯化铯密度梯度纯化病毒样颗粒 ,并经Westernblot进行验证。结果　获得了稳定表达L1蛋白的重组杆状病毒 ;以MOI值为 0 .2感染昆虫细胞可获得较高滴度的重组病毒 ,以MOI值为 10感染昆虫细胞可获得较高水平的L1蛋白表达 ;电镜下可观察到昆虫细胞核内直径为 5 5nm的病毒样颗粒 ;病毒样颗粒可通过氯化铯密度梯度离心获得。结论　获得人乳头瘤病毒哈尔滨地区分离株L1蛋白可在昆虫细胞中自主装配的病毒样颗粒并成功分离纯化。     

人乳头瘤病毒58型L1壳蛋白在原核细胞中的高效表达及抗体制备

目的 人乳头瘤病毒58型（HPV58）是重要的高度致瘤性病毒之一。用原核细胞表达HPV58L1主要壳蛋白（McP）,并制备相应抗体血清,为基因工程疫苗研制打下基础。方法 用聚合酶链反应(PCR）扩增HPV58L1完整编码区基因,并克隆、测序。构建原核表达载体pRSETB58L1,表达的L1蛋白经SDS－PAGE纯化,免疫BALB／c小鼠。结果 在原核细胞中表达了HPV58L1壳蛋白,该壳蛋白的相对分子质量为60000,此蛋白与HPV16L1抗有交叉反应。获得抗HPV58L1壳蛋白特异性抗体,抗体滴度为1：80,并用该抗体屯昆虫细胞中表达的HPV58L1壳蛋白。结论 HPV58壳蛋白在原核细胞中获得的有效表达,纯化免疫小鼠后能产生抗HPV58L1特异性抗体,此抗体可用于鉴定真核细胞表达的HPV58L1壳蛋白。     

Sourcing of the WHO human papillomavirus type 18 international standards for HPV antibody levels

BackgroundHPV serology is important for studies of vaccine immunogenicity, but can not be performed in a comparable manner without international standardisation.ObjectivesTo find suitable candidate sera from naturally infected persons for use as International Standards (IS) for antibodies to high-risk HPVs, with priority for HPV-18.Study design946 healthy Thai women (median age 44, range 18–83) and 61 cervical cancer patients were screened using an HPV pseudovirion-Luminex assay to detect antibodies to genital (HPV-6,-11,-16,-18,-31,-33,-45,-52,-58,-68) and non-genital HPV types (HPV-5,-15,-32,-38 and -76). Suitable candidate sera should ideally be mono-specific (have reactivity against only one genital HPV) and have high antibody levels that are stable over time.ResultsSeroprevalences of HPV-16,-31,-52 and -58 were at least twice as high among cancer patients compared to healthy individuals. Thirteen healthy women who met the IS inclusion criteria in initial testing also consented to blood-bag donations. Donations from 2 women with high HPV-18 Ab titers were pooled to the HPV-18 candidate IS, later established as the WHO official IS for HPV antibodies. Sera that could potentially be used as candidate IS for other oncogenic HPVs have also been identified.ConclusionsIn the Thai population, seroepidemiology implicated HPV types HPV-16,-31,-52 and -58 as particularly associated with cervical cancer. A well characterized cohort study has allowed sourcing of materials for an IS for HPV-18 antibodies and could conceivably be used for IS for other HPV types as well.     

Mutational analysis of human papillomavirus type 16 major capsid protein L1: the cysteines affecting the intermolecular bonding and structure of L1-capsids

Human papillomavirus 16 major capsid protein L1 (composed of 505 amino acids (aa) including 12 cysteines) assembles by itself into virion-like icosahedral particles (L1-capsids), each of which is dissociated into 72 pentameric capsomeres when intermolecular disulfide bonds are disrupted. To identify the cysteines affecting the bonding and the structural integrity of the L1-capsids, we constructed a series of L1 mutants with substitution of serine for cysteine, which were expressed from recombinant baculoviruses in the insect Sf9 cells. From infected cells, the self-assembled L1-capsid fractions were purified by CsCl-equilibrium centrifugation and examined for velocity sedimentation profiles, for the presence of intermolecular bonding by SDS-PAGE with or without a reducing agent, for morphology under an electron microscope, and for susceptibility to trypsin digestion. Mutants C175S (C at aa 175 was replaced with S) and C185S were sedimented in sucrose-density gradients slightly slower than the wild type (WT) capsids, and mutant C428S stayed near the top as WT-capsomeres did. In the nonreducing SDS gel, where WT-capsids were separated into two bands of L1-trimers and L1-dimers, the C175S-trimer band was not detected, the C185S-dimer band was much less dense, and the C428S-trimer and C428S-dimer bands were not detected. Thus, it seems likely that C175, C185, and C428 are involved in L1 trimerization, in L1 dimerization, and in both, respectively. Morphologically, the C175S, C185S, and C428S fractions appeared to consist mostly of heterogeneous rod-shaped tubules, of smaller spherical particles, and of only capsomeres, respectively, whereas C102S, C229S, and C379S resembled WT. The C161S, C175S, C185S, C229S, C379S, and C428S capsids were more sensitive to degradation caused by trypsin than WT. The results indicate that C175, C185, and C428 are required for the normal assembly of L1-capsids through trimerization and dimerization of L1 bound by the intercapsomeric disulfide bonds between cysteines, and that C161, C229, and C379 are necessary for the integrity of L1-capsids probably through intramolecular bonding.     

