Construction and identification of recombinant avian adeno-associated virus expressing GFP reporter gene / 病毒学报

To generate recombinant avian adeno-associated virus (rAAAV) for gene transfer studies in avian cells, the recombinant plasmid containing the whole genome of AAAV was digested with restriction enzymes to remove the Rep and Cap genes, resulting in AAAV transfer vector pAITR. GFP-expressing cassette was amplified by PCR and inserted into the AAAV transfer vector. The Rep-Cap gene of AAAV amplified by high fidelity PCR was subcloned into eukaryotic expression vector pcDNA3, resulting in an AAAV helper vector pcDNA-ARC. The Rep and Cap genes amplified by high fidelity PCR were subcloned separately into the co-expression vector pVITRO2-mcs, resulting in another AAAV helper vector pVITRO2-ARC. Using calcium phosphate precipitation method, rAAAV-GFP was generated by co-transfecting AAV-293 cells with a cocktail of pAITR-GFP, pcDNA-ARC or pVITRO2-ARC, and adenovirus helper vector pHelper. The three structural proteins VP1, VP2 and VP3 of correct molecular masses were detected by SDS-PAGE and the GFP reporter gene was detected by PCR in purified rAAAV-GFP virions. Chicken embryonic fibroblast (CEF) cells and CEL cell line were transduced with the recombinant virus, the GFP-positive cells were easily observed under fluorescent microscope, expression of which lasted for at least two weeks. These data demonstrate that an efficient helper virus-free packaging system has been established for generating recombinant AAAV particles for gene transfer studies in avian cells and for development of recombinant vaccines against avian diseases.

Intramammary expression and therapeutic effect of a human lysozyme-expressing vector for treating bovine mastitis / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

To develop a gene therapy strategy for treating bovine mastitis, a new mammary-specific vector containing human lysozyme (hLYZ) cDNA and kanamycin resistance gene was constructed for intramammary expression and clinical studies. After one time acupuncture or intracisternal infusion of healthy cows with 400 microg of the p215C3LYZ vector, over 2.0 microg/ml of rhLYZ could be detected by enzymatic assay for about 3 weeks in the milk samples. Western blotting showed that rhLYZ secreted into milk samples from the vector-injected cows had molecular weight similar to that of the natural hLYZ in human colostrums. Twenty days after the primary injection, the quarters were re-injected with the same vector by quarter acupuncture and even higher concentrations of rhLYZ could be detected. Indirect competitive ELISA of milk samples showed that the vector injection did not induce detectable humoral immune response against hLYZ. Clinical studies showed that twice acupuncture of quarters with the p215C3LYZ vector had overt therapeutic effect on clinical and subclinical mastitis previously treated with antibiotics, including disappearance of clinical symptoms and relatively high microbiological cure rates. These data provide a solid rationale for using the vector to develop gene therapy for treating bovine mastitis.

Transfection and expression of exogenous gene in laying hens oviduct in vitro and in vivo / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

To examine whether or not the regulatory sequence of chicken ovalbumin gene can drive transgene expression specifically in hen oviduct, the authors constructed an oviduct-specific expression vector (pOV), containing 3.0 kilobases (kb) of the 5'-flanking sequence and 3.0 kb of the 3'-flanking sequence of the chicken ovalbumin gene. Jellyfish green fluorescence protein (EGFP) reporter gene and bacterial LacZ reporter gene were respectively inserted into the downstream of the 5'-regulatory region. The recombinants were named as pOVEGFP and pOVLacZ. Two transfer systems, in vitro and in vivo, were used to verify the function of the vector. In vitro, the plasmid DNA pOVEGFP and pEGFP-N1 were transfected respectively by the polyethyleneimine procedure into the primary chicken oviduct epithelium (PCOE) and fibroblasts cells isolated from laying hens. In vivo, the recombinant vector pOVLacZ was injected into egg-laying hens via wing vein and the tissues were collected for RT-PCR analysis. The results showed that expression of pEGFP-N1 was achieved at low level in oviduct epithelial cells and at high level in fibroblasts, but that the recombinant vector was not expressed in both cells. RT-PCR analysis showed that the LacZ gene was transcribed in the oviduct, but not in the heart, liver, kidney and spleen of the injected hens. Accordingly, the beta-galactosidase activity was only detected in the oviduct magnum (116.7 mU/ml) and eggs (16.47 mU/ml). These results indicated that the cloned regulation regions of chicken ovalbumin gene could drive exogenous gene expression specifically in the oviducts of hens. In vivo gene injection via wing vein may serve as a rapid production system of recombinant proteins in chicken eggs. In addition, the cultured primary oviduct cells from laying hens were not efficient temporary expression systems for analyzing the function of regulating elements of ovalbumin gene.

Generation of transgenic mice expressing human lysozyme in mammary gland / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To evaluate the feasibility of generating animal mammary gland bioreactors expressing human lysozyme (hLYZ).</p><p><b>METHODS</b>The recombinant vector p205C3-hLYZ, as a result of connecting the hLYZ cDNA with the mammry gland expression vector p205C3, was used to generate transfer genic mice by microinjection.</p><p><b>RESULTS</b>A total of 136 F0 mice were obtained, of which 7 (2 females and 5 males) and 4 (1 females and 3 males) were found to contain the transfer-gene by PCR and Southern blotting respectively. The results of Western blotting indicated that the expressed protein had the same molecular weight as that of normal hLYZ. From the F1 generation on, the mice mated only with their brothers or sisters and a colony of F7 transgenic mice was obtained. Among the offspring, the female transgenic mice maintained and expressed the transfer-gene stably with an expression level as high as 750 mg/L. The expressed protein had strong tissue specificity, and in addition to the mammary glands, some degree of ectropic expression in the spleens and intestines of the transgenic mice was confirmed by dot blotting assay.</p><p><b>CONCLUSION</b>These data indicate that the mice mammary gland bioreactors expressing hLYZ have been successfully generated.</p>