An innovative lab-scale production for a novel therapeutic DNA vaccine candidate against rheumatoid arthritis.

BACKGROUND: Recent therapeutic-plasmid DNA vaccine strategies for rheumatoid arthritis (RA) have significantly improved. Our pcDNA-CCOL2A1 vaccine is the most prominent and the first antigen-specific tolerising DNA vaccine with potent therapeutic and prophylactic effects compared with methotrexate (MTX), the current "gold standard" treatment for collagen-induced arthritis (CIA). This study developed a highly efficient, cost-effective, and easy-to-operate system for the lab-scale production of endotoxin-free supercoiled plasmids with high quality and high yield. Based on optimised fermentation culture, we obtained a high yield of pcDNA-CCOL2A1 vaccine by PEG/MgCl2 precipitation and TRION-114. We then established a method for quality control of the pcDNA-CCOL2A1 vaccine. Collagen-induced arthritis (CIA) model rats were subjected to intramuscular injection of the pcDNA-CCOL2A1 vaccine (300 µg/kg) to test its biological activity. RESULTS: An average yield of 11.81 ± 1.03 mg purified supercoiled plasmid was obtained from 1 L of fermentation broth at 670.6 ± 57.42 mg/L, which was significantly higher than that obtained using anion exchange column chromatography and a commercial purification kit. Our supercoiled plasmid had high purity, biological activity, and yield, conforming to the international guidelines for DNA vaccines. CONCLUSION: The proposed innovative downstream process for the pcDNA-CCOL2A1 vaccine can not only provide a large-scale high-quality supercoiled plasmid DNA for preclinical research but also facilitate further pilot-scale and even industrial-scale production of pcDNA-CCOL2A1 vaccine.

Transformed Salmonella typhimurium SL7207/pcDNA-CCOL2A1 as an orally administered DNA vaccine.

The use of attenuated bacteria for oral delivery of DNA vaccines is a recent innovation. We designed and constructed the naked plasmid DNA vaccine pcDNA-CCOL2A1, which effectively prevented and treated a rheumatoid arthritis model by inducing immunotolerance. We aimed to ensure a reliable, controllable dosage of this oral DNA vaccine preparation and establish its stability. We transformed pcDNA-CCOL2A1 via electroporation into attenuated Salmonella typhimurium SL7207. A resistant plate assay confirmed the successful construction of the transformed strain of the SL7207/pcDNA-CCOL2A1 oral DNA vaccine. We verified its identification and stability in vitro and in vivo. Significant differences were observed in the characteristics of the transformed and blank SL7207 strains. No electrophoretic restriction patterns or direct sequencing signals were observed in the original extract of the transformed strain. However, target gene bands and sequence signals were successfully detected after PCR amplification. CCOL2A1 expression was detected in the ilea of BALB/c mice that were orally administered SL7207/pcDNA-CCOL2A1. The pcDNA-CCOL2A1 plasmid of the transformed strain was retained under the resistant condition, and the transformed strain remained stable at 4 °C for 100 days. The concentration of the strain harboring the pcDNA-CCOL2A1 plasmid was stable at 109 CFU/mL after 6-8 h of incubation. The results demonstrated that the transformed strain SL7207/pcDNA-CCOL2A1 can be expressed in vivo, has good stability, and may be used to prepare the oral DNA vaccine pcDNA-CCOL2A1 with a stable, controllable dosage and the capacity to provide oral immunization. This vehicle can effectively combine both oral immunotolerance and DNA vaccination.

Recombination and mutation shape variations in the major histocompatibility complex.

The major histocompatibility complex (MHC) is closely associated with numerous diseases, but its high degree of polymorphism complicates the discovery of disease-associated variants. In principle, recombination and de novo mutations are two critical factors responsible for MHC polymorphisms. However, direct evidence for this hypothesis is lacking. Here, we report the generation of fine-scale MHC recombination and de novo mutation maps of ∼5 Mb by deep sequencing (> 100×) of the MHC genome for 17 MHC recombination and 30 non-recombination Han Chinese families (a total of 190 individuals). Recombination hotspots and Han-specific breakpoints are located in close proximity at haplotype block boundaries. The average MHC de novo mutation rate is higher than the genome-wide de novo mutation rate, particularly in MHC recombinant individuals. Notably, mutation and recombination generated polymorphisms are located within and outside linkage disequilibrium regions of the MHC, respectively, and evolution of the MHC locus was mainly controlled by positive selection. These findings provide insights on the evolutionary causes of the MHC diversity and may facilitate the identification of disease-associated genetic variants.

