Mingli Fang

MF59 formulated with CpG ODN as a potent adjuvant of recombinant HSP65-MUC1 for inducing anti-MUC1+ tumor immunity in mice

Abstract MF59 is an oil-in-water emulsion adjuvant approved for influenza vaccines for human use in Europe. Due to its Th2 inducing properties, MF59 is seldom tested for cancer vaccines. In this study, MF59 formulated with a C-type CpG oligodeoxynucleotide (YW002) was tested for its Th1 adjuvant activity to induce immune responses to HSP65-MUC1, a recombinant fusion protein incorporating a mycobacterial heat shock protein (HSP65) and mucin 1, cell surface associated (MUC1) derived peptide. Combination of YW002 with MF59 (MF59-YW002) could confer a potent Th1 biasing property to the adjuvant, which enhanced the immunogenicity of HSP65-MUC1 to induce significantly higher levels of specific IgG2c, increased IFN-γ mRNA expression in splenocytes and the generation of antigen-specific cytotoxic T lymphocytes in mice. When prophylactically applied, MF59-YW002 adjuvant containing HSP65-MUC1 inhibited the growth of MUC1+ B16 melanoma and prolonged the survival of tumor-bearing mice. In contrast, adjuvant containing MF59 with HSP65-MUC1 in the absence of YW002, promoted the growth of MUC1+ B16 melanoma in mice. These results suggest that MF59 plus CpG oligodeoxynucleotide might be developed as an efficient adjuvant for tumor vaccines against melanoma, and possibly other tumors.

An oligodeoxynucleotide capable of lessening acute lung inflammatory injury in mice infected by influenza virus.

Infection of influenza virus could induce acute lung inflammatory injury (ALII) that was at least partially caused by excessive innate immune responses. To study whether down-regulating Toll-like receptor (TLR)-mediated innate immune response could lessen influenza virus-induced ALII, a microsatellite DNA mimicking oligodeoxynucleotide (MS ODN), named as SAT05f capable of inhibiting TLR7/9-activation in vitro, was used to treat mice infected with FM1 virus. In parallel, two MS ODNs confirmed with less or no in vitro activities, named as MS19 and MS33, were used as controls. Unexpectedly, SAT05f failed to lessen ALII in the mice, whereas MS19 significantly inhibited the weight loss and displayed dramatic effect on lessening the ALII by reducing consolidation, hemorrhage, intra-alveolar edema and neutrophils infiltration in lungs of the mice. Meanwhile, MS19 could decrease the mortality of influenza virus infected mice and down-regulate TNF-α production in their lungs. The data suggest that MS19 might display its therapeutic role on ALII induced by influenza virus by reducing over-production of TNF-α.

Delivery System of CpG Oligodeoxynucleotides through Eliciting an Effective T cell Immune Response against Melanoma in Mice.

Purpose: In order to improve the immunogenicity of whole tumor cell lysate for tumor vaccine, we have designed a series of CpG ODNs to study their transport and to evaluate their anti-tumor activity in B16 melanoma mouse models. Methods: In this study, we investigated whether C-class CpG ODN (CpG ODN-685) could facilitate tumor cell lysate to induce vigorous anti-tumor activity against tumors in mice both prophylactically and therapeutically. Results: It was found that the combination of tumor cell lysate and CpG ODN-685 could inhibit the growth of B16 melanoma and prolong the survival of tumor-bearing mice. Moreover CpG ODN-685 with the addition of tumor cell lysate can also cause the generation of tumor specific immune memory by inducing specific cytotoxic T lymphocytes and helper T lymphocytes in mice. Conclusion: The results suggest that CpG ODN-685 could be developed as an efficient adjuvant for tumor vaccines against melanoma.

Detection of the Assembly and Disassembly of PCV2b Virus-Like Particles Using Fluorescence Spectroscopy Analysis

Monitoring the assembly and disassembly of virus-like particles (VLPs) is important in developing effective VLP-based vaccines. We tried to establish a simple and rapid method to evaluate the status of VLP assembly using fluorescence spectroscopic analysis (FSA) while developing a VLP-based vaccine against porcine circovirus type 2b (PCV2b). We synthesized the gene coding for PCV2b capsid protein (CP). The CP was expressed in Escherichia coli in a soluble form, dialyzed into three different buffers, and assembled into VLPs. The immunogenicity of the VLPs was evaluated by an enzyme-linked immunosorbent assay using the sera of mice immunized with inactivated PCV2b. The VLP assembly was detected using transmission electron microscopy and FSA. The assembled VLPs showed a distinct FSA curve with a peak at 320 nm. We found that the assembly status was related to the immunogenicity, fluorescence intensity, and morphology of the VLP. The FSA assay was able to monitor the various denatured statuses of PCV2b VLPs treated with β-mercaptoethanol or β-mercaptoethanol plus urea. We have demonstrated that FSA can be used to detect the assembly of PCV2b VLPs produced in E. coli. This provides a simple solution for monitoring VLP assembly during the production of VLP-based vaccines.

Correlation between efficacy and structure of recombinant epitope vaccines against bovine type O foot and mouth disease virus

To develop recombinant epitope vaccines against foot-and-mouth disease virus (FMDV), genes coding for six recombinant proteins (rP1–rP6) consisting of different combinations of B cell and T cell epitope from VP1 capsid protein (VP1) of type O FMDV were constructed and the 3D structure of these proteins analyzed. This revealed a surface-exposed RGD sequence of B cell epitopes in all six recombinant proteins as that in VP1 of FMDV and rP1, rP2 and rP4 globally mimicked the backbone conformation of the VP1. rP1, rP2 and rP4 stimulated guinea pigs to produce higher level of neutralizing antibodies capable of protecting suckling mice against FMDV challenge. rP1 stimulated cattle to produce FMDV-neutralizing antibody. The data suggest that an efficient recombinant epitope vaccine against FMDV should share local similarities with the natural VP1 of FMDV.

