直接和间接ELISA之间的差异

Key Difference – Direct vs Indirect ELISA

An enzyme-linked immunoassay (Elisa），也称为酶免疫测定serological测试哪些检测antibodiesin the blood.它被用作诊断工具，以找出患者是否已暴露于特定类型的病毒或另一种感染剂（抗原）以及人体是否产生了针对感染的抗体。ELISA还可以识别过去和当前infections. Hence, ELISA is often used as a prescreening test by the doctors prior to in-depth analysis of diseases. This test can be performed in the laboratory by taking a blood sample from the patient. There are two types of ELISA test: direct ELISA and indirect ELISA. The key difference between direct and indirect ELISA is that间接ELISA更敏感，需要添加二抗whiledirect ELISAis less sensitive and only uses a primary antibody.

内容
1.Overview and Key Difference
2.What is Direct ELISA
3.什么是间接ELISA
4.并排比较 - 直接与间接ELISA
5.概括

What is Direct ELISA?

ELISA是进行疾病诊断测试，以鉴定血液中特定的抗原或抗体的存在。它是作为盘子测定法完成的。它使用与易于测定的抗体enzymes. Antigens’ presence in the serum sample bind with specific antibodies linked with enzymes. In the final step, a specific substrate is added to react with the enzyme. The enzyme converts the substrate into a coloured or signal-producing product. The colour change in the chemical substrate reveals the presence of a particular antibody in the serum sample. Direct ELISA test uses only a primary antibody linked to the enzyme. Upon binding to the antigen, it quickly changes the colour, indicating the presence of the infectious agent in the blood. However, the intensity of the signals is weaker in direct ELISA since the epitopes are limited to binding of the antigens. Hence, direct ELISA is less sensitive compared to indirect ELISA.

什么是间接ELISA?

ELISA可以使用两种类型的抗体，即进行ELISA。一抗和二抗。间接ELISA工具使用两种类型的抗体来扩增信号以更好地检测。间接ELISA技术的执行如下。

1. Plates are incubated with antigens and washed to block nonspecific binding.
2. 然后添加主抗体并洗涤。
3. Enzyme-linked secondary antibody are added and washed.
4. A substrate is added and allowed to react with enzymes.
5. 检测到信号，并鉴定出样品中特定抗原的存在或不存在。

In indirect ELISA test, several secondary antibodies can bind to a single primary antibody. Secondary antibodies are linked with easily assayed enzymes. Therefore, one binding can make a strong signal due to more than one interactions. Hence, indirect ELISA is more sensitive than direct ELISA. However, indirect ELISA can make nonspecific signals due to cross reactions of the secondary antibodies.

What is the difference between Direct and Indirect ELISA?

直接与间接ELISA
直接Elisais less sensitive compared to indirect ELISA.	Indirect ELISA is more sensitive.
用的时间
直接Elisatest is a quick process.	间接ELISA耗时。
使用抗体
Only one type of antibodies (Primary antibodies) are used in direct ELISA.	Primary and secondary antibodies are used for indirect ELISA.
Link with Enzymes
Primary antibodies are linked with enzymes.	二抗与酶有关。
Cross-Reactivity of Second Antibodies
直接Elisaeliminates the cross-reactivity of second antibodies.	Indirect ELISA is affected with cross-reactivity of second antibodies.
Signals
Signals are weak compared to indirect ELISA.	Signals are amplified in indirect ELISA. Hence, it is easy to detect.

概括– Direct vs Indirect ELISA

Elisais a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a blood sample of a patient. It can be performed via two processes known as direct or indirect ELISA. Direct ELISA test uses only primary antibodies to detect the antigen while indirect ELISA uses both primary and secondary antibodies. In direct ELISA, primary antibodies are labelled whereas in indirect ELISA secondary antibodies are labelled. This is the difference between direct and indirect ELISA.

参考
1.“酶联免疫吸附测定法（ELISA）。”世界卫生组织公告。美国国家医学图书馆，1976年。2017年3月29日
2. Loon, A. M van, J. T Van Der Logt, F. W. Heessen, and J. Van Der Veen. “Enzyme-linked immunosorbent assay that uses labeled antigen for detection of immunoglobulin M and A antibodies in toxoplasmosis: comparison with indirect immunofluorescence and double-sandwich enzyme-linked immunosorbent assay.” Journal of Clinical Microbiology. U.S. National Library of Medicine, June 1983. Web. 29 Mar. 2017

Image Courtesy:
1. “ELISA diagram” By Cavitri – Own work(CC BY 3.0)viaCommons Wikimedia
2. “Indirect ELISA” By Cawang – Own work (CC0) viaCommons Wikimedia