Characterization of capsid-modified adenovirus vectors containing heterologous peptides in the fiber knob, protein IX, or hexon

Adenovirus (Ad) vectors are widely used in gene therapy and in vitro/in vivo gene transfer because of their high transduction efficiency. However, Ad vector application in the gene therapy field is limited by poor transduction into cells not expressing the primary receptor, coxsackievirus and adenovirus receptor. To overcome this problem, several types of capsid-modified Ad vectors have been developed. The HI loop or C-terminus of the fiber knob, the C-terminus of the protein IX (pIX) and the hypervariable region 5 of the hexon are promising candidate locations for displaying foreign peptide sequences. In the present study, we constructed Ad vectors in which each of the above region was modified by a simple in vitro ligation-based method, and examined the characterization of each Ad vector containing the FLAG tag (DYKDDDDK) or RGD (CDCRGDCFC) peptide. Enzyme-linked immunosorbent assay examining the surface expression of foreign peptides on the virus suggested that foreign peptides are exposed on virion surfaces in all types vectors and that the hexon was the most efficiently reacted, reflecting the copy number of the modification. However, in the case of the transduction efficiency of Ad vectors containing the RGD peptides, the modification of pIX and the hexon showed no effect. The modification of the HI loop of the fiber knob was the most efficient, followed by the modification of the C-terminus region of the fiber knob. These comparative analyses, together with a simple construction method for each modified Ad vector, could provide basic information for the generation of capsid-modified Ad vectors.     

A simplified system for constructing recombinant adenoviral vectors containing heterologous peptides in the HI loop of their fiber knob.

The use of recombinant adenovirus (Ad) vectors containing genetically modified capsid proteins is an attractive strategy for achieving targeted gene transfer. The HI loop of the fiber knob is a promising candidate location for the incorporation of foreign ligands for achieving this goal. However, the method of constructing an Ad vector containing a foreign ligand in the HI loop of the fiber knob has proved difficult. In this study, we developed a simple system to construct fiber-modified vectors. To do this, a vector plasmid containing a complete E1/E3-deleted Ad type 5 genome and a unique Csp45I and/or ClaI site between positions 32679 and 32680 of the Ad genome (residues threonine-546 and proline-547 of the fiber protein) was constructed. Oligonucleotides corresponding to the Arg-Gly-Asp (RGD) or Asn-Gly-Arg (NGR)-containing peptide motif (as a model) and containing a Csp45I and/or ClaI recognition site, were ligated into the Csp45I and/or ClaI-digested plasmid. The foreign transgene expression cassette was inserted into the E1 deletion site of the vector plasmid and the fiber-mutant Ad vector was produced by transfection of the PacI-digested plasmid into 293 cells. The virus containing the RGD or NGR peptide on the fiber knob was able to infect human glioma cells, which do not express coxsackievirus and adenovirus receptor (CAR), one of the Ad virus receptors, about 100-1000 times more efficient than the virus containing wild-type fiber. This suggested that the mutant virus mediated CAR-independent cell entry pathway. The simplicity of this method allows not only for easy construction of fiber-mutant Ad vectors, but also for screening of the peptides that target the vector to the desired cells and tissues.     

Oncolytic adenovirus modified with somatostatin motifs for selective infection of neuroendocrine tumor cells

We have previously described the oncolytic adenovirus, Ad(CgA-E1A-miR122), herein denoted Ad5(CgA-E1A-miR122) that selectively replicates in and kills neuroendocrine cells, including freshly isolated midgut carcinoid cells from liver metastases. Ad5(CgA-E1A-miR122) is based on human adenovirus serotype 5 (Ad5) and infects target cells by binding to the coxsackie-adenovirus receptor (CAR) and integrins on the cell surface. Some neuroendocrine tumor (NET) and neuroblastoma cells express low levels of CAR and are therefore poorly transduced by Ad5. However, they often express high levels of somatostatin receptors (SSTRs). Therefore, we introduced cyclic peptides, which contain four amino acids (FWKT) and mimic the binding site for SSTRs in the virus fiber knob. We show that FWKT-modified Ad5 binds to SSTR? on NET cells and transduces midgut carcinoid cells from liver metastases about 3-4 times better than non-modified Ad5. Moreover, FWKT-modified Ad5 overcomes neutralization in an ex vivo human blood loop model to greater extent than Ad5, indicating that fiber knob modification may prolong the systemic circulation time. We conclude that modification of adenovirus with the FWKT motif may be beneficial for NET therapy.     

