Isolation and identification of a highly pathogenic strain of porcine epidemic diarrhea virus

Abstract

Porcine epidemic diarrhea virus (PEDV) causes acute watery diarrhea and high mortality in neonatal piglets, resulting in substantial economic losses to the global swine industry. Here, we successfully isolated a PEDV strain, designated CHN-CQ-2021, from PEDV-positive diarrheic samples collected from a pig farm in Chongqing, China. Electron microscopy observation revealed that the CHN-CQ-2021 strain exhibited typical coronavirus morphology and could be recognized by PEDV-specific antibodies. Phylogenetic analysis of its full-length genome and S gene further classified this isolate as a G2b variant strain. Importantly, 1-day-old newborn piglets were orally challenged with CHN-CQ-2021 at 2 × 10⁶ 50% tissue culture infectious dose/mL. Compared with the control group, the infected piglets developed severe diarrhea with 100% mortality. In addition, viral RNA was detected in rectal swabs and multiple tissues, including the intestinal tract and brain, with macroscopic/microscopic intestinal lesions and viral antigen distribution confirmed using histopathology and immunohistochemistry. These findings demonstrate the presence of a pathogenic PEDV strain in Chongqing, China, capable of causing severe neonatal piglets’ enteric disease.

Keywords

Porcine epidemic diarrhea virus / Isolation and identification / Pathogenicity / Newborn piglets / China

References

[1] Chen J, Cheng Z, Chen J, Qian L, Wang H, Liu Y. Advances in human norovirus research: Vaccines, genotype distribution and antiviral strategies. Virus Res. 2024;350:199486. doi: 10.1016/j.virusres.2024.199486

[2] Roach SN, Langlois RA. Intra- and cross-species transmission of astroviruses. Viruses. 2021; 13(6):1127. doi: 10.3390/v13061127

[3] Kotloff KL, Platts-Mills JA, Nasrin D, Roose A, Blackwelder WC, Levine MM. Global burden of diarrheal diseases among children in developing countries: Incidence, etiology, and insights from new molecular diagnostic techniques. Vaccine. 2017; 35(49):6783-6789. doi: 10.1016/j.vaccine.2017.07.036

[4] Abebe E, Gugsa G, Ahmed M. Review on major food-borne zoonotic bacterial pathogens. J Trop Med. 2020;2020:4674235. doi: 10.1155/2020/4674235

[5] Ghssein G, Barakat R, Nehme N, Awada R, Hassan HF. Fecal prevalence of campylobacter spp. In house dogs in lebanon: A pilot study. Vet World. 2023; 16:2250-2255. doi: 10.14202/vetworld.2023.2250-2255

[6] Awada R, Ghssein G, El Roz A, Farhat M, Nehme N, Hassan HF. Prevalence of Campylobacter spp. In broilers in north lebanon. Vet World. 2023; 16:322-328. doi: 10.14202/vetworld.2023.322-328

[7] Liu C, Dong X, Liu P, Lin X. Advances in porcine respiratory and intestinal organoids: Status and potential application for virus infections. One Health Adv. 2024; 2(1):22. doi: 10.1186/s44280-024-00052-0

[8] Zhou P, Fan H, Lan T, et al. Fatal swine acute diarrhoea syndrome caused by an hku2-related coronavirus of bat origin. Nature. 2018; 556(7700):255-258. doi: 10.1038/s41586-018-0010-9

[9] Jiao R, Ji Z, Zhu X, et al. Genome analysis of the g6p6 genotype of porcine group c rotavirus in China. Animals (Basel). 2022; 12(21):2951. doi: 10.3390/ani12212951

[10] McCluskey BJ, Haley C, Rovira A, Main R, Zhang Y, Barder S. Retrospective testing and case series study of porcine delta coronavirus in u.S. Swine herds. Prev Vet Med. 2016; 123:185-191. doi: 10.1016/j.prevetmed.2015.10.018

[11] Liu Q, Wang HY. Porcine enteric coronaviruses: An updated overview of the pathogenesis, prevalence, and diagnosis. Vet Res Commun. 2021; 45(2-3):75-86. doi: 10.1007/s11259-021-09808-0

[12] Li C, Lu H, Geng C, et al. Epidemic and evolutionary characteristics of swine enteric viruses in south-central china from 2018 to 2021. Viruses. 2022; 14(7):1420. doi: 10.3390/v14071420

[13] Fragoso-Saavedra M, Liu Q. Towards developing multistrain pedv vaccines: Integrating basic concepts and sars-cov-2 pan-sarbecovirus strategies. Virology. 2025;604:110412. doi: 10.1016/j.virol.2025.110412

[14] Lin F, Zhang H, Li L, et al. Pedv: Insights and advances into types, function, structure, and receptor recognition. Viruses. 2022; 14(8):1744. doi: 10.3390/v14081744

[15] Kocherhans RB, Bridgen A, Ackermann M, Tobler K. Completion of the porcine epidemic diarrhoea coronavirus (pedv) genome sequence. Virus Genes. 2001; 23(2):137-144. doi: 10.1023/A:1012508705001

[16] Li X, Wu Y, Yan Z, et al. A comprehensive view on the protein functions of porcine epidemic diarrhea virus. Genes (Basel). 2024; 15(2):165. doi: 10.3390/genes15020165

