Tosh C, Venkataramanan R, Pattnaik B, Hemadri D, Sanyal A
Central Laboratory, All India Coordinated Research Project on Foot-and-Mouth Disease, Indian Veterinary Research Institute, Mukteswar-Kumaon, Nainital, India.
Acta Virol. 1999 Aug;43(4):219-25.
A set of five neutralizing monoclonal antibodies (MAbs) to an Indian strain (IND17/77) of type A (subtype A22) foot-and-mouth disease (FMD) virus (FMDV) was used in the study. Four of the MAbs (27S, 37S, 85S, and 143S) identified a trypsin-sensitive (TS) epitope(s) and were specific for VP1, while the remaining MAb (145S) reacted with a trypsin-resistant (TR) epitope and was specific for VP3 in Western blot analysis. Both the epitopes (TS and TR) were conformation-independent in nature. Results obtained in MAb-competition enzyme-linked immunosorbent assay (ELISA), and profiling of the (MAb) neutralization-escape mutants in ELISA and cross-neutralization test revealed two overlapping TS epitopes (27S/37S and 85S/143S) on the virus. Variation at both these epitopes was observed in some field isolates of serotype A. Comparison of deduced amino acid sequence in the VP1 region (aa 140-213) between the parent virus and the mutants identified Gly148 and Arg153 as critical for the formation of both the TS epitopes. Substitution of R153 by Gly or Ser was observed in mutants with no reactivity for the MAbs 85S/143S. However, these mutants maintained partial reactivity with MAbs 27S/37S, and substitution of Gly148 by Glu eliminated both the epitopes. No amino acid substitution was observed in the VP1 region of aa 200-213. Efficient neutralization of the MAb neutralization escape mutants (MAb-resistant (MAR) mutants) by bovine vaccinate serum (BVS) indicated involvement of other epitopes on the virion surface in eliciting neutralizing antibodies following vaccination.
本研究使用了一组针对A22亚型口蹄疫病毒（FMDV）印度毒株（IND17/77）的五种中和单克隆抗体（MAb）。其中四种MAb（27S、37S、85S和143S）识别出一个胰蛋白酶敏感（TS）表位，且对VP1具有特异性，而其余的MAb（145S）在蛋白质免疫印迹分析中与一个胰蛋白酶抗性（TR）表位反应，且对VP3具有特异性。这两个表位（TS和TR）本质上均不依赖构象。在MAb竞争酶联免疫吸附测定（ELISA）中获得的结果，以及在ELISA和交叉中和试验中对（MAb）中和逃逸突变体的分析，揭示了病毒上两个重叠的TS表位（27S/37S和85S/143S）。在A型血清型的一些野毒株中观察到这两个表位的变异。亲本病毒与突变体之间VP1区域（第140 - 213位氨基酸）推导氨基酸序列的比较，确定Gly148和Arg153对两个TS表位的形成至关重要。在对MAb 85S/143S无反应性的突变体中观察到R153被Gly或Ser取代。然而，这些突变体与MAb 27S/37S仍保持部分反应性，且Glu取代Gly148消除了这两个表位。在第200 - 213位氨基酸的VP1区域未观察到氨基酸取代。牛接种疫苗血清（BVS）对MAb中和逃逸突变体（抗MAb（MAR）突变体）的有效中和表明，病毒粒子表面的其他表位参与了疫苗接种后诱导中和抗体的过程。