Modified adenoviral vectors ablated for coxsackievirus-adenovirus receptor, alphav integrin, and heparan sulfate binding reduce in vivo tissue transduction and toxicity

Coxsackievirus and adenovirus receptor (CAR), alphav integrins, and heparan sulfate glycosaminoglycans (HSGs) are the tropism determinants of adenoviral (Ad) vectors in vivo. For the development of a targeted Ad vector, its broad tropism needs to be blocked (or reduced). We have previously developed Ad vectors with ablation of CAR, alphav integrin, and HSG binding by mutation of the FG loop in the fiber knob (deletion of T489, A490, Y491, and T492 of the fiber protein), deletion of the RGD motif of the penton base, and substitution of the fiber shaft domain for that derived from Ad type 35, respectively, and have shown that this triple-mutant Ad vector [Ad/deltaF(FG)deltaP-S35-L2] exhibits significantly lower transduction in mouse liver compared with the conventional Ad vector [Koizumi, N., Mizuguchi, H., Sakurai, F., Yamaguchi, T., Watanabe, Y., and Hayakawa, T. (2003). J. Virol. 77, 13062-13072]. In the present study, we optimized the fiber knob mutation for further reduced in vivo transduction and examined toxicity of the modified Ad vectors. Ad/deltaF(AB)deltaPS35- L2, a triple-mutant Ad vector containing a mutation of the AB loop in the fiber knob (R412S, A415G, E416G, and K417G), mediated approximately 15,000- and 500-fold lower mouse liver transduction by intravenous and intraperitoneal administration, respectively, than the conventional Ad vector, and mediated 10- fold lower mouse liver transduction than did Ad/deltaF(FG)deltaP-S35-L2. Ad/deltaF(AB)deltaP-S35-L2 also exhibited lower transduction of other organs compared with Ad/deltaF(FG)deltaP-S35-L2 and the conventional Ad vector. Levels of both liver serum enzymes (aspartate transferase [AST] and alanine transferase (ALT)] and interleukin (IL)-6 in mouse serum after intravenous administration of Ad/deltaF(AB)deltaP-S35-L2 were similar to those in the nontreatment mouse serum, whereas the conventional Ad vector led to high levels of AST, ALT, and IL-6. We therefore succeeded in further improving the mutant Ad vector, abolishing both viral natural tropism and toxicity. This new Ad vector appears to be a fundamental vector for targeted gene delivery.     

Influence of adenoviral fiber mutations on viral encapsidation, infectivity and in vivo tropism

Targeting of adenovirus (Ad)-encoded therapeutic genes to specific cell types has become a major goal in gene therapy. Redirecting the specificity of infection requires the abrogation of the natural interaction between the viral fiber and its cellular receptors (CAR) and the simultaneous introduction of a new binding specificity into the viral capsid. To abrogate the natural affinity of the fiber, we have mutated residues presumed to be directly or indirectly involved in CAR-binding in the knob domain of the fiber protein. These residues are located in the AB loop (Ser408) and in the DG loop (Tyr491, Ala494, Ala503). The mutations Ser408Glu, Tyr491Asp, Ala494Asp and Ala503Asp did not prevent the incorporation of trimeric fibers in the viral capsid but led to loss of CAR binding in vitro. Infectivity of the mutant viruses could be restored in vitro by introducing a ligand at the C-terminal end of the knob, confirming that the reduced infectivity of the fiber-modified virus was due to an impaired interaction of the viral particle with the CAR receptor. However, after systemic delivery, the in vivo biodistribution of impaired CAR-binding viruses without addition of a specific ligand was not altered when compared with wild-type Ad.     