Different protective efficacies of a novel antigen-specific DNA vaccine encoding chicken type â ¡ collagen via intramuscular, subcutaneous, and intravenous vaccination against experimental rheumatoid arthritis.

Tolerizing DNA vaccines encoding key autoantigens are one of emerging strategies for the treatment of rheumatoid arthritis (RA). Among these vaccines, the most representative is pcDNA-CCOL2A1, an antigen-specific DNA vaccine encoding chicken type Ⅱ collagen (CCⅡ) with significant therapeutic and prophylactic efficacy in collagen-induced arthritis (CIA) rat models. We compared the in situ expression levels of CCOL2A1-mRNA and CCⅡ protein and the protective efficacies against CIA after a single dose (300 µg/kg) of this vaccine via intramuscular (IM), subcutaneous (SC) and intravenous (IV) vaccinations. The IM vaccination routes resulted in good protective efficacies in terms of decreasing CIA incidence and severity and significantly improved radiographic and histopathologic findings and scores of joints. Furthermore, IM, SC, and IV vaccinations markedly decreased serum levels of anti-type Ⅱ collagen (CⅡ) IgG antibodies, but only IM vaccination significantly reduced serum levels of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody. The vaccine exhibited a continuous CCOL2A1-mRNA expression in the tail and abdominal subcutaneous tissue injection sites, but no CCOL2A1-mRNA signal was observed in muscle. Strikingly, CCⅡ protein expression levels at the three injection sites were comparable with minimal variation. IM administration may be considered the preferred route for RA treatment in clinical practice.

Dynamic profiles, biodistribution and integration evaluation after intramuscular/intravenous delivery of a novel therapeutic DNA vaccine encoding chicken type II collagen for rheumatoid arthritis in vaccinated normal rodent.

BACKGROUND: The persistence, biodistribution, and risk of integration into the host genome of any new therapeutic DNA vaccine must be established in preclinical studies. We previously developed the DNA vaccine pcDNA-CCOL2A1 encoding chicken type II collagen (CCII) for the treatment of rheumatoid arthritis (RA). In the present study, we characterized its dynamic profile, biodistribution, and potential for genomic DNA integration in normal vaccinated rodent. RESULTS: A real-time quantitative PCR analysis (RT-qPCR) of animals administered a single dose of pcDNA-CCOL2A1 (300 µg/kg by intramuscular injection) showed that CCOL2A1 mRNA level in the blood peaked between 2 and 6 h post-immunization and then rapidly declined, and was undetectable between day 1-42. CCOL2A1 transcript was detected at the muscle injection site on days 3-14 post-immunization. Starting from day 14, the transcript was detected in the heart, liver, lung, and kidney but not in the spleen or thymus, and was expressed only in the lung on day 28. There was no CCOL2A1 mRNA present in the testes or ovaries at any time point. Non-invasive in vivo fluorescence imaging revealed CCII protein expression from 2 h up to day 10 and from 2 h up to day 35 after administration of pcDNA-CCOL2A1 via the intravenous and intramuscular routes, respectively; the protein had disappeared by day 42. Importantly, CCOL2A1 was not integrated into the host genome. CONCLUSIONS: These results indicate that pcDNA-CCOL2A1 vaccine is rapidly cleared within a short period of time and is therefore safe, and merits further development as a therapeutic vaccine for RA treatment.

Vaccination with a Novel Antigen-Specific Tolerizing DNA Vaccine Encoding CCOL2A1 Protects Rats from Experimental Rheumatoid Arthritis.

