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The strain-specific epitopes identified on FMDV serotype A A/AF72 strain and A/GDMM/2013 strain.

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posted on 2023-11-20, 18:46 authored by Kun Li, Yong He, Li Wang, Pinghua Li, Huifang Bao, Shulun Huang, Shasha Zhou, Guoqiang Zhu, Yali Song, Ying Li, Sheng Wang, Qianliang Zhang, Pu Sun, Xingwen Bai, Zhixun Zhao, Zhiyong Lou, Yimei Cao, Zengjun Lu, Zaixin Liu

The antibody-driven variations on A/AF72 strain (A) and A/GDMM/2013 strain (B) were separately determined by selection of neutralization-escape mutants using 20 A/AF72-specific and A/GDMM/2013-specific neutralizing mAbs individually. The proportion of pin chart indicated each mAb-driven variation accounted for the five known antigen sites encompassing VP1 GH loop and C-terminus (site 1/5), VP1 B-C loop (site 3), VP2 B-C loop (site 2) and VP3 B-B knob (site 4), as well as the other unidentified site. (C) Amino acid sequence alignment of VP3 of A/AF72, A/WH/CHA/09 and A/GDMM/2013 strains. The VP3 68 and 175 positions that formed strain-specific epitopes were framed with black oval circles. (D) Immunofluorescence analysis of rescued VP3 68 (T→A) mutant that was constructed basis on entire P1 gene of A/GDMM/2013 strain. BHK-21 cells were infected with the rescue mutant or wildtype virus (A/GDMM/2013) at an MOI of 10 for 4 h. FMDV protein 3A was detected using mouse mAb 3A24 and an Alexa Fluor 561-conjugated secondary antibody. (E) The neutralization efficacy of the A/AF72-specific mAbs W3 and W72 against wildtype (A/GDMM/2013) and its mutant (VP3 T68A) was evaluated using a microneutralization assay. The neutralization concentration represents the lowest antibody required to fully prevent CPE. ** indicates a significant difference compared to wildtype at P<0.01.