Fiber shaft extension in combination with HI loop ligands augments infectivity for CAR-negative tumor targets but does not enhance hepatotropism in vivo

Recent studies demonstrate that the fiber shaft length, which ranges from six beta-repeats to 23 beta-repeats in human adenoviruses (Ads), influences viral tropism. We have previously shown that artificial extension of the shaft length inhibits infectivity in CAR (coxsackievirus and Ad receptor)-positive cell lines, but does not affect infectivity in a CAR-independent, integrin-dependent cell entry pathway. On the basis of these findings, we hypothesized that Ad vectors with shaft extension might display lower infectivity in liver, which expresses high levels of CAR. We also postulated that infectivity of Ad vectors with shaft extension in CAR-negative tumors could be increased by exploiting a CAR-independent cell entry by incorporation of an RGD4C motif into the fiber knob HI-loop. We thus compared gene transfer efficiencies of our Ad serotype 5 (Ad5) capsid-based 'longer-shafted' Ad vector with or without an RGD4C motif in the HI-loop of the fiber knob (Ad5long and Ad5RGDlong, 32 beta-repeats) to wild-type Ad vector (Ad5, 22 beta-repeats) in vitro and in vivo. In this study, Ad5long showed similar infectivity in CAR-negative tumors (69.7%, P = 0.098), but significantly reduced infectivity in CAR-positive tumors (19.1%, P = 0.000038) and in liver (12.5%, P = 0.0047) compared with Ad5. On the other hand, Ad5RGDlong demonstrated similar infectivity in CAR-positive tumors (70.5%, P = 0.012) and in liver (83.4%, P = 0.51), but significantly increased infectivity in CAR-negative tumors (327%, P = 0.0000042) compared with Ad5. Importantly, Ad5RGDlong demonstrated an augmented gene transfer capacity for CAR negative tumors, but no enhanced hepatotropism in vivo. We suggest that Ad vectors with artificial fiber shaft extension in combination with HI loop ligands may be useful for gene therapy applications.     

CAR- or alphav integrin-binding ablated adenovirus vectors,but not fiber-modified vectors containing RGD peptide,do not change the systemic gene transfer properties in mice

Targeted gene delivery to the tissue of interest by recombinant adenovirus (Ad) vectors is limited by the relatively broad expression of the primary receptor, the coxsackievirus and adenovirus receptor (CAR), and the secondary receptor, alphav integrin. This problem could be overcome by mutating the fiber and penton base, which bind with CAR and alphav integrin, respectively. In this study, we constructed CAR-binding ablated Ad vectors and alphav integrin-binding ablated Ad vectors by mutation in the FG loop of fiber knob and in the RGD motif of penton base, respectively, and compared the gene transfer properties of their vectors into various types of cultured cells and mice with conventional Ad vectors. We also generated Ad vectors containing RGD peptide in the HI loop of the fiber knob. CAR-binding ablated Ad vectors mediated about 1% of gene transfer activity into CAR-positive cultured cells, compared with conventional Ad vectors, while alphav integrin-binding ablated Ad vectors maintained at least 76% of gene transfer activity into cultured CAR-positive cells. Inclusion of the RGD peptide into the HI loop of the fiber knob of CAR-binding ablated Ad vectors restored gene transfer activity in vitro. On the other hand, systemically administered CAR-binding ablated Ad vectors, as well as alphav integrin-binding ablated Ad vectors mediated similar levels of gene transfer into mouse liver with the conventional Ad vectors. These results suggest that continued interaction of either the fiber with CAR or the penton base with alphav integrin offers an effective route of virus entry into mouse liver in vivo. Inhibition of the interaction of both the fiber with CAR and the penton base with alphav integrin is likely to be crucial to the development of targeted Ad vectors.     