A novel human papillomavirus type 6 neutralizing domain comprising two discrete regions of the major capsid protein L1.

We have mapped the binding sites on human papillomavirus (HPV) type 6 for three HPV 6-specific neutralizing monoclonal antibodies (mAbs). The critical binding residues were first identified by making HPV 11-like amino acid substitutions in the HPV 6 major capsid protein L1 and assaying the resulting virus-like particles (VLPs) for reactivity with the mAbs. To confirm the relevance of these residues for mAb binding, we demonstrated that HPV 6 type-specificity could be transferred to HPV 11 VLPs by making the appropriate HPV 6-like amino acid substitutions in the HPV 11 L1. Two binding regions were found. For one mAb, all critical residues are centered at residue 53, while for the other two mAbs, type-specific binding also requires a second site located more than 100 residues distal to the first. Both binding sites coincide with regions of L1 where the sequences of the closely related HPV 6 and 11 diverge. These regions are where the L1 sequences are the least well conserved among all HPV types and they have been implicated in type-specific binding for other HPV types. This suggests that clusters of diverged residues, surrounded by conserved L1 sequences, are presented on the surface of assembled particles and are responsible for eliciting critical humoral immune responses to the virus.     

Identification of the nuclear localization signal of human papillomavirus type 16 L1 protein.

Human papillomavirus type 16(HPV16) L1 and L2 capsid proteins can be detected only in the nucleus of infected cells. For other nuclear proteins, specific sequences of basic amino acids(aa) termed nuclear localization signals (NLS) direct the protein from the cytoplasm to the nucleus. We used a series of deletion and substitution mutations of the HPV16 L1 protein, produced by recombinant vaccinia virus (rVV), to identify NLS within HPV16 L1 and showed that HPV16 L1 contains two NLS sequences, each containing basic aa clusters. One NLS consisted of 6 basic amino acids (KRKKRK from aa 525 to 530) at the carboxy terminal end of L1. The other NLS contained 2 basic aa clusters(KRK from aa 510 to 512 and KR at aa 525, 526) separated by 12 amino acids. Mutations in either NLS did not alter nuclear localization of L1 when the other remained intact, but mutations to both prevented nuclear localization of L1. The L1 NLS could be overridden by introduction of a membrane binding sequence at the amino terminal end of the protein. A databases search showed that all sequenced papillomaviruses are predicted to have L1 and L2 capsid proteins with sequences of basic amino acids homologous with one or both NLS of HPV16 L1.     

型特异性、构象依赖性HPV16 L1单克隆抗体的制备与鉴定

目的:研制具有型特异性和构象依赖性的人乳头瘤病毒16主衣壳L1蛋白(HPV16 L1)单克隆抗体(mAb).方法:利用昆虫-杆状病毒系统表达有生物活性的HPV16 L1蛋白.非变性条件下纯化HPV16 L1蛋白,免疫6周龄雌性BALB/c小鼠.末次加强免疫后取其脾细胞与骨髓瘤Sp2/0细胞融合,应用间接ELISA筛选阳性克隆.非变性Western blot鉴定mAb的型特异性和构象依赖性,细胞免疫组化确定抗体的型特异性.间接ELISA法测定杂交瘤分泌上清及腹水中抗体效价.mAb亚类试剂盒鉴定mAb亚类.结果:获得1株稳定分泌具有型特异性和构象依赖性的HPV16 L1抗体的杂交瘤细胞株,命名为2E3.2E3杂交瘤细胞株细胞培养上清中抗体效价为1:800;小鼠腹水中抗体效价为1:12 800.亚类鉴定结果为IgG1κ.Western blot及细胞免疫组化分析结果显示,2E3 mAb具有型特异性和构象依赖性,只与非变性的HPV16 L1蛋白发生反应,不与HPV18L1、HPV58L1、HPV11L1产生交叉反应.结论:成功制备了型特异性HPV16 L1 mAb,为进一步研究HPV16 L1的抗原表位奠定了基础.     