Antigen-specific tolerizing DNA vaccines are one of the most promising strategies for rheumatoid arthritis (RA) treatment. They act by inducing potent immune tolerance instead of generalized immunosuppression. Recently, we developed a novel antigen-specific tolerizing DNA vaccine pcDNA-CCOL2A1 coding for chicken type II collagen (CCII) and confirmed its potent therapeutic efficacy in an established rat model of collagen-induced arthritis (CIA). Here we report the prophylactic vaccination efficacy of a single 300 µg/kg dose of pcDNA-CCOL2A1 against CIA incidence, severity, and onset. CCOL2A1 transcripts were detected in the blood of CIA rats 14-42 days after intramuscular injection by 300 µg/kg pcDNA-CCOL2A1. The expression of CCOL2A1 transcripts increased quickly on day 21, peaked at day 28, and then gradually decreased thereafter. Importantly, a single prophylactic vaccination of pcDNA-CCOL2A1 14 days before CIA establishment significantly reduced CIA incidence and severity, deferred its onset, and was as efficacious as the current gold standard drug, methotrexate. The marked effects on CIA incidence and severity closely corresponded to the expression of CCOL2A1. Furthermore, prophylactic vaccination with pcDNA-CCOL2A1 markedly decreased serum content of anti-type II collagen (CII) immunoglobulin G (IgG) antibodies, induced Th1-to-Th2 and Tc1-to-Tc2 shifts, and decreased the percentages of CD4+CD29+ and Th17 T cells. Prophylactic vaccination with pcDNA-CCOL2A1 also downregulated various Th1 cytokines, while upregulating both the Th2-type cytokine interleukin-10 and the Th3-type cytokine transforming growth factor ß. Our results indicate that the pcDNA-CCOL2A1 DNA vaccine acts as a highly efficient inducer of specific immunotolerance that could be a promising option for RA treatment in the near future.

Optimization of fermentation conditions for an Escherichia coli strain engineered using the response surface method to produce a novel therapeutic DNA vaccine for rheumatoid arthritis.

BACKGROUND: Fermentation condition optimization and nutrients screening are of equal importance for efficient production of plasmid DNA vaccines. This directly affects the downstream purification and final quality and yield of plasmid DNA vaccines. The present study aimed to optimize the fermentation conditions for high-throughput production of therapeutic DNA vaccine pcDNA-CCOL2A1 by engineered Escherichia coli DH5α, using the response surface method (RSM). RESULTS: We hypothesized that optimized fermentation conditions significantly increase the yield of pcDNA-CCOL2A1 therapeutic DNA vaccine, a novel DNA vaccine for treating rheumatoid arthritis (RA). Single-factor analysis was performed to evaluate the optimal basal culture medium from LB, 2 × YT, TB, M9 (Glycerol) and M9 (Glucose), respectively. Thereafter, the Plackett-Burman design (PBD) was used to ascertain the three most significant factors affecting the vaccine yields, followed by the paths of steepest ascent to move to the nearest region of maximum response. Initial screening through the PBD revealed that the most key factors were peptone, mannitol, and inoculum concentration. Subsequent use of RSM was further optimized for the production of therapeutic DNA vaccine pcDNA-CCOL2A1 through Box-Behnken design (BBD). The final optimized fermentation conditions were as follows: peptone, 25.86 g/L; mannitol, 8.08 g/L; inoculum concentration, OD = 0.36. Using this statistical experimental design, the yield of therapeutic DNA vaccine pcDNA-CCOL2A1 markedly increased from 223.37 mg/L to339.32 mg/L under optimal conditions, and a 51.9% increase was observed compared with the original medium. CONCLUSIONS: The present results provide a basis for further production of high-quality and high-yield therapeutic DNA vaccine pcDNA-CCOL2A1 in pilot-scale and even industrial-scale.

Molecular assembly of recombinant chicken type II collagen in the yeast Pichia pastoris.

Effective treatment of rheumatoid arthritis can be mediated by native chicken type II collagen (nCCII), recombinant peptide containing nCCII tolerogenic epitopes (CTEs), or a therapeutic DNA vaccine encoding the full-length CCOL2A1 cDNA. As recombinant CCII (rCCII) might avoid potential pathogenic virus contamination during nCCII preparation or chromosomal integration and oncogene activation associated with DNA vaccines, here we evaluated the importance of propeptide and telopeptide domains on rCCII triple helix molecular assembly. We constructed pC- and pN-procollagen (without N- or C-propeptides, respectively) as well as CTEs located in the triple helical domain lacking both propeptides and telopeptides, and expressed these in yeast Pichia pastoris host strain GS115 (his4, Mut+) simultaneously with recombinant chicken prolyl-4-hydroxylase α and ß subunits. Both pC- and pN-procollagen monomers accumulated inside P. pastoris cells, whereas CTE was assembled into homotrimers with stable conformation and secreted into the supernatants, suggesting that the large molecular weight pC-or pN-procollagens were retained within the endoplasmic reticulum whereas the smaller CTEs proceeded through the secretory pathway. Furthermore, resulting recombinant chicken type II collagen pCα1(II) can induced collagen-induced arthritis (CIA) rat model, which seems to be as effective as the current standard nCCII. Notably, protease digestion assays showed that rCCII could assemble in the absence of C- and N-propeptides or telopeptides. These findings provide new insights into the minimal structural requirements for rCCII expression and folding.

