Development of an indirect ELISA for the identification of African swine fever virus wild-type strains and CD2v-deleted strains

Wenting Jiang; Dawei Jiang; Lu Li; Bo Wan; Jiabin Wang; Panpan Wang; Xuejian Shi; Qi Zhao; Jinxing Song; Zixiang Zhu; Pengchao Ji; Gaiping Zhang

doi:10.3389/fvets.2022.1006895

Development of an indirect ELISA for the identification of African swine fever virus wild-type strains and CD2v-deleted strains

Front Vet Sci. 2022 Sep 8:9:1006895. doi: 10.3389/fvets.2022.1006895. eCollection 2022.

Authors

Wenting Jiang^{1

2}, Dawei Jiang^{1

2

3}, Lu Li^{1

2}, Bo Wan^{1

2

4}, Jiabin Wang^{1

2}, Panpan Wang^{1

2}, Xuejian Shi^{1

2}, Qi Zhao^{1

2}, Jinxing Song^{1

2}, Zixiang Zhu^{5

6}, Pengchao Ji^{1

2

4}, Gaiping Zhang^{1

2

3

4}

Affiliations

¹ College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
² International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
³ Longhu Laboratory, Zhengzhou, China.
⁴ Henan Engineering Laboratory of Animal Biological Products, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
⁵ State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, College of Veterinary Medicine, Lanzhou University, Chinese Academy of Agricultural Sciences, Lanzhou, China.
⁶ African Swine Fever Regional Laboratory of China, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China.

Abstract

African swine fever (ASF) is a potent infectious disease with detrimental effects on the global swine industry and no currently vaccine available. The emergence of low-virulence CD2v-deleted mutants manifested as non-hemadsorption (non-HAD) strains represents a significant challenge to the prevention and control of ASF. In this study, we aimed to establish an indirect ELISA (IELISA) method for the identification of ASFV wild-type and CD2v-deleted strains. We integrated the CD2v protein extracellular domain sequence (CD2v-Ex, 1-588 bp) of the highly pathogenic strain China/2018/AnhuiXCGQ into the genome of suspension culture-adapted Chinese hamster Ovary-S (CHO-S) cells using lentivirus vectors (LVs). By screening, we identified a monoclonal CHO-S cell line that stably expressed secretory CD2v-Ex Protein. We then used the purified CD2v-Ex Protein as the detection antigen to establish an indirect ELISA method (CD2v-IELISA) for identification of the ASFV wild-type and CD2v-Deleted (CD2v^-) strains. The CD2v-IELISA method showed excellent specificity with no cross-reaction with serum samples infected with ASFV (CD2v^-), porcine reproductive and respiratory syndrome virus (PRRSV), classical swine fever virus (CSFV), porcine circovirus (PCV), porcine pseudorabies virus (PRV), swine foot and mouth disease virus (FMDV) and porcine epidemic diarrhea virus (PEDV). Furthermore, this method showed high sensitivity, allowing identification of ASFV-infected clinical serum samples up to a dilution of 1:2,560. The coefficient of variation both in and between batches was <10% with good reproducibility and a high compliance rate of 99.4%. This CD2v-IELISA method developed here is of great significance for the prevention, control and purification of ASFV.

Keywords: ASFV; CD2v extracellular fragment; CD2v-deleted; CHO cell line; identification; indirect ELISA.