人乳头瘤病毒(HPV)L2肽免疫小鼠诱导的抗体水平与保护作用的关系研究

目的 检测HPV-58 L2 11～200 AA肽在动物体内对HPV的保护效果,并分析疫苗诱导的抗体滴度或中和抗体滴度与疫苗保护作用之间的对应关系.方法 利用大肠杆菌表达HPV-58L2 11～200 AA肽,纯化目的 蛋白并与铝佐剂吸附后免疫小鼠,利用小鼠HPV-58假病毒感染模型检测不同剂量的免疫原对小鼠的保护作用.通过ELISA和假病毒中和抗体检测方法 检测免疫血清中的总抗体水平和中和抗体水平,分析具有保护作用的抗体或中和抗体滴度.结果 当蛋白免疫剂量为8μg时,能够完全保护小鼠不受HPV假病毒的感染.小鼠免疫血清中的中和抗体水平较低,利用已建立的假病毒中和试验方法 检测不到血清中的中和抗体.而利用ELISA检测血清中的总抗体水平结果 显示,免疫血清中的总抗体水平与疫苗的保护效果之间存在对应关系,当抗体滴度大于等于1:25 000时,小鼠体内检测不到荧光信号,能够保护机体不受假病毒的感染.结论 HPV-58 L2 11～200 AA肽能够保护小鼠不受假病毒的感染,L2 11～200 AA肽具有较好的疫苗发展前景,其引发的总抗体水平可以作为评价保护效果的间接指标.     

Nucleotide sequence of human papillomavirus (HPV) type 41: an unusual HPV type without a typical E2 binding site consensus sequence.

The complete nucleotide sequence of human papillomavirus type 41 (HPV-41) has been determined. HPV-41 was originally isolated from a facial wart, but its DNA has subsequently been detected in some skin carcinomas and premalignant keratoses (Grimmel et al., Int. J. Cancer, 1988, 41, 5-9; de Villiers, Grimmel and Neumann, unpublished results). The analysis of the cloned HPV-41 nucleic acid reveals that its genome organisation is characteristic as for other papillomavirus types. Yet, the analysis indicates at the same time that this virus is most distantly related to all other types of human-pathogenic papillomaviruses sequenced thus far and appears to identify HPV-41 as the first member of a new subgroup of HPV. The overall nucleotide homology to other sequenced HPV types is below 50%. The closest other HPV type is represented by HPV-18, sharing 49% identical nucleotides. The typical E2 binding sequence ACCN6GGT, found in all papillomaviruses analyzed to date, does not occur in the URR of the HPV-41 genome. Modified E2 binding sequences, as described for BPV 1 (Li et al., Genes Dev. 1989, 3, 510-526), are located in the domain proximal to the E6 ORF. These are ACCN6GTT, AACN6GGT and the two perfect palindromic sequences AACGAATTCGTT.     

Regulation of human papillomavirus type 1 replication by the viral E2 protein

The E1 and E2 proteins encoded by papillomaviruses are required for viral replication. Earlier studies have shown that the viral E2 protein plays an important role in replication by targeting the E1 helicase to the origin of replication (ori). We have previously shown that the E1 protein of human papillomavirus (HPV) type 1 is sufficient for the in vivo replication of ori plasmids, although the E2 protein stimulates replication. In this study, we have further analyzed the role of the E2 protein in HPV-1 replication. The optimal ori of HPV-1 contains one putative E1 binding site (E1BS) and two putative E2 binding sites, E2BS-3 and E2BS-4. Plasmid pori171, containing the optimal ori, replicates to much higher levels than plasmid pori312, which includes an additional upstream E2 binding site, E2BS-2, located 75 nucleotides upstream of E2BS-3. To study the possible role of E2BS-2 and other upstream sequences in E2-dependent downregulation of replication, transient replication analysis was done in the presence of increasing levels of the E2 protein. Interestingly, inhibition of pori312 replication was more severe at higher levels of E2, suggesting that this protein may also negatively regulate HPV-1 replication. Deletion of sequences from pori312 containing an additional putative E2BS, E2BS-2A, relieved the repression of replication to a significant extent, while replacement of E2BS-2 with a different sequence of the same length had a modest effect. These results suggest that E2BS-2A plays a major and E2BS-2 a minor role in the negative regulation of HPV-1 replication at high E2 levels. Electrophoretic mobility-shift assays showed that the purified E2 protein bound with high affinity to E2BS-3 and weakly to the other putative E2BSs located within the viral long control region. EMSA using various ori fragments showed the formation of multiple E2-DNA complexes which likely represent binding of E2 to multiple E2BSs present within the HPV-1 ori. Our data are consistent with the assembly of ori-protein complexes at high E2 levels that are impaired for replication and further suggest that E2 may regulate HPV-1 replication by a mechanism involving interaction between the E2 protein bound to E2BSs at a distance.     