A complex role of anthrax toxin receptor 2 polymorphisms and capillary morphogenesis protein 2 in ankylosing spondylitis pathogenesis.

This study investigated the role of anthrax toxin receptor 2 (ANTXR2) gene polymorphisms and capillary morphogenesis protein 2 (CMG2) expression in susceptibility and pathogenesis to ankylosing spondylitis (AS) in the Han Chinese in Beijing. A case-control study was performed using 602 AS patient samples meeting the revised New York criterion and 619 matched controls from Han Chinese individuals. Nineteen single-nucleotide polymorphisms (SNPs) of ANTXR2 genes were selected and genotyped using the Sequenom iPlex platform. Real-time polymerase chain reaction and flow cytometry were performed to investigate the impact of SNP polymorphisms on ANTXR2 transcription and CMG2 expression, respectively. The association of variants with AS was examined with UNPHASED 3.1.5. A novel association was observed between AS and three SNPs in the ANTXR2 gene (rs4690127, rs6823031, and rs4333130; P = 0.004, 0.011, and 0.013, respectively), confirming the association between rs433130 and AS in the Han Chinese. The strongest haplotype association was observed with rs4690127-rs6823031-rs4333130 (P = 2.5 × 10(-4)). rs6534639 and rs4333130 showed a cis-interaction (P = 0.027) in AS. ANTXR2 messenger RNA (mRNA) expression was significantly higher in the AS group than in the control group (P = 0.039). CMG2 expression in the lipopolysaccharide (LPS)-stimulated group was significantly lower than that in the control group (P = 0.018). This study reports a novel association between ANTXR2 and AS in the Han Chinese. ANTXR2 genetic polymorphisms affect ANTXR2 mRNA transcription and CMG2 expression. The opposing results observed for ANTXR2 transcription and CMG2 expression suggest a complex role of ANTXR2 polymorphisms in AS pathogenesis.

Three-dimensional structure discrepancy between HLA alleles for effective prediction of aGVHD severity and optimal selection of recipient-donor pairs: a proof-of-concept study.

The optimal selection of recipient-donor pair and accurate prediction of acute graft-versus-host disease (aGVHD) severity are always the two most crucial works in allogeneic hematopoietic stem cell transplantation (allo-HSCT), which currently rests mostly with HLA compatibility, the most polymorphic loci in the human genome, in clinic. Thus, there is an urgent need for a rapid and reliable quantitative system for optimal recipient-donor pairs selection and accurate prediction of aGVHD severity prior to allo-HSCT. For these reasons, we have developed a new selection/prediction system for optimal recipient-donor selection and effective prediction of aGVHD severity based on HLA three-dimensional (3D) structure modeling (HLA-TDSM) discrepancy, and applied this system in a pilot randomized clinical allo-HSCT study. The 37 patient-donor pairs in the study were typed at low- and high-resolution levels for HLA-A/-B/-DRB1/-DQB1 loci. HLA-TDSM system covering the 10000 alleles in HLA class I and II consists of the revised local and coordinate root-mean-square deviation (RMSD) values for each locus. Its accuracy and reliability were confirmed using stably transfected Hmy2.CIR-HLA-B cells, TCR Vß gene scan, and antigen-specific alloreactive cytotoxic lymphocytes. Based on the preliminary results, we theoretically defined all HLA acceptable versus unacceptable mismatched alleles. More importantly, HLA-TDSM enabled a successful retrospective verification and prospective prediction for aGVHD severity in a pilot randomized clinical allo-HSCT study of 32 recipient-donor transplant pairs. There was a strong direct correlation between single/total revised RMSD and aGVHD severity (92% in retrospective group vs 95% in prospective group). These results seem to be closely related to the 3D structure discrepancy of mismatched HLA-alleles, but not the number or loci of mismatched HLA-alleles. Our data first provide the proof-of-concept that HLA-TDSM is essential for optimal selection of recipient-donor pairs and effective prediction of aGVHD severity before allo-HSCT.

