A synthetic gonadotropin-releasing hormone (GnRH) vaccine for control of fertility and hormone dependent diseases without any adjuvant.

Active immunization against self-peptides have gained widespread acceptance inspite of their low immunogenicity. Recent applications involving multiple copies of self-peptides in linear alignment and conjugation with carrier proteins appear to increase the immune response against self-peptides. As with most vaccines, however, immunogens require supplementation with adjuvants to elicit an optimum immune response. In the present study, we prepared a double-chain mini-protein with each chain containing three linear repeats of the self-peptide gonadotropin-releasing hormone (GnRH3), the hinge region of human IgG1 (hinge), and a T-helper epitope from the measles virus protein (MVP). The GnRH3-hinge-MVP mini-protein was conjugated to purified recombinant heat shock protein 65 (Hsp 65) of Mycobacterium bovis and used to immunize rats primed with subcutaneous injections of Bacillus Calmette-Guerin (BCG) in the absence of adjuvants. The GnRH3-hinge-MVP-Hsp 65 stimulated the production of specific anti-GnRH antibodies in the absence of adjuvants and the antibody titer was comparable to that produced in rats immunized with the dimeric mini-protein in the presence of Freund's adjuvant. Moreover, immunization with the adjuvant-free GnRH3-hinge-MVP-Hsp 65 induced degeneration of the reproductive organs in both male and female rats unlike those immunized in the absence of Hsp 65 or in control animals inoculated with the vehicle only. Histological examination of the affected organs showed atrophy of the seminiferous tubules with diminished spermatogenesis in the testes of male rats. In female rats, the uteri were much smaller in size and the ovaries exhibited reduced follicular development. These findings demonstrated that GnRH3-hinge-MVP-Hsp 65 mounted a strong immune response in the absence of conventional adjuvants, and could prove useful in control of fertility and the treatment of conditions/diseases where GnRH ablation is required.

Expression and Purification of Hi-lys Peptide,a Recombinant Relevant to Hirudin / 中国生物化学与分子生物学报

A new fusion expression vector, pED-P8-Hi-lys was designed and constructed. It includes four parts, a 20 peptide sequence of hirudin that can maintain anticoagulant activity, the C-terminus of asparaginase as a fusion partner, basic octopeptide (KRKRKKSR) that makes the fusion partner easy to remove, and the unique acid-labile aspartyl-prolyl bond. It was transformed into E. coli BL-21 and the fusion protein (AnsB-C-P8-Hi-lys) was expressed effectively as inclusion bodies after inducing by lactose. The objective peptide Hi-lys was purified by means of cell disruption, washing, ethanol precipitation, acid hydrolysis, and DEAE-cellulose 52 column chromatography. The antithrombin activity of the purified Hi-lys peptide was about 50 ATU/mg by thrombin activity assays.

The immunogenicity of recombinant and dimeric gonadotrophin-releasing hormone vaccines incorporating a T-helper epitope and GnRH or repeated GnRH units.

In this study, we designed two linear peptides, GnRH-hinge-MVP, which consists of human gonadotrophin-releasing hormone (GnRH), hinge fragment 225-232/225'-232' of human IgG1 and a T helper peptide from measles virus protein (MVP), and GnRH3-hinge-MVP, which contains three copies of GnRH (so termed GnRH3). The DNA constructs encoding for the two peptides were fused to the C-terminal encoding sequence of asparaginase, encompassing residues 199-326, through an acid-labile aspartyl-prolyl linker. The chimeric genes were expressed at high levels in Escherichia coli. The fusion proteins were purified to approximate homogeneity by means of washing the inclusion bodies and by ethanol precipitation. The GnRH-hinge-MVP or the GnRH3-hinge-MVP was released from the fusion proteins by cleavage with hydrochloric acid and further oxidized into double-chain miniproteins after purification. Both dimeric constructs proved to be efficient immunogens. It was shown that rats immunized with the immunogens generated antibodies specific for GnRH. The dimeric GnRH3-hinge-MVP containing three copies of GnRH in each chain induced a higher titre of anti-GnRH antibodies than the GnRH-hinge-MVP, containing a single copy of GnRH in each chain. These results demonstrate that combining multicopies or single copies of peptide with hinge fragment of human IgG and T helper peptide from measles virus protein can induce anti-peptide immune responses. Our data also suggest that these methods of preparation and dimerization of the recombinant polypeptides may provide a useful strategy for other polypeptide vaccine developments.

Cloning of D-hydantoinase Gene from Pseudomonas and Its Expression in E.coli / 中国药科大学学报

AIM　The purpose is to construct D-hydantoinase genetic engineering strain for the purpose of the industrial production of D-p-hydroxyphenylglycine. METHODS　D-hydantoinase gene was created from Pseudomonas putida 9801 by PCR technique and inserted into pMD18-T vector. The recombinant plasmid was transformed into several Escherichia coli strains. The positive transformants with D-hydantoinase activity were obtained by the two step screening, digoxigenin DNA labeling in situ hybridization and D-hydantoinase activity assay. RESULTS　The D-hydantoinase activity of the genetic engineering strain E.coli BL21/pMD-dht was 1700 U*L-1 and increased as high as 8 times compared with those of wild-type strain Pseudomonas putida 9801. The subunit molecular weight of recombinant D-hydantoinase was about 53 kDa measured by SDS-PAGE. The amount of the recombinant D-hydantoinase was about 20 percent of total bacterial soluble proteins. CONCLUSION　The genetic engineering strain E.coli BL21/pMD-dht possesses the initial industrial production prospects.

Optimization of liquid culture conditions of dihydropyrimidinase producing strain Pseudomonas putida 9801 / 中国生化药物杂志

Purpose　The aim is to optimize the liquid culture conditions of dihydropyrimidinase producing strain Pseudomonas putida 9801. Methods　Plackett-Burman design and spherical symmetric desig n were used.Results　Optimum conditions for dihydropyrimidinas e formation of Pseudomonas putida 9801 were defined:yeast extract 2.39%, Glu cose 1.81%,Uracil 0.06%,K2HPO4*3H2O 0.2%, MgCl2*6H2O 0.05%and NaCl 0 .3%,when the strain was cultured at 32℃ for 10 h,about 3.02 units/ml of hydanto inase was obtained. This value was quite consistent with the theory value(2.91 u nits/ml).Conclusion　The liquid culture conditions of dihydrop yrimidinase producing strain were optimized.