鲍温氏病组织人乳头瘤病毒16型结构基因L1的克隆及其序列分析

本研究采用ＰＣＲ法从中国妇女鲍温氏病组织标本扩增获得了宫颈癌密切相关的人乳头瘤病毒１６型（ＨＰＶ１６）的晚期基因Ｌ１,并装入测序载体测序分析了其ＤＮＡ的序列,与标准型进行了比较,发现有若干变异,此研究对序列及变异意义进行了分析和讨论,为今后Ｌ１基因分子流行病学调查,Ｌ１蛋白的结构与功能研究、疫苗研制以及ＨＰＶ相关的基础性研究提供了有用的资料,同时在国内外首次报道了鲍温氏病组织中ＨＰＶ１６Ｌ１的序列     

Cloning and expression of the L1 major capsid protein of the human papillomavirus 18 in murine cells

Human papillomavirus (HPV) type 18 is strongly associated with the development of cervical cancer. Studies of a model system with animal papillomaviruses have demonstrated the importance of neutralizing antibodies in preventing papillomavirus-associated disease. The immune response to HPV is poorly understood, and there are non- standardized serological assays to identify HPV infections. In our study, the assessment of antibody responses against HPVs (previously hampered by the lack of viral source) was enabled by the expression of the L1 major capsid viral protein type 18 (HPV18) into L929 murine cells using the pTARGET mammalian expression vector system (MEVS). The cloning was validated by PCR with specific primers for the L1 gene, as well as by enzyme restriction and in situ hybridization. The evidence for the viral cloned gene expression was acquired by RT-PCR. Presence and antigenic properties of the recombinant L1 protein were shown using it as antigen in an indirect enzyme linked immunosorbent assay (ELISA) system. Significantly higher reactivity was noted when the sera samples were from persons infected with HPV18 as compared with the non-infected individuals but a moderately different reactivity was observed when the sera from patients infected with other HPV genotypes were tested. The results showed that the murine transfected cells could be used as antigen in order to detect the presence of the specific antibodies in HPV infected persons.     

HPV antibody detection by ELISA with capsid protein L1 fused to glutathione S-transferase

An alternative enzyme linked immunosorbent assay (ELISA) system was developed to analyze antibodies to human papillomavirus capsid antigens. The assay uses glutathione crosslinked to casein to capture the major capsid protein L1 from human papillomavirus (HPV) types 6b, 16 and 18 fused to glutathione S-transferase (GST) as antigen. The method allows efficient one-step purification of L1 fusion protein from crude bacterial lysates on ELISA plates coated with glutathione casein. The GST-L1 capture ELISA detected HPV 16 antibodies with high type specificity. Comparison with the current "gold-standard" for L1-serology that uses virus-like particles (VLP) as antigen demonstrated similar assay sensitivity. Pairwise comparison of the absorbance values of 105 human sera obtained in the two ELISA formats for HPV 16 showed a R(2) value of linear regression of 0.68. Conformity of the two ELISAs in classification of sera as HPV 16 L1 antibody-positive or -negative was verified with Cohen's kappa test, yielding a value of 0.62. These data indicate that the GST-L1 capture ELISA is similar in performance to the VLP ELISA. The ease of antigen production and purification in the GST-based ELISA will be advantageous to screen large sample numbers in vaccine trials or epidemiological studies examining immune responses to many HPV types in parallel.     

Purification and immunogenicity study of human papillomavirus type 16 L1 protein in Saccharomyces cerevisiae

Human papillomavirus 16 virus-like particle (HPV16 VLP) vaccines expressed in Saccharomyces cerevisiae are under Phase III trial and are expected to be on the market in the near future. We have established a convenient and economical system for the prophylactic study of vaccines derived from HPV16 VLPs, and neutralization tests to standardize HPV serological methodology as a measure of validation. To purify HPV16 VLPs, yeast cells expressing HPV16 L1 protein were cultured and purified on a small scale by ultracentrifugation and size-exclusion and cation-exchange chromatography using open columns. The highly purified HPV16 L1 protein was identified by SDS-PAGE and Western blotting, and electron microscopic analysis confirmed that they self-assembled into VLPs. To test the efficacy of the purified VLPs as a vaccine and their ability to induce humoral immunity, we performed ELISA assays and observed a significant increase in the titer of anti-HPV16 VLPs antibodies in the sera of immunized mice. High anti-HPV16 neutralizing titers were found in the sera of vaccinated mice, as measured by a SEAP-based pseudovirus neutralization assay. These results would be useful in the evaluation of the immunogenicity of HPV vaccine candidates, and provide an international reference standard for HPV serological methods.