Potent control of acute graft-versus-host disease lethality after immunization with a novel DNA vaccine targeted to B7-1/CD28 costimulatory signaling pathway.

A major challenge associated with allogeneic hematopoietic stem cell transplantation is effective prevention and/or attenuation of symptoms associated with acute graft-versus-host disease (aGVHD) that can result from a failure of either host and/or donor CD4(+)CD25(+) regulatory T (Tr) and CD8(+)CD28 suppressor T (Ts) cells to dampen immunopathogenic responses mediated by alloreactive donor CD4(+)CD28(+) Th1 (Th1) and CD8(+)CD28(-) Tc1 (Tc1) cell-mediated inflammatory processes. Considering the crucial role of CD28/B7-1 costimulatory signal pathway in development, activation, differentiation, and function of these T subsets, we developed a targeted DNA vaccine encoding the Pseudomonas exotoxin-A and the B7-1 molecule that could act as both an antagonist to Th1-mediated and Tc1-mediated responses while concomitantly acting as an agonist stimulating Tr-mediated and Ts-mediated responses as a strategy for reducing aGVHD-associated lethality. A single intramuscular injection with this vaccine significantly increased Tr and Ts levels in a murine aGVHD model. In addition, immunized mice presented with significantly diminished Th1-cytokines interferon-γ and interleukin-2 response and a moderately upregulated Th2-cytokine interleukin-10 and Th3-cytokine transforming growth factor-ß response. More importantly, vaccination significantly reduced aGVHD, measured by significantly extended mean survival times, decreased mean weight loss, recovery of peripheral leukocyte numbers, disease presentation associated with mild-moderate histopathologic changes, a balanced Th1-Th2-Th3-cytokine responses and functional Tr-mediated and Ts-mediated regulatory/suppressor mechanisms at levels more potent than observed in animals treated with cyclosporine A+methotrexate. Our data first provide the proof-of-principal that B7-1-PE40KDEL targeted DNA vaccine represents a prophylactic approach for reducing alloreactive Th1-mediated and Tc-mediated aGVHD lethality by CD28/B7-1 axis.

Potent antirheumatic activity of a new DNA vaccine targeted to B7-2/CD28 costimulatory signaling pathway in autoimmune arthritis.

Rheumatoid arthritis is a proinflammatory autoimmune disease attributed to failure of both CD4(+)CD25(+) regulatory T (Tr) and CD8(+)CD28(-) suppressor T (Ts) cells to control autoreactive CD4(+)CD28(+) Th1 (Th1) and autoantibody-producing B cells. Here we show a single intramuscular injection of our novel targeted DNA vaccine encoding Pseudomonas exotoxin A and costimulatory molecule B7-2 without autoantigens in a collagen-induced arthritis model simultaneously increased Tr and Ts cells and selectively decreased autoreactive Th1 cells. The vaccine induced a shift from Th1 to Th2 and Th3 cellular and cytokine profiles and a decrease in CD4(+)/CD8(+) cell ratios. Importantly, the vaccine showed potent antirheumatic activity by clinical and other examinations such as X-ray, histopathology, and anti-type II collagen IgG levels and was comparable to methotrexate, the current "gold standard" treatment. As an effective stimulator of both Tr and Ts cells and a specific suppressor of autoreactive Th1 cells, this vaccine is a promising therapeutic approach for rheumatoid arthritis.

[Study on allelic characteristics of "homozygote" resulted from low resolution genotyping of HLA-Cw locus].

OBJECTIVE: To study the allelic characteristics of "homozygote" resulted from low resolution genotyping of HLA-Cw locus and to provide more precise typing data for clinical transplantation. METHODS: Forty three related allogeneic hematopoietic stem cell transplantation(allo-HSCT) donors and patients with HLA-Cw * 03, Cw * 07 homozygote, which were the most common gene groups in Chinese population, identified by low resolution genotyping level were retyped by high resolution PCR-SSP genotyping method, and three dimensional structure modelling was also made by using a solely developed HLA three-dimensional matching software (HLA strucMark version 1.0) to evaluate the effect of differences between two mismatched alleles and its relationship with GVHD occurrence. RESULTS: The typing results of high resolution level demonstrated that the confirmed allelic homozygotes for Cw * 03 and Cw * 07 were 14% and 43%, respectively, while the others were all heterozygotes. The ambiguous typing results could be confirmed by family data study or by high resolution typing methods when there was no family data available, Three-dimensional modeling results of the mismatched alleles undetected in low resolution typing level indicated that family data study or high resolution PCR-SSP genotyping were important in preventing graft-versus-host disease. CONCLUSIONS: When HLA-Cw homozygote results were found in low resolution genotyping method, the results should be reconfirmed by family data study or by high resolution typing methods to provide precise typing results for avoiding severe graft-versus-host disease.