The alphavbeta5 integrin of hematopoietic and nonhematopoietic cells is a transduction receptor of RGD-4C fiber-modified adenoviruses

Epithelial and endothelial cells expressing the primary Coxsackie virus B adenovirus (Ad) receptor (CAR) and integrin coreceptors are natural targets of human Ad infections. The fiber knob of species A, C, D, E and F Ad serotypes binds CAR by mimicking the CAR-homodimer interface, and the penton base containing arginine-glycine-aspartate (RGD) motifs binds with low affinity to alphav integrins inducing cell activation. Here, we generated seven different genetically modified Ad vectors with RGD sequences inserted into the HI loop of fiber knob. All mutants bound and infected CAR and alphav integrin-positive epithelial cells with equal efficiencies. However, the Ads containing two additional cysteines, both N and C terminals of the RGD sequence (RGD-4C), were uniquely capable of transducing CAR-less hematopoietic and nonhematopoietic human tumor cell lines and primary melanoma cells. Both binding and transduction of RGD-4C Ad were blocked by soluble RGD peptides. Flow cytometry of cell surface integrins and virus binding to CAR-less cells in the presence of function-blocking anti-integrin antibodies indicated that the alphavbeta5 integrin, but not alphavbeta3, alphaIIbbeta3 or beta1,alpha5 or alpha6-containing integrins served as a functional transduction receptor of the RGD-4C Ads. However, in cells with low levels of alphavbeta5 integrin, the function-blocking anti-alphavbeta5 antibodies were not effective, unlike soluble RGD peptides. Collectively, our data demonstrate that the alphavbeta5 integrin is a functional transduction receptor of RGD-4C Ads in the absence of CAR, and that additional RGD receptors are targets of these viruses. The RGD-4C vectors further extend the tropism of Ads towards potential human therapies.     

Fiber-modified adenovirus vectors containing the TAT peptide derived from HIV-1 in the fiber knob have efficient gene transfer activity

The interaction between viral capsid proteins and specific molecules exposed on the plasma membrane of the cells is involved in the viral tropism. A human adenovirus (Ad) belonging to subgroups A, C, D, E and F infects cells via the interaction between the fiber knob and the primary receptor, the coxsackievirus and adenovirus receptor (CAR). Conventional human adenovirus type 5 (hAd5) vectors show efficient transduction in CAR-positive cells; in contrast, hAd5 vector application is limited by poor transduction into cells lacking CAR expression. In the present study, to broaden the tropism of hAd5 vectors, we generated hAd5 vectors containing the TAT peptide, which is a protein transduction domain derived from human immunodeficiency virus, in the HI loop of the fiber knob (Ad-TAT(HI)-L2) or the C-terminus of the fiber knob (Ad-TAT(C)-L2). In CAR-negative adherent cells, Ad-TAT(HI)-L2 and Ad-TAT(C)-L2 showed approximately 50- to 500-fold higher gene expression than the conventional hAd5 vector (Ad-L2). Ad-TAT(HI)-L2 was also more efficient than Ad-L2 in blood cell lines and in two types of primary cultured human vascular smooth muscle cells, which are almost refractory to Ad-L2. Furthermore, Ad-TAT(HI)-L2 was more efficient than other types of fiber-modified Ad vectors, which harbor an RGD (Arg-Gly-Asp) or a poly-lysine (KKKKKKK;K7) peptide in the HI loop or the C-terminus of the fiber knob, respectively. Ad-TAT(HI)-L2 efficiently transduced the organs in levels and patterns that were roughly similar to those of Ad-L2 after being systemically injected into mice. To the best of our knowledge, this study is the first report showing that hAd5 vectors containing the TAT peptide in the fiber knob could efficiently transduce cells independently of CAR. These Ad vectors should be useful for gene functional analysis and gene therapy.     

