Kovačević-Filipović Milica, Ilić Vesna, Vujčić Zoran, Dojnov Biljana, Stevanov-Pavlović Marija, Mijačević Zora, Božić Tatjana
Faculty of Veterinary Medicine, University of Belgrade, Bulevar Oslobodjenja 18, Belgrade, Serbia.
Vet Immunol Immunopathol. 2012 Jan 15;145(1-2):120-8. doi: 10.1016/j.vetimm.2011.10.015. Epub 2011 Nov 3.
Serum amyloid A proteins (SAA) are very sensitive acute phase proteins, displaying multiple isoforms in plasma and different body fluids. They are currently under investigation as biomarkers of diseases. The aim of the present study was to compare the concentration and isoform expression of SAA in serum and milk of cows with bacteriologically negative milk (control group) and naturally occurring Staphylococcus aureus (S. aureus) subclinical mastitis (subclinical mastitis group). Somatic cell count (SCC) and bacteriological analyses were performed to establish the control and subclinical mastitis group. SAA concentration was evaluated using a commercial ELISA kit, while expression of different isoforms (serum A-SAA and milk M-SAA3 isoforms) was visualized by denaturing isoelectrical focusing and immunoblotting. The SAA concentrations in sera and milk of cows in the subclinical mastitis group were three and 100 times higher than in those from the control group of cows, respectively. Cows in the subclinical mastitis group had more acidic SAA isoforms in serum with the most prominent one at pI 5.5. This isoform was not detected in sera from the control group. Milk samples in the subclinical mastitis group contained abundant highly alkaline M-SAA3 isoforms and most of the serum isoforms, except for that at pI 5.5. In the subclinical mastitis group SAA isoforms with equivalent pI as serum isoforms accounted for 20% of the total SAA concentration in milk. There were significant differences in the concentrations and isoform patterns of SAA in serum and milk between the control and subclinical mastitis groups of cows. Also, we demonstrated that serum SAA isoforms were not transferred to milk proportion to their plasma content.
血清淀粉样蛋白A（SAA）是非常敏感的急性期蛋白，在血浆和不同体液中呈现多种异构体。它们目前作为疾病的生物标志物正在研究中。本研究的目的是比较患有细菌学阴性乳（对照组）和自然发生金黄色葡萄球菌（S. aureus）亚临床乳腺炎（亚临床乳腺炎组）的奶牛血清和乳汁中SAA的浓度及异构体表达。进行体细胞计数（SCC）和细菌学分析以确定对照组和亚临床乳腺炎组。使用商业ELISA试剂盒评估SAA浓度，同时通过变性等电聚焦和免疫印迹观察不同异构体（血清A - SAA和乳汁M - SAA3异构体）的表达。亚临床乳腺炎组奶牛血清和乳汁中的SAA浓度分别比对照组奶牛高3倍和100倍。亚临床乳腺炎组奶牛血清中具有更多酸性SAA异构体，最突出的一种在pI 5.5。对照组血清中未检测到这种异构体。亚临床乳腺炎组的乳汁样本含有丰富的高碱性M - SAA3异构体和大多数血清异构体，但pI 5.5的异构体除外。在亚临床乳腺炎组中，与血清异构体pI相同的SAA异构体占乳汁中总SAA浓度的20%。对照组和亚临床乳腺炎组奶牛血清和乳汁中SAA的浓度及异构体模式存在显著差异。此外，我们证明血清SAA异构体不会按其血浆含量比例转移到乳汁中。
