Levine M M, Young C R, Black R E, Takeda Y, Finkelstein R A
J Clin Microbiol. 1985 Feb;21(2):174-9. doi: 10.1128/jcm.21.2.174-179.1985.
Serum immunoglobulin G antibodies to purified heat-labile enterotoxin (LT) from human (LTh) and porcine (LTp) Escherichia coli strains and cholera enterotoxin (CT) were measured by an enzyme-linked immunosorbent assay. Sera from patients with LTh E. coli infection showed a prominent response with LTh, an intermediate response with LTp, and a meager response with CT. Of 47 persons with clinical LTh-producing E. coli (herein shortened to LTh E. coli) infections, significant rises in antitoxin were detected against LTh in 36 (77%), against LTp in 30 (64%), and against CT in only 13 (28%) patients; seroconversions also occurred in 11 of 14 (79%) patients with subclinical LTh E. coli infections. In North Americans with experimental LTh E. coli infection, anti-Lth did not remain at high levels for more than 3 months. Persons with cholera manifested antitoxin responses that were similarly potent against all three toxin antigens; in fact, net optical density values were often slightly higher against LTh than against CT. The ratio of CT/LTh ELISA net optical density in convalescent sera proved to be a sensitive means to differentiate LT E. coli from cholera infection. All 11 cholera patients tested had CT/LTh ratios of greater than 0.70, whereas in only 1 of 47 LTh E. coli infections did the ratio exceed that value (it was 0.71) (P less than 0.0000000001). In single serum specimens, a net optical density of greater than or equal to 0.30 against LTh was shown to be a useful cutoff in screening sera for recent LTh E. coli or past cholera infection. The CT/LTh ratio was then used to differentiate definitively. Sera from healthy 3- to 5-year -olds and 15- to 19-year-olds in Maryland, Chile, and Bangladesh were tested against LTh and CT. The serological results fit known epidemiological observations. (i) LTh infections are rare in the United States (only 2 of 60 sera had LTh net optical density values of >/= 0.30. (ii) In contrast, evidence of recent LTh E. coli infections was very common in Chilean (69%) and Bangladeshi (57%) 3- to 5-year-olds and not uncommon in 15- to 19-year-olds (38 and 31%, respectively) in those countries. (iii) Only Bangladeshi sera showed serological evidence of cholera infections (CT/LTh ratios of > 0.70). The immunoglobulin G enzyme-linked immunosorbent assay measuring antibodies to purified LTh and CT represents a practical and effective tool for the serological study of LTh E. coli and cholera diarrheal infections.
采用酶联免疫吸附测定法检测人源（LTh）和猪源（LTp）大肠杆菌菌株的纯化不耐热肠毒素（LT）以及霍乱肠毒素（CT）的血清免疫球蛋白G抗体。LTh大肠杆菌感染患者的血清对LTh反应显著，对LTp反应中等，对CT反应微弱。在47例临床感染产LTh大肠杆菌（以下简称为LTh大肠杆菌）的患者中，36例（77%）检测到抗毒素针对LTh显著升高，30例（64%）针对LTp显著升高，仅13例（28%）患者针对CT显著升高；14例亚临床LTh大肠杆菌感染患者中有11例（79%）也发生了血清转化。在患有实验性LTh大肠杆菌感染的北美人群中，抗Lth水平在3个月以上未维持在高水平。霍乱患者表现出对所有三种毒素抗原同样有效的抗毒素反应；事实上，针对LTh的净光密度值往往比对CT的略高。恢复期血清中CT/LTh ELISA净光密度比值被证明是区分LT大肠杆菌感染和霍乱感染的敏感方法。所有11例接受检测的霍乱患者的CT/LTh比值均大于0.70，而在47例LTh大肠杆菌感染中只有1例（比值为0.71）该比值超过此值（P小于0.0000000001）。在单份血清标本中，针对LTh的净光密度大于或等于0.30被证明是筛查近期LTh大肠杆菌感染或既往霍乱感染血清的有用临界值。然后用CT/LTh比值进行明确鉴别。对马里兰州、智利和孟加拉国3至5岁及15至19岁健康人群的血清进行LTh和CT检测。血清学结果符合已知的流行病学观察结果。（i）在美国，LTh感染很少见（60份血清中只有2份LTh净光密度值≥0.30）。（ii）相比之下，在智利（69%）和孟加拉国（57%）3至5岁儿童中，近期LTh大肠杆菌感染的证据非常常见，在这些国家15至19岁人群中也并不少见（分别为38%和31%）。（iii）只有孟加拉国的血清显示有霍乱感染的血清学证据（CT/LTh比值>0.70）。测量针对纯化LTh和CT抗体的免疫球蛋白G酶联免疫吸附测定法是LTh大肠杆菌和霍乱腹泻感染血清学研究的实用有效工具。