The therapeutic potency of HSP65-GTL in GL261 glioma-bearing mice.

Gliomas are the most common type of brain tumor with poor prognosis. Even after combination treatments including surgery, radiation, and chemotherapy, the median survival is around 15 months, calling for novel approaches such as immunotherapy. To develop novel therapeutic approaches, we tried to prepare a candidate vaccine by mixing the recombinant mycobacterial heat-shock protein 65 (HSP65) with GL261 glioma tissue lysate (GTL). Our data showed that HSP65-GTL induced potent cytotoxic T lymphocyte and prolonged the survival of mice bearing GL261 gliomas. Furthermore, HSP65 or HSP65-GTL upregulated mRNA expressions of ROR&ggr;t and interleukin-17A in spleen cells or draining lymph node cells, respectively, and enhanced the ratios of brain-infiltrating Th17 cells and inflammatory cells, indicating that the antitumor effect of HSP65-GTL was associated with Th17-type immunity.

Single immunization with a recombinant multiple-epitope protein induced protection against FMDV type Asia 1 in cattle

To develop recombinant epitope vaccines against the foot-and-mouth disease virus (FMDV) serotype Asia 1, genes encoding six recombinant proteins (A1-A6) consisting of different combinations of B-cell and T-cell epitopes from VP1 capsid protein (VP1) of FMDV were constructed. These proteins were expressed in Escherichia coli and used to immunize animals. Our results showed that A6 elicited higher titers of neutralizing antibodies after single inoculation in guinea pigs than did the other five recombinant proteins, as determined by micro-neutralization tests. In addition, a strong lymphocyte proliferation response and Th1 type immunity were observed in splenocytes from the mice immunized with A6. Further tests carried out in cattle demonstrated that a single inoculation with A6 generated comparable levels of neutralizing antibodies as inactivated vaccine and protected 4 of 5 cattle against challenge with FMDV type Asia 1. Our results suggest that A6 might be a promising recombinant vaccine against FMDV type Asia 1 in cattle.

Influence of hydrophilic amino acids and GC-content on expression of recombinant proteins used in vaccines against foot-and-mouth disease virus in Escherichia coli

Epitope-based protein expression in Escherichia coli can be improved by adjusting its amino acid composition and encoding genes. To that end, we analyzed 24 recombinant epitope proteins (rEPs) that carry multiple epitopes derived from VP1 protein of foot-and-mouth disease virus. High level expression of the rEPs was attributed to a high content of Arg, Asn, Asp and Thr, a low content of Gln, Pro and Lys, a high content of hydrophilic amino acids and a higher isoelectric point value resulting from abundant Arg. It is also attributed to the appropriate guanine and cytosine content in the encoding genes. The data provide a reference for adjusting the amino acid composition in designing epitope-based proteins used in vaccines and for adjusting the synonymous codons to improve their expressions in E. coli.

Effect of prophylactically applied CpG ODN on the development of myocarditis in mice infected with Coxsackievirus B3.

Coxsackievirus B3 was one of the major pathogens causing viral myocarditis. Toll-like receptor 9 activation contributed to the innate immune response in the process of CVB3-induced myocarditis. In order to find out how CpG oligodeoxynucleotide, known as a TLR-9 agonist, would affect the CVB3-induced myocarditis, we chose a C-type CpG oligodeoxynucleotide (YW002) injected to the mice one day before CVB3 challenge. On day 4 post CVB3 infection, 3 mice in each group were randomly sacrificed and their hearts were isolated to detect CVB3 replication. On day 10, the CVB3 neutralizing antibody and inflammatory change of the hearts were detected. The results indicated that the CVB3-induced myocarditis was aggravated with the declining body weight of mice, decreasing neutralizing antibody, and uncontrolling virus replication by injecting 20 μg YW002 per mouse. When adjusted the amount at 10 μg YW002 per mouse, there were no signs of aggravation in myocarditis. Plus, the mortality of the infected mice was reduced, the neutralizing antibody level was raised and the replication of virus was restrained. These results suggested that a proper amount of CpG oligodeoxynucleotide application could help to inhibit CVB3 infection.

Purification of clinical-grade recombinant HSP65-MUC1 fusion protein

HSP65‐MUC1 is a fusion protein between BCG (Bacille Calmette‐Guerin)‐derived HSP65 (heat‐shock protein 65) and human MUC1 (mucin 1) VNTR (variable number of tandem repeats)‐domain peptides that has shown antitumour efficacy. Chinas Food and Drug Administration has recently approved a Phase I clinical trial using HSP65‐MUC1 for the treatment of MUC1‐positive breast cancer. In order to produce sufficient quantities of clinical‐grade HSP65‐MUC1, we established a pilot‐scale purification scheme comprising two steps of column chromatography: HIC (hydrophobic‐interaction chromatography) and IEX (ion‐exchange chromatography). The pH values of the buffers used in homogenization and HIC were adjusted to pH 9.0 to maintain protein stability and prevent protein degradation. Using this manufacturing process, we obtained clinical‐grade HSP65‐MUC1 with a yield of 400 mg per 70 g of wet cell pellet and >96% purity.