Construction and characterization of a novel DNA vaccine that is potent antigen-specific tolerizing therapy for experimental arthritis by increasing CD4+CD25+Treg cells and inducing Th1 to Th2 shift in both cells and cytokines.

Currently available treatments for rheumatoid arthritis (RA) are often ineffective in ameliorating the progression of disease, particularly the invasive destruction of articular cartilage and bone, and RA remains incurable. Therefore, vaccinotherapy of RA with an antigen-specific tolerizing DNA vaccine may offer new promise for overcoming this difficulty. Using recombinant technology, the DNA sequences encoding chicken type II collagen (CCOL2A1) with deleted N-propeptides were obtained from the plasmid pPIC9K/pCalpha(1)(II), and then cloned into pcDNA3.1(+). The resulting recombinant plasmid pcDNA-CCOL2A1 was produced in Escherichia coli, purified, characterized and used as a tolerizing DNA vaccine for the treatment of collagen-induced arthritis (CIA). Therapeutic efficacy and potential action mechanisms of pcDNA-CCOL2A1 tolerizing DNA vaccine against CIA were studied. Here we demonstrate that a single intravenous treatment with novel tolerizing DNA vaccine pcDNA-CCOL2A1 can induce potent immune tolerance against CIA. The efficacy of this therapy was verified by clinical visual scoring, radiographic X-ray, histopathological examination, and anti-CII IgG levels. Furthermore, the action mechanism behind this efficacy can be at least partially attributed to increased CD4(+)CD25(+) T regulatory cells, which specifically down-modulate the T lymphocyte proliferative response to CCII, induce a shift of Th1 to Th2 cells, as well as down-regulate Th1-cytokine TNF-alpha, while up-regulating both Th2-cytokine IL-10 and Th3-cytokine TGF-beta. More importantly, pcDNA-CCOL2A1 alone seems to be as effective as the current "golden standard" treatment, methotrexate (MTX). Taken together, these results suggest that we have successfully developed a novel tolerizing DNA vaccine encoding CCII, which is the first description of a tolerizing DNA vaccine encoding CCII for antigen-specific tolerizing therapy but not prophylactic against CIA.

A novel recombinant peptide containing only two T-cell tolerance epitopes of chicken type II collagen that suppresses collagen-induced arthritis.

Immunotherapy of rheumatoid arthritis (RA) using oral-dosed native chicken or bovine type II collagen (nCII) to induce specific immune tolerance is an attractive strategy. However, the majority of clinical trials of oral tolerance in human diseases including RA in recent years have been disappointing. Here, we describe a novel recombinant peptide rcCTE1-2 which contains only two tolerogenic epitopes (CTE1 and CTE2) of chicken type II collagen (cCII). These are the critical T-cell determinants for suppression of RA that were first developed and used to compare its suppressive effects with ncCII on the collagen-induced arthritis (CIA) model. The rcCTE1-2 was produced using the prokaryotic pET expression system and purified by Ni-NTA His affinity chromatography. Strikingly, our results showed clearly that rcCTE1-2 was as efficacious as ncCII at the dose of 50 microg/kg/d. This dose significantly reduced footpad swelling, arthritic incidence and scores, and deferred the onset of disease. Furthermore, rcCTE1-2 of 50 microg/kg/d could lower the level of anti-nCII antibody in the serum of CIA animals, decrease Th1-cytokine INF-gamma level, and increase Th3-cytokine TGF-beta(1) produced level by spleen cells from CIA mice after in vivo stimulation with ncCII. Importantly, rcCTE1-2 was even more potent than native cCII, which was used in the clinic for RA. Equally importantly, the findings that the major T-cell determinants of cCII that are also recognized by H-2(b) MHC-restricted T cells have not previously been reported. Taken together, these results suggest that we have successfully developed a novel recombinant peptide rcCTE1-2 that can induce a potent tolerogenic response in CIA.

