乳清蛋白是动物乳中的一种优质蛋白质,具有丰富的营养价值和独特的生理功能.天然乳清蛋白性质极不稳定,为使乳清蛋白得到高效利用,衍生出许多各具特色的改性方法.本文综述了利用物理方法、生物方法、化学方法及新技术改性乳清蛋白的研究进展.物理方法主要包括热处理、高压处理、微波辐照处理、超声处理、超临界二氧化碳流体处理和低温等离子体处理等;生物方法主要包括酶法水解和酶法交联处理两种;化学方法包括磷酸化、糖基化、酰化、去酰胺、酸调处理等.此外,本文总结了不同改性方法的作用机制及其对乳清蛋白性质的影响,同时展望了乳清蛋白改性技术的应用及发展趋势.

为评价佐剂对金黄色葡萄球菌(S.aureus) CP8-FnBPB-ClfA免疫效果的影响,用纯化的S.aureus血清8型荚膜多糖与FnBPB-ClfA蛋白偶联的偶联物配合不同佐剂对健康成年新西兰大耳白母兔进行免疫接种,第1、2、3、4组的佐剂分别为弗氏佐剂、铝盐佐剂、脂质体佐剂及大肠杆菌不耐热肠毒素B(LTB),第5组为对照组用PBS免疫.用间接ELISA法和Western blot对各组兔血清中的抗体进行监测,评价体液免疫效果;通过检测Th1/Th2类细胞因子含量变化评价机体免疫被激活的程度;T淋巴细胞增殖试验评价细胞免疫,并对三免后2周的白兔进行攻毒保护试验.结果显示,以脂质体为佐剂的组7d时开始产生抗体,为产生抗体最早组,14d后抗体水平就开始下降;以LTB为佐剂的组抗体水平最高,持续时间最长.细胞免疫水平检测结果显示,经ConA刺激后,各组T淋巴细胞普遍增殖,无显著差异,刺激指数都在1.0左右;用抗原刺激的组中,以LTB为佐剂的组T淋巴细胞增殖能力最强,刺激指数为2.23,对白兔的攻毒保护率为80％.

为评价金黄色葡萄球菌黏附素蛋白FnBPA A和FnBPA D基因表达产物的免疫原性,分别用纯化的重组原核表达蛋白FnBPA A和FnBPA D免疫新西兰白兔,通过ELISA方法检测免疫家兔血清的抗体效价,用双抗体夹心法检测细胞因子的表达水平及进行全血调理吞噬试验。结果显示,在三免后第7天抗体水平分别可达1∶12 800（FnBPA A）、1∶25 600（FnBPA D）,并且FnBPA A免疫组的全血杀菌能力优于FnBPA D免疫组;同时,两者均能提高家兔体内IL-2、IL-4、IL-10和IFN-γ的表达水平,且FnBPA D组显著高于FnBPA A组（P＜0.05）。结果表明,FnBPA D基因较FnBPA A基因更适合作为奶牛乳腺炎金黄色葡萄球菌基因工程亚单位疫苗的候选基因。

On the basis of this chemical method,we chose ADH as bridge,EDC as the couplant to bide purified CP and purified ClfA-FnBPB together in order to prepare conjugates.In the couping process to determine the best mass ratio and coupling ratio of conjugate were determind.Then the Balb/C mice were immunized with the conjugates,ELISA method and mouse toxicity test were chosen to detect antibody levels and protective effect of CP conjugates.The result showed that the conjugates were made in the CP /ClfA-FnBPB mass ratio of one to two through chemical method and the coupling ratio was 1 to 1.89.Using ELISA method,7 days after the second immunity,conjugate group showed immunogenicity,and antibody titers can up to 1∶6 400.The antibody levels did not appear in negative control group and CP group.It can stimulate immune response in fusion protein group after the second immunization,but the effect was not obvious,andantibody titers is only 1∶100.The results of mouse toxicity test showed that the conjugate group had the highest survival rate,it can reach 80%.The survival rate of negative control group,CP group and fusion protein group were 20%,30% and 60%,respectively.