Efficient regulation of gene expression using self-contained fiber-modified adenovirus vectors containing the tet-off system.

Previously, we developed single adenovirus (Ad) vectors that contained the gene of interest in the E1 deletion region and the transactivator gene for the tetracycline-controllable expression system in the E3 deletion region. In the present study, we improved the Ad vector-mediated tetracycline-controllable expression system by the fiber modification of Ad. We developed fiber-modified Ad vectors containing the tet-off system, which are effective in overcoming the limitations of conventional Ad vectors, specifically their inefficient gene transfer into cells lacking the primary receptor, the coxsackievirus and adenovirus receptor (CAR). Ad vectors containing the tet-off system with an Arg-Gly-Asp (RGD) peptide in the HI loop of the fiber knob or the Ad type 35 fiber greatly improved transduction efficiency (more than 1-2-log orders) into the cells lacking CAR expression but expressing alphav integrin or CD46, respectively. They exhibited vastly higher regulation of gene expression by doxycycline. The combination of fiber-modified Ad vectors and the tetracycline-controllable expression system should offer a powerful tool for gene therapy and gene transfer experiment.     

Adenovirus stripping: a versatile method to generate adenovirus vectors with new cell target specificity

We developed a new type of adenovirus type 5 (Ad5)-derived vector with genetically modified fiber proteins whose knob domains could be stripped off due to the insertion of a single Factor Xa cleavage site in the fiber shaft, between a cellular ligand and the knob domain. This Ad vector did not require a specific cell line for propagation and could be grown in HEK-293 cells. Stripping off the knob domains removed the endogenous cell-binding moiety of Ad but retained the new cell ligand for retargeting purposes. As experimental models for cell ligands, we used two peptides with different sequence complexities: (i) the integrin-binding tripeptide RGD and (ii) a 58-residue oligopeptide termed affibody (Zwt). Zwt binds specifically to the human IgG1 Fc domain or to its Fc3(1) homolog. The modified fibers were efficiently encapsidated into virions, and the Factor Xa sites were fully accessible to proteolysis. In vitro binding assays using recombinant Fc3(1) protein and Ad5-mediated gene transduction of Fc3(1)-expressing cells demonstrated that the proteolytically deknobbed Ad5-Zwt vector was functional and specific for receptor targeting.     

Genetic replacement of the adenovirus shaft fiber reduces liver tropism in ovarian cancer gene therapy

Approaches to alter the native tropism of adenoviruses (Ads) are beneficial to increase their efficacy and safety profile. Liver tropism is important with regard to potential clinical toxicity in humans. Ad5/3 chimeras in which the Ad5 knob is substituted by the Ad3 knob, such as Ad5/3luc1, have been recently shown to increase infectivity of ovarian cancer cell lines and primary tumor cells, which express low levels of the coxsackie-adenovirus receptor (CAR), without increasing infectivity of liver cells. A novel strategy to address the problem of liver uptake and improve the tumor/liver ratio is genetic replacement of the Ad fiber shaft. Ad5.Ad3.SH.luc1 is an Ad5-based vector that contains the fiber shaft from Ad serotype 3 but the fiber knob from Ad serotype 5. To compare tumor/liver of Ad5.Ad3.SH.luc1 and Ad5/3luc1 in vivo, we created three different tumor and treatment models of ovarian cancer in mice, simulating intraperitoneal and intravenous administration of tumors. Ad5.Ad3.SH.luc1 displayed the lowest liver tropism of all viruses in all models tested. Intravenous administration of all viruses resulted in higher tumor transduction rates compared to intraperitoneal administration. Genetic shortening of the Ad5 fiber shaft significantly increases relative tumor/liver gene transfer. This could improve the effective tumor dose and reduce side effects, thereby increasing the bioavailability of therapeutic agents.     

