{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T23:36:02Z","timestamp":1790206562685,"version":"4.1.0"},"reference-count":36,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2019,10,22]],"date-time":"2019-10-22T00:00:00Z","timestamp":1571702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2018YFD0500106"],"award-info":[{"award-number":["2018YFD0500106"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Some coronaviruses (CoVs) have an extra furin cleavage site (RRKR\/S, furin-S2\u2032 site) upstream of the fusion peptide in the spike protein, which plays roles in virion adsorption and fusion. Mutation of the S2\u2032 site of QX genotype (QX-type) infectious bronchitis virus (IBV) spike protein (S) in a recombinant virus background results in higher pathogenicity, pronounced neural symptoms and neurotropism when compared with conditions in wild-type IBV (WT-IBV) infected chickens. In this study, we present evidence suggesting that recombinant IBV with a mutant S2\u2032 site (furin-S2\u2032 site) leads to higher mortality. Infection with mutant IBV induces severe encephalitis and breaks the blood\u2013brain barrier. The results of a neutralization test and immunoprotection experiment show that an original serum and vaccine can still provide effective protection in vivo and in vitro. This is the first demonstration of IBV-induced neural symptoms in chickens with encephalitis and the furin-S2\u2032 site as a determinant of neurotropism.<\/jats:p>","DOI":"10.3390\/v11100972","type":"journal-article","created":{"date-parts":[[2019,10,23]],"date-time":"2019-10-23T11:46:59Z","timestamp":1571831219000},"page":"972","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":60,"title":["The S2 Subunit of QX-type Infectious Bronchitis Coronavirus Spike Protein Is an Essential Determinant of Neurotropism"],"prefix":"10.3390","volume":"11","author":[{"given":"Jinlong","family":"Cheng","sequence":"first","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ye","family":"Zhao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gang","family":"Xu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keran","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenfeng","family":"Jia","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yali","family":"Sun","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jing","family":"Zhao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jia","family":"Xue","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanxin","family":"Hu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8200-312X","authenticated-orcid":false,"given":"Guozhong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,10,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1117","DOI":"10.3181\/0903-MR-94","article-title":"Coronavirus diversity, phylogeny and interspecies jumping","volume":"234","author":"Woo","year":"2009","journal-title":"Exp. Biol. Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"634","DOI":"10.1637\/10227-043012-Review.1","article-title":"Review of infectious bronchitis virus around the world","volume":"56","author":"Jackwood","year":"2012","journal-title":"Avian Dis."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"6150","DOI":"10.1128\/JVI.03372-12","article-title":"TMPRSS2 activates the human coronavirus 229E for cathepsin-independent host cell entry and is expressed in viral target cells in the respiratory epithelium","volume":"87","author":"Bertram","year":"2013","journal-title":"J. Virol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1319","DOI":"10.1016\/S0140-6736(03)13077-2","article-title":"Coronavirus as a possible cause of severe acute respiratory syndrome","volume":"361","author":"Peiris","year":"2003","journal-title":"Lancet"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1814","DOI":"10.1056\/NEJMoa1211721","article-title":"Isolation of a Novel Coronavirus from a Man with Pneumonia in Saudi Arabia","volume":"367","author":"Zaki","year":"2012","journal-title":"N. Engl. J. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"482","DOI":"10.1006\/viro.1995.0021","article-title":"Activation of Astrocytes in the Spinal Cord of Mice Chronically Infected with a Neurotropic Coronavirus","volume":"213","author":"Sun","year":"1995","journal-title":"Virology"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1038\/nrmicro1343","article-title":"Coronavirus infection of the central nervous system: Host-virus stand-off","volume":"4","author":"Bergmann","year":"2006","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3338","DOI":"10.1128\/JVI.73.4.3338-3350.1999","article-title":"Acute and persistent infection of human neural cell lines by human coronavirus OC43","volume":"73","author":"Arbour","year":"1999","journal-title":"J. Virol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"8824","DOI":"10.1128\/JVI.78.16.8824-8834.2004","article-title":"Human respiratory coronavirus OC43: Genetic stability and neuroinvasion","volume":"78","author":"Jacomy","year":"2004","journal-title":"J. Virol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/j.virol.2006.01.049","article-title":"Human coronavirus OC43 infection induces chronic encephalitis leading to disabilities in BALB\/C mice","volume":"349","author":"Jacomy","year":"2006","journal-title":"Virology"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"8913","DOI":"10.1128\/JVI.74.19.8913-8921.2000","article-title":"Neuroinvasion by human respiratory coronaviruses","volume":"74","author":"Arbour","year":"2002","journal-title":"J. Virol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"508","DOI":"10.3389\/fimmu.2014.00508","article-title":"Neutrophil-derived cytokines: Facts beyond expression","volume":"5","author":"Tecchio","year":"2014","journal-title":"Front. Immunol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/j.vetmic.2017.11.027","article-title":"Pathogenicity differences between QX-like and Mass-type infectious bronchitis viruses","volume":"213","author":"Cheng","year":"2018","journal-title":"Vet. Microbiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/j.vetmic.2017.03.010","article-title":"Analysis of antigenicity and pathogenicity reveals major differences among QX-like infectious bronchitis viruses and other serotypes","volume":"203","author":"Yan","year":"2017","journal-title":"Vet. Microbiol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1016\/j.vetmic.2018.10.019","article-title":"Pathogenicity differences between a newly emerged TW-like strain and a prevalent QX-like strain of infectious bronchitis virus","volume":"227","author":"Xu","year":"2016","journal-title":"Vet. Microbiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.vetmic.2016.08.017","article