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The fluorescent treponemal antibody absorption (FTA-ABS) test is a diagnostic test for syphilis. Using antibodies specific for the ''Treponema pallidum'' species, such tests would be assumed to be more specific than non-treponemal testing such as VDRL, but have been shown repeatedly to be sensitive but not specific for the diagnosis of neurosyphilis in CSF. In addition, FTA-ABS turns positive earlier and remains positive longer than VDRL. Other treponemes, such as ''T. pertenue'', may also produce a positive FTA-ABS. The ABS suffix refers particularly to a processing step used to remove nonspecific antispirochetal antibodies present in normal serum. In general, the test has two roles: # As a confirmatory test for a positive result from a serum screening test (RPR for example). # Since the test has high negative predictive value it is very useful in both serum or CSF to exclude/rule out neurosyphilis if the FTA test result is negative. " A negative FTA in serum excludes neurosyphilis". == Procedure == The antigen for the FTA-ABS test is whole bacteria. The bacteria cannot be cultured on laboratory media, so the organisms used are a lyophilized suspension of ''T. pallidum'' extracted from rabbit testicular tissue. This is spread over and fixed to a slide. Patient serum is mixed with an absorbent (the "ABS" part of the test) containing an extract of a non-pathogenic treponeme, ''Treponema phagedenis'' biotype Rieter. The purpose of the absorbent is to remove anti-treponemal antibodies that are not specific for the syphilis bacteria. The pre-adsorbed patient serum is then added to the slide; if the patient has been infected by syphilis, their antibodies will bind to the bacteria. FITC (a fluorophore)-labeled anti-treponeme antibody and TRITC (another fluorophore)-labeled anti-human antibodies are added as secondary antibodies. The spirochete location is identified using the FITC staining and the TRITC staining identifies whether the patient has anti-T. pallidum antibodies (binding to the same spirochete). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fluorescent treponemal antibody absorption test」の詳細全文を読む スポンサード リンク
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