中和性抗體是由血液中獲得性免疫細胞暴露于病毒后產生的一類可溶性蛋白。在血液中，它們能與病毒結合，阻止其進一步感染人體細胞，并可導致病毒顆粒裂解，引起“中和”反應。由于中和性抗體可以在病毒感染人體細胞之前將其“消滅”，因此，如果此類抗體在人體暴露于HIV之前就存在，將可以預防感染發生。只有少數HIV陽性病人在感染HIV病毒數年后能產生強效廣譜中和性抗體。動物實驗顯示，如果一種預防性疫苗能引發這些抗體，就能阻止HIV感染。PG9和PG16是科學家首次發現的強效HIV廣譜性抗體，可以與HIV-1中的一個糖蛋白(gp120)特定表位結合，阻止HIV-1感染人體細胞。由于傳統ELISA和病毒中和實驗并不能解決接種疫苗動物產生的抗體特異性。為鑒定表位特異性，Hoffenberg等在MSD的多因子微孔板內點了PG9, PGT126, PGV04, b6, 17b, and 2F5等抗體。這是基于Meso Scale Discovery (MSD)技術開發了一種競爭結合（competition-binding assay）方法，用以檢測接種疫苗后的動物血清是否含有識別表位的抗體。在Journal of Virology ，有多篇文章應用和開發Meso Scale Discovery (MSD)電化學發光技術。

 

Multiplexed competition antibody binding assay.To determine epitope specificity, we developed a competition-binding assay (CBA) based on Meso Scale Discovery (MSD) Sector Imager technology. MSD uses electrochemiluminescence (ECL) to detect binding events in a unique and sensitive manner with a _4-log dynamic range. The goal of the CBA is to determine whether sera from vaccinated animals contain Abs recognizing epitopes similar to those bound by well-characterized Env-specific Abs. The Abs PG9, PGT126, PGV04, b6, 17b, and 2F5 were each spotted onto MSD multiarrays. Dilutions of sera were preincubated for 1 h at 37°C with an excess of soluble biotinylated BG505 L111A gp120 or with a clade C gp120 chimera based on isolate 16096 with a V1 to V3 loop substitution from subtype 16055, a clade C isolate that we term 16936-V55. This mixture was then transferred to an MSD plate blocked with PBS containing 3% BSA and incubated for 1 h at room temperature. Plates were washed with PBS containing 0.02% Tween 20 before incubation with a streptavidin-Sulfo tag reporter reagent. Plates were read using the Sector Imager 2400. A reduction in signal reflects the presence of Abs in serum that competed with spotted Abs for binding to gp120. An advantage of this assay configuration is that it detects binding to soluble antigen, which may possess a more native structure compared with plate-bound antigen.

 

 

原文：Hoffenberg S, Powell R, Carpov A, Wagner D, Wilson A, Kosakovsky Pond S, Lindsay R, Arendt H, Destefano J, Phogat S, Poignard P, Fling SP, Simek M, Labranche C, Montefiori D, Wrin T, Phung P, Burton D, Koff W, King CR, Parks CL, Caulfield MJ. Identification of an HIV-1 clade A envelope that exhibits broad antigenicity and neutralization sensitivity and elicits antibodies targeting three distinct epitopes.  J Virol. 2013 May;87(10):5372-83. doi: 10.1128/JVI.02827-12. Epub 2013 Mar 6.

 

有關Meso Scale Discovery （MSD）公司：Amgen的創始人之一Sam Wohlstadter投資了MSD。美國MSD成立于1995年，在2009年全球首次檢測到人攜帶甲型H1N1病毒，在2013年被評為“全球前五的免疫分析品牌”。其研發的基于微孔板的電化學發光檢測技術（簡稱：微孔板ECL ）是全面升級/替代ELISA， Western Blot，多蛋白因子檢測的第三代免疫分析技術。已經廣泛被醫藥研發中心、藥物安全性評價中心、GLP實驗室、合同外包企業（CRO）、診斷、生物技術企業應用于藥物篩選，動物模型，藥物代謝，血藥濃度，免疫原性，中和實驗，Biomarker篩選，抗體親和力，疫苗評估，宿主細胞殘留，診斷研究。