Targeting of high-capacity adenoviral vectors

High-capacity adenoviral (HC-Ad) vectors contain only the noncoding termini of the viral genome, can deliver large DNA fragments of up to 36 kb into target cells, and feature reduced toxicity and prolonged transgene expression in vivo. To enhance the potential of HC-Ad vectors to transduce specific cell types, we constructed a versatile infectious new helper virus plasmid that can be used readily to introduce peptide ligands into the HI loop of the fiber knob domain of Ad5-based HC-Ad vectors. Helper viruses with a 6x-His epitope or Arg-Gly-Asp (RGD) peptide insertion retained the full infectivity of the wild-type helper virus. The RGD-modified helper virus was used for production of a capsid-modified HC-Ad vector expressing beta-galactosidase. The RGD HC-Ad vector transduced the ovarian carcinoma cell lines SK-OV-3 and OVCAR-3 with 4- to 20-fold higher efficiency, compared to unmodified vectors. Transduction of both primary vascular smooth muscle cells as well as primary human endothelial cells was increased up to 15-fold with the RGD-modified vector. Competition experiments with recombinant knob protein and different RGD peptides indicated that the RGD-mediated transduction was Coxsackie and Adenovirus receptor (CAR)-independent and involved integrin alpha(v)beta(5). The use of fiber-modified helper viruses in the last amplification step of HC-Ad vector production allows for convenient and efficient targeting of these vectors towards different cell types. Targeting strategies will increase the spectrum of applications for HC-Ad vectors and will further add to their safety.     

Genetic manipulations of adenovirus type 5 fiber resulting in liver tropism attenuation

The development of genetically modified adenoviral vectors capable of specifically transducing a given cell population requires the addition and functional presentation of particular tropism determinants within the virus capsid, together with the abrogation of the molecular determinants that dictate their natural tropism in vivo. The human adenovirus serotype 5 (Ad5) first attaches to the cell surface following high-affinity binding of the C-terminal knob of the fiber capsid protein to the coxsackie and adenovirus receptor (CAR). Here we have assessed whether genetic shortening of the fiber shaft (virus BS1), or replacing the Ad5 fiber shaft and knob with their Ad3 counterparts (virus DB6), could cripple this interaction in vitro and in vivo. A 10-fold decrease in the binding of the modified capsids to soluble CAR was evidenced, which correlated with a similar reduction of their ability to transduce CAR-positive cells in vitro. The ability of BS1 to interact with cellular integrins was also impaired, suggesting that the penton base and the short-shafted fiber when embedded in the capsid preclude each other from efficiently interacting with their cognate cell surface receptors (CAR and integrins respectively). BS1 and DB6 intravenous injections in mice further supported a profound impairment of the ability of the capsid-modified viruses to transduce the liver as demonstrated by a 10-fold reduction of intracellular viral DNA and transgene expression. Interestingly enough, the host humoral response was also specifically weakened in BS1- and DB6-inoculated animals. Taken together, these observations indicate that (i) fiber shortening and (ii) pseudo-typing of Ad5-based vectors with the shaft and knob from non-CAR-binding serotypes constitute two promising strategies to successfully attenuate their native tropism in vitro and most importantly in vivo.     

Downregulation of human CD46 by adenovirus serotype 35 vectors

Human CD46 (membrane cofactor protein), which serves as a receptor for a variety of pathogens, including strains of measles virus, human herpesvirus type 6 and Neisseria, is rapidly downregulated from the cell surface following infection by these pathogens. Here, we report that replication-incompetent adenovirus (Ad) serotype 35 (Ad35) vectors, which belong to subgroup B and recognize human CD46 as a receptor, downregulate CD46 following infection. A decline in the surface expression of CD46 in human peripheral blood mononuclear cells was detectable 6 h after infection, and reached maximum (72%) 12 h after infection. Ad35 vector-induced downregulation of surface CD46 levels gradually recovered after the removal of Ad35 vectors, however, complete recovery of CD46 expression was not observed even at 96 h after removal. The surface expression of CD46 was also reduced after incubation with fiber-substituted Ad serotype 5 (Ad5) vectors bearing Ad35 fiber proteins, ultraviolet-irradiated Ad35, vectors and recombinant Ad35 fiber knob proteins; in contrast, conventional Ad5 vectors did not induce surface CD46 downregulation, suggesting that the fiber knob protein of Ad35 plays a crucial role in the downregulation of surface CD46 density. These results have important implications for gene therapy using CD46-utilizing Ad vectors and for the pathogenesis of Ads that interact with CD46.     

