Prediction and identification of B cell epitopes of lactate dehydrogenase of Echinococcus granulosus

Abstract

Abstract:

Objective To predict and identify B cell epitopes of lactate dehydrogenase of Echinococcus granulosus(EgLDH), in order to advance the development of highly specific and sensitive diagnostic method for echinococcosis.Methods ESPript 3.0 online program and IEDB software was used to predict secondary structure, β-fold, Emini Surface Accessibility, Karplus & Schulz Flexibility, Kolaskar & Tongaonkar Antigenicity, Parker Hydrophilicity and Bepipred Linear Epitope of EgLDH.Based on the prediction, potential epitopes were synthesized in vitro to assess their diagnostic efficacy using ELISA.The sensitivity, specificity and cross-reactivity were evaluated using sera from patients with echinococcosis, cysticercosis and healthy participants.Cystic fluid antigen was the control.Results The predicted secondary structure of EgLDH was composed of 37.16% α-helix, 9.67% β-fold and 53.17% random coil, with four transmembrane domains.Seven potential B cell epitopes were predicted, of which four were synthesized, i.e.peptides PP-1（215-228）, PP-2 （189-200）, PP-4 （79-89） and PP-7 （21-33）, with a sensitivity of 52.9%（18/34）, 61.8%（21/34）, 82.3%（28/34） and 50.0%（17/34）, respectively, to sera from patients with echinococcosis.There were significant differences between PP-4 and PP-1, PP-2 as well as PP-7（χ² = 8.100, 5.143, 9.091, P < 0.05）.The sensitivity of cystic fluid antigen was 91.1% （31/34）, which was significantly different from those of PP-1, PP-2 and PP-7 （χ² = 9.600, 5.780, 10.530, P < 0.05）, but not PP-4 （χ² = 0.444, P > 0.05）.The specificity to normal serum was 100% （21/21）, 100% （21/21）, 95% （20/21） and 95% （20/21）, respectively, all comparable to that of cystic fluid antigen （95%, 20/21）.The cross-reactivity to cysticercosis was 0, 1/10, 2/10 and 2/10, respectively, while that of the cystic fluid antigen was 5/10.Conclusion The PP-4 epitope of EgLDH B-cell shows a high sensitivity and specificity to sera from patients with echinococcosis and may be a potential diagnostic antigen for hydatid disease.

Key words: Echinococcus granulosus, Lactate dehydrogenase, Epitopes, Prediction, Diagnosis

CLC Number:

R383.3

Shuai YAN, Ping YAN, Xiao-jin MO, Bin XU, Ting ZHANG, Wei HU, Ruo-ting ZHAN, Ping YE. Prediction and identification of B cell epitopes of lactate dehydrogenase of Echinococcus granulosus[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2017, 35(6): 554-558.

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多肽段Peptides	不同类型棘球蚴病患者血清敏感性/% Sensitivity of different types of echinococcosis patients serum /%			特异性/%Specificity/%	交叉反应性 Cross-reactivity
多肽段Peptides	囊型 Cystic echinococcosis	泡型 Alveolar echinococcosis	合计 Total	特异性/%Specificity/%	交叉反应性 Cross-reactivity
PP-1	58.8(10/17)	47.1(8/17)	52.9(18/34)	100(21/21)	0
PP-2	47.1(8/17)	76.5(13/17)	61.8(21/34)	100(21/21)	1/10
PP-4	76.5(13/17)	88.2(15/17)	82.3(28/34)^a	95(20/21)	2/10
PP-7	47.1(8/17)	52.9(9/17)	50.0(17/34)	95(20/21)	2/10
囊液抗原 Cystic fluid antigen	100 (17/17)	82.3(14/17)	91.1(31/34)	95(20/21)	5/10