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發問時間: 社會與文化語言 · 1 0 年前


Bacillus anthracis is a spore-forming, gram-positive bacterium

that causes anthrax. Upon entry through the skin, ingestion,

or inhalation, B. anthracis spores germinate into vegetative

bacteria. A tripartite exotoxin secreted from the bacteria

represents a key virulence factor in anthrax. The protective

antigen (PA) component of the exotoxin mediates the host cell

entry of the two other components, the lethal factor (LF), a

zinc metalloprotease that cleaves several mitogen-activated

protein kinase kinases, and the edema factor, a calmodulindependent

adenylate cyclase. Recently, the structures of all

three proteins have been determined . In addition,

the mechanisms by which the PA-LF complex (lethal

toxin [LeTx]) enters the cell have been identified along

with the chronology with which these events occur . The

protective antigen binds to two cell surface receptors, ATR

and CMG2 . The CMG2 gene is likely to be expressed in

most human tissues , and, recently, the ATR/TEM8

gene was reported to be highly expressed in epithelial cells .

The anthrax attacks of October 2001 heightened awareness

concerning the necessity of effective countermeasures for inhalation

anthrax exposure. A high anti-PA antibody titer has

been correlated with protection in guinea pigs and rabbits

immunized with the Anthrax Vaccine Adsorbed vaccine . Partial prophylaxis of animals treated with anti-PA rabbit

polyclonal antibodies was demonstrated in a guinea pig spore

challenge . Several murine monoclonal antibodies with moderate

affinities towards PA failed to show protection in the same

study, although one monoclonal antibody did show a significant

increase in the time to death (TTD) of treated animals . The

detailed mechanism of protection by anti-PA antibodies remains

a subject of intense study .



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1 個解答

  • 沁心
    Lv 4
    1 0 年前

    sorry....因為不是本科系 所以不懂spore challenge

    也搜尋不到相關的資料 所以就沒有翻譯


    已盡力的將原文翻譯出來 ...


    如果尚有翻譯不通的地方 尚請見諒

    炭疽熱是由Bacillus anthracis(炭疽桿菌)所造成,是一種會形成孢子的格蘭氏陽性菌。炭疽桿菌的孢子經由皮膚、攝入或吸入的方式進入之後,會立即形成細菌繁殖體。此一細菌所分泌的三方外毒素(tripartite exotoxin)為炭疽熱毒性的關鍵因子。此毒素中的保護性抗原(protective antigen)成分能使另外兩種成分: 致命因子(LF)與水腫因子(OF)進入宿主細胞。致命因子(LF)是一種需鋅的金屬蛋白酶,能切除好幾種絲裂原活化蛋白激酶激酶(mitogen-activated protein kinase kinases)。而水腫因子(OF)則是一種調鈣蛋白依賴的腺甘酸環化酶(calmodulin-dependent adenylate cyclase)。近日,這三種蛋白質的結構都已經確定。除此以外,保護性抗原與致命因子的複合體(致命毒素)進入細胞的途徑機制及其機制發生的先後順序也已確立。保護性抗原會與ATR與CMG2兩個細胞表面受體結合。CMG2基因可能會在人體內大多數的組織中表現,而且最近也指出,ATR/TEM8基因會在表皮細胞上大量表現。2001年十月的炭疽熱攻擊事件顯示應加強針對吸入性炭疽病暴露的有效反制措施的必要性。高濃度的抗保護性抗原抗體與已使用炭疽疫苗免疫化過的天竺鼠與兔子所產生的保護作用具有關聯性。在一些利用抗保護性抗原的兔子單株抗體而處理過的spore challenge的天竺鼠被證明有局部預防的作用。而幾種與保護性抗原有親合性的老鼠單株抗體,在處理過後,並沒有出現上述的保護作用,但單株抗體處理過的老鼠,其死亡時間有明顯延後的跡象。抗保護性抗原抗體產生保護作用的詳細機制仍是未來認真努力研究的課題。

    參考資料: 自己
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