KLIANNTRV是结核抗原Ag85A的HLA-A*0201限制性CTL表位

目的鉴定结核杆菌抗原Ag85A的HLA-A*0201限制性CTL优势表位。方法采用数据库SYFPEITHI初步预测结核抗原Ag85A的HLA-A*0201限制性CTL表位;经流式细胞术分析抗原肽与HLA-A*0201的亲和力;经时间荧光分辨法检测患者外周血单个核细胞(PBMCs)对抗原肽的增殖反应;最后通过细胞毒实验逐步鉴定Ag85A的HLA-A*0201限制性CTL预测的表位。结果实验证明,预测的位于Ag85A氨基酸序列(242-250aa)的肽表位与HLA-A*0201具有较高的亲和力。结论筛选出的KLIANNTRV(242-250aa)是结核杆菌抗原Ag85A的HLA-A*0201限制性CTL优势表位。     

Gal-Gal pyelonephritis Escherichia coli pili linear immunogenic and antigenic epitopes

The linear immunogenic and antigenic structure of E. coli Gal-Gal pili from the recombinant strain HU 849 was investigated with nine synthetic peptides corresponding to regions of the pilus sequence predicted to contain hydrophilic beta-turns. Five peptides, as bovine serum albumin conjugates, were found by anti-HU 849 pilus serum and were thus designated "immunogenic epitopes." Peptides corresponding to R 25-38, R 38-50, and R 48-61 (which jointly comprise the single intramolecular disulfide loop), and R 103-116, were bound in low titer. A prominent immunogenic epitope was specified by a peptide corresponding to R 65-75. Four peptides, as thyroglobulin conjugates, elicited antisera in rabbits that bound intact HU 849 pili. These were designated "antigenic epitopes." Two prominent antigenic epitopes were localized to peptides corresponding to R 5-12 and R 93-104, whereas peptides corresponding to R 65-75 and R 119-131 represented two minor antigenic epitopes. None of the peptide antisera bound Gal-Gal pili from heterologous strains except anti-R 93-104 and anti-R 5-12. In 8 of the 10 Gal-Gal-binding pyelonephritis isolates tested, anti-R 5-12 detected a protein with an apparent molecular weight of 18,000 co-migrating with several Gal-Gal pili. Anti-R 93-104 detected a corresponding protein in 4 of 8 fecal and 7 of 12 pyelonephritis Gal-Gal-binding isolates; however, it also bound apparently unrelated proteins of higher molecular weight.     

Conversion of an immunogenic human immunodeficiency virus (HIV) envelope synthetic peptide to a tolerogen in chimpanzees by the fusogenic domain of HIV gp41 envelope protein

