【摘要】 将两种自行构建的表达人溶菌酶基因的重组质粒注射到患病奶牛的乳腺,经CMT试验证明对临床型和隐性乳房炎具有治疗作用。将其中的p205C3LYZ注射入奶牛乳腺,经微球菌溶解试验证明溶菌酶的表达量达到1 18μg/ml以上,表达至少维持8d。不同注射次数、剂量和途径的试验结果表明,重组质粒的治疗作用具有剂量和次数依赖性,3次注射450μg或2次注射400μg的治疗效果相当,乳房基部注射的治疗效果优于乳池注射。以CMT结果为主要指标的对比治疗试验结果表明,重组质粒对隐性奶牛乳房炎的治疗效果与青链霉素合剂接近,有效率分别为19/22(86 4%)和8/9(88 9%),优于中药乳炎消的治疗效果(9/13,69 2%)。3种药物治疗后,奶样中的细菌总数及葡萄球菌、链球菌和大肠杆菌等代表性致病菌的数量有明显下降,重组质粒和抗菌素治疗组的奶产量上升幅度高于中药治疗组。结果表明,表达人溶菌酶基因的重组质粒对奶牛乳房炎具有可靠、持久的治疗效果,可以代替抗菌素使用。更多还原

【Abstract】 To test the possibility of gene therapy for treating dairy cow mastitis,two eukaryotic expression vectors harboring human lysozyme(hLYZ) cDNA,called pTLYZ and p205C3LYZ,were injected into milk pools of the mammary gland with mastitis and their effectiveness was demonstrated by CMT assay.The further studies were carried out with p205C3LYZ.The hLYZ activity was detected in the milk samples from the plasmid- injected mammary glands using micrococcoal lysis assay with an expression level of>1.18 μg/mL,which maintained for at least 8 days.The treatments were dose and injection time- dependent,with a similar effectiveness between three injections of 450 μg and two injections of 400 μg of p205C3LYZ.Comparative experiments showed that the recombinant plasmid and combined antibiotics treatment had an effectiveness of 86.4%(19/22) and 88.9%(8/9),respectively,both of which were significantly higher than that of a preparation of Chinese herbs (Ruyanxiao).After the treatments,total bacterial numbers,as well as representative causative bacterial numbers(staphylococcus,streptococcus and E.coli),of the milk samples decreased and the milk yields increased significantly.These data demonstrate that the recombinant plasmid containing hLYZ cDNA can be used as an alternative drug for treating dairy cow mastitis.更多还原