請用此 Handle URI 來引用此文件：
Studies on the stability and expression characteristics of surface protein "X" on Streptococcus agalactiae
Yang, Chen Shan
|摘要:||中文摘要 無乳鏈球菌(Streptococcus agalactiae)是引起牛乳房炎的
分子量約為100 kDa。 藉由抗X蛋白血清，以 ELISA法測試X蛋白的
％CO2環境下，細菌X蛋白的表現顯著增加；(4)在pH 8、以 casein取代
Streptococcus agalactiae (SA), which was often isolated from bovine mammary gland, is one of the major pathogens causing bovine mastitis. In order to study the optimum expression conditions and the stability of surface protein "X" on SA, we at inital step isolated it by employing hot-acid extraction method followed with the FPLC purification. A protein with molecular weight of ca. 100 kDa was then identified as "X" protein by a SDS-PAGE analysis.Serum containing antibody against "X" protein (Anti-"X" serum)was obtained by immunization of rabbit with the purified "X" protein. By employing the anti-"X" serum, an ELISA protocol capable of detecting the concentration of X protein on the surface of SA was successfullly developed.Studies on the expression of "X" protein with the developed ELISA protocol revealed that :(1). different amounts of X protein was expressed on various SA strains (i.e., X type, Ic/X type, and Ia/X type), (2). SA grown under different conditions such as at 28℃, pH6, shaking, and added with 5 % bovine serum expressed nearly the same amount of "X" protein as under normal conditions (i.e., 37℃, pH 6.7, semi-anaerobically), (3). a significant increase of "X" protein was detected on SA grown under 5 % CO2 atmosphere, (4). SA grown under pH 8 or substitution of the peptone ingredient in the Todd-Hewitt medium (TH medium) with casein had expressed significantly less amount of X protein , (5). decline of X protein expression at the lag phase of SA culture were also found on the growth conditions including substitution of dextrose with lactose and addition of 5% whey in the TH medium.With regard to the stability of "X" protein , following results were obtained : (1).conditions including (a) storge at 4℃ for 32 days, and (b) repeated freeze and thaw didn't cause the decline of "X" protein titer, (2) conditions including storage at (a) -70℃for 120 days, (b)-20℃ for 60 days, (c) 25℃ for 16 days, (d) 37℃for 13 days, (e) 45℃ for one day, and (f) 63℃ instantly were found to have a significant decline effect on "X" protein titer, (3). SA culture treated with trypsin also cause the loss of "X" protein titer."X" type SA have been found to be a dominant serotype among bovine-origin SA isolates. Recently, "X" protein was even identified as an excellent target for opsonin and was capable of causing immune response in cattle. Studies of optimum expression condition as well asthe stability of "X" protein in this report may aid in providing some information for the future development of bovine mastitis vaccine.
在 DSpace 系統中的文件，除了特別指名其著作權條款之外，均受到著作權保護，並且保留所有的權利。