[17] Pensaert MB, De Bouck P. A new coronavirus-like particle associated with diarrhea in swine. Arch Virol. 1978;58:243-247. doi: 10.1007/BF01317606

[18] Song D, Park B. Porcine epidemic diarrhoea virus: A comprehensive review of molecular epidemiology, diagnosis, and vaccines. Virus Genes. 2012; 44(2):167-175. doi: 10.1007/s11262-012-0713-1

[19] Sun D, Wang X, Wei S, Chen J, Feng L. Epidemiology and vaccine of porcine epidemic diarrhea virus in china: A mini-review. J Vet Med Sci. 2016; 78(3):355-363. doi: 10.1292/jvms.15-0446

[20] Yao X, Qiao WT, Zhang YQ, et al. A new pedv strain ch/ hljjs/2022 can challenge current detection methods and vaccines. Virol J. 2023; 20(1):13. doi: 10.1186/s12985-023-01961-z

[21] Xu Z, Zhang Y, Gong L, et al. Isolation and characterization of a highly pathogenic strain of porcine enteric alphacoronavirus causing watery diarrhoea and high mortality in newborn piglets. Transbound Emerg Dis. 2018; 66(1):119-130. doi: 10.1111/tbed.12992

[22] Xu Z, Zhong H, Zhou Q, et al. A highly pathogenic strain of porcine deltacoronavirus caused watery diarrhea in newborn piglets. Virol Sin. 2018; 33(2):131-141. doi: 10.1007/s12250-018-0003-8

[23] Reed LJ, Muench H. A simple method of estimating fifty per cent endpoint. Am J Epidemiol. 1938; 27:493-497. doi: 10.1093/oxfordjournals.aje.a118408

[24] Quinting BR, Robert B, Letellier C, et al. Development of a 1-step enzyme-linked immunosorbent assay for the rapid diagnosis of bovine respiratory syncytial virus in postmortem specimens. J Vet Diagn Invest. 2007;19:238-243. doi: 10.1177/104063870701900302

[25] Bjustrom-Kraft J, Woodard K, Giménez-Lirola L, et al. Porcine epidemic diarrhea virus (pedv) detection and antibody response in commercial growing pigs. BMC Vet Res. 2016; 12(1):99. doi: 10.1186/s12917-016-0725-5

[26] Chen Q, Gauger P, Stafne M, et al. Pathogenicity and pathogenesis of a united states porcine deltacoronavirus cell culture isolate in 5-day-old neonatal piglets. Virology. 2015; 482:51-59. doi: 10.1016/j.virol.2015.03.024

[27] Madson DM, Magstadt DR, Arruda PHE, et al. Pathogenesis of porcine epidemic diarrhea virus isolate (us/ iowa/18984/2013) in 3-week-old weaned pigs. Vet Microbiol. 2014; 174(1-2):60-68. doi: 10.1016/j.vetmic.2014.09.002

[28] Huang YW, Dickerman AW, Piñeyro P, et al. Origin, evolution, and genotyping of emergent porcine epidemic diarrhea virus strains in the united states. mBio. 2013; 4(5):e00737. doi: 10.1128/mBio.00737-13

[29] Zhang F, Luo S, Gu J, et al. Prevalence and phylogenetic analysis of porcine diarrhea associated viruses in Southern China from 2012 to 2018. BMC Vet Res. 2019; 15(1):470. doi: 10.1186/s12917-019-2212-2

[30] Li W, Li H, Liu Y, et al. New variants of porcine epidemic diarrhea virus, china, 2011. Emerg Infect Dis. 2011. Emerg Infect Dis. 2012; 18(8):1350-1353. doi: 10.3201/eid1808.120002

[31] Kiesslich S, Kamen AA. Vero cell upstream bioprocess development for the production of viral vectors and vaccines. Biotechnol Adv. 2020;44:107608. doi: 10.1016/j.biotechadv.2020.107608

[32] Zhu N, Zhang D, Wang W, et al. A novel coronavirus from patients with pneumonia in china, 2019. N Engl J Med. 2020; 382(8):727-733. doi: 10.1056/NEJMoa2001017

[33] Woo PCY, Huang Y, Lau SKP, Yuen KY. Coronavirus genomics and bioinformatics analysis. Viruses. 2010; 2(8):1804-1820. doi: 10.3390/v2081803

[34] Yin L, Liu X, Hu D, Luo Y, Zhang G, Liu P. Swine enteric coronaviruses (PEDV, TGEV, and PDCoV) induce divergent interferon-stimulated gene responses and antigen presentation in porcine intestinal enteroids. Front Immunol. 2022;12:826882. doi: 10.3389/fimmu.2021.826882

[35] Yuan CZ, Zhang P, Liu P, et al. A novel pathway for porcine epidemic diarrhea virus transmission from sows to neonatal piglets mediated by colostrum. J Virol. 2022; 96(14):e0047722. doi: 10.1128/jvi.00477-22

[36] Li Q, Xu Z, Wu T, et al. A flagellin-adjuvanted ped subunit vaccine improved protective efficiency against pedv variant challenge in pigs. Vaccine. 2018; 36(29):4228-4235. doi: 10.1016/j.vaccine.2018.05.124