The fusogenic (F) domain of human immunodeficiency virus (HIV) gp41 envelope (env) protein has sequence similarities to many virus and mediates the fusion of HIV-infected cells. During a survey of the immunogenicity of HIV env peptides in chimpanzees, we have observed that HIV peptide immunogenicity was dramatically altered by the NH2- terminal synthesis of the gp41 F domain to an otherwise immunogenic peptide. We compared two hybrid peptide types comprised of T helper (Th) and B cell epitopes of HIV gp120 env protein for their immunogenicity in chimpanzees. The Th-B epitope hybrid peptides contained the HIV gp120 Th cell determinant, T1 (amino acids [aa] 428- 440)-synthesized NH2 terminal to gp120 V3 loop peptides, which contain B cell epitopes that induce anti-HIV-neutralizing antibodies (SP10IIIB [aa 303-321] and SP10IIIB [A] [aa 303-327]). The F-Th-B peptide contained the HIV gp41 F domain of HIVIIIB gp41 (aa 519-530)- synthesized NH2 terminal to the Th-B peptide. Whereas Th-B peptides were potent immunogens for chimpanzee antibody and T cell-proliferative responses, the F-Th-B peptide induced lower anti-HIV gp120 T and B cell responses. Moreover, immunization of chimpanzees with F-Th-B peptide but not Th-B peptides induced a significant decrease in peripheral blood T lymphocytes (mean decrease during immunization, 52%; p < 0.02). Chimpanzees previously immunized with F-Th-B peptide did not respond well to immunization with Th-B peptide with T or B cell responses to HIV peptides, demonstrating that the F-Th-B peptide induced immune hyporesponsiveness to Th and B HIV gp120 env determinants. These observations raise the hypothesis that the HIV gp41 env F domain may be a biologically active immunoregulatory peptide in vivo, and by an as yet uncharacterized mechanism, promotes primate immune system hyporesponsiveness to otherwise immunogenic peptides.     

Efficient gene delivery in human and rodent mast cells using adenovirus vectors

Mast cells (MCs) have been shown to play an important role in immunoglobulin E (IgE)-associated immediate hypersensitivity and innate immunity by producing a variety of lipid mediators and cytokines. An efficient gene-delivery system is indispensable for elucidation of these mechanisms. In the present study, human and rodent MCs were transduced with various types of modified adenovirus (Ad) vectors. Fiber modification in Ad vectors significantly improved the transduction efficiencies in MCs. A fiber-substituted Ad serotype 5 (Ad5) vector containing Ad serotype 35 (Ad35) fiber proteins (Ad5F35) and an Ad35 vector, both of which transduce cells via human CD46, mediated 9.9-fold and 10.1-fold higher transduction efficiencies than conventional Ad5 vectors in the human mast cell line LAD2 among the Ad vectors. Ad5F35 and Ad35 vectors also efficiently transduced bone marrow-derived MCs (BMMCs) prepared from human CD46-transgenic (CD46TG) mice. The rat mast cell line RBL-2H3 were most efficiently transduced with a fiber-mutant Ad5 vector containing the Arg-Gly-Asp (RGD) peptide in the HI loop (Ad-RGD) of the fiber knob. Transduction with the Ad vectors did not induce degranulation or inflammatory cytokine production in the MCs. These results indicate that Ad vectors, including fiber-mutant Ad vectors, are effective gene-delivery tools for MCs.     

结核杆菌抗原Rv0173的HLA-A*0201限制性CTL表位的预测及鉴定

目的 鉴定结核杆菌(Mycobacterium tuberculosis,Mtb)抗原Rv0173中的HLA-A*0201限制性CTL表位.方法 应用数据库SYFPETTHI预测结核杆菌Rv0173中可能存在的HLA-A*0201限制性CTL表位,经流式细胞术分析各抗原肽与HLA-A*0201的亲合力,经时间分辨荧光法检测外周血单个核细胞(PBMCs)对各抗原肽产生的增殖反应,经细胞毒性实验研究各抗原肽诱导的特异性T细胞的细胞毒杀伤活性,逐步鉴定Rv0173的HLA-A*0201限制性CTL表位.结果 位于Rv0173氨基酸序列肽3(21-30aa)和抗原肽7(161-170aa)与HLA-A*0201分子具有较高的亲合力,并都能刺激HLA-A*0201阳性个体PBMCs增殖,并诱导产生特异性杀伤活性.结论 肽3(RLSQSADQYL)(21-30aa)和肽7(LLRGGGLVNL)(161-170aa)是抗原Rv0173上HLA-A*0201限制性CTL的优势表位,可作为结核疫苗设计的候选表位.