[Prokaryotic expression of HLA-B * 2705 heavy chain and identification for its activity].

In order to investigate the expression of heavy chain of HLA-B * 2705 in prokaryotic system and identify its activity, the extra-membrane gene fragment of HLA-B * 2705 was amplified from full-length HLA-B*2705 cDNA by PCR and cloned into pGEM-T vector. After identification by sequencing, the prokaryotic expressing vector pET32a (+)-B * 2705 was constructed. The antigenic activity of expressed protein was identified by Western blot and antibody blocking reaction. The results indicated that the fused HLA-B * 2705 protein expression with high efficiency was obtained. The expressed product was more than 50% of the total bacteria protein. The antigenic activity of expressed protein was confirmed by Western blot and antibody blocking reaction. It is concluded that HLA-B * 2705 fusion protein are obtained as basis for the further studies.

[Haplotype and linkage analysis of HLA-I classical genes in Chinese Han population].

The aim of this study was to investigate the parameters of gene frequencies, haplotype frequencies and linkage disequilibrium of HLA-A, -B, -Cw in HLA classical I loci for Chinese Han population. HLA-A, HLA-B and HLA-Cw loci were genotyped in 1014 unrelated China people using low resolution PCR-SSP typing method, and their genetic parameters were analyzed by statistic methods. The results indicated that among all the detected HLA-I genes, A*02 (0.33), A*11 (0.24), B*15 (0.14), B*13 (0.13), Cw*03 (0.25) and Cw*07 (0.18) were the popular gene groups distributing in Chinese Han population, and A*02-B*46 (0.071), A*11-B*15 (0.051), A*02-Cw*01 (0.084), A*11-Cw*03 (0.079), B*46-Cw*01 (0.095) and B*13-Cw*03 (0.071) were the predominant haplotypes in Han population. Additionally, A*02-B*46, A*30-B*13, A*30-Cw*06, A*02-Cw*01, B*46-Cw*01 and B*58-Cw*03 were statistically significant with strong linkage disequilibrium. While A*02-B*15, A*02-B*40, A*24-Cw*03, A*02-Cw*03 and A*31-Cw*03 were in low linkage disequilibrium, among them A*24-Cw*03 appeared frequently in HLA recombination events. In addition, A*02-B*46-Cw*01 (0.075), A*30-B*13-Cw*06 (0.046), A*11-B*13-Cw*03 (0.045), A*33-B*58-Cw*03 (0.044), A*11-B*15-Cw*08 (0.027), A*02-B*38-Cw*07 (0.023) and A*11-B*40-Cw*07 (0.022) were the main extended haplotypes in Han population. In conclusions, this study investigated systematically the genetic polymorphism features of Chinese Han population, which may provide useful genetic parameters for researches in colonial evolution, clinical transplantation and disease susceptibility.

Human leukocyte antigens A and B Loci genotyping by reference strand-mediated conformation analysis in hematopoietic stem cell transplantation donor selection.

Research has been carried out to evaluate the reference strand-mediated conformation analysis (RSCA) typing method on human leukocyte antigen (HLA)-A and -B loci matching in donor selection for hematopoietic stem cell transplantation (HSCT). Twenty standard DNA samples from the RSCA program of the 13th International Histocompatibiliy Working Group, and 124 DNA samples extracted from peripheral blood cells of 39 patients and 85 related potential donors were typed both by RSCA and polymerase chain reaction sequence-specific primer (PCR-SSP) for their HLA-A and -B genes. The ambiguous results were further confirmed by sequence-based typing (SBT). HLA-A and -B genotypes assigned by RSCA correlated well with PCR-SSP and the repetitive rate of RSCA was 100%. In our study, 33/84 (39%) and 67/90 (72.8%) RSCA genotyping results of HLA-A and -B loci could be typed to allelic level, respectively. RSCA can detect mismatches that are not routinely identified by the PCR-SSP method and can detect the chimerism status after patients have gone through HLA-mismatched HSCT. Eight ambiguous samples were confirmed by SBT and the results indicated that RSCA was more accurate than low-resolution PCR-SSP and its database should be improved. RSCA is reproducible, has a high resolution, is able to detect chimerism follow-up after HLA-mismatched HSCT, and is a useful approach for donor selection with some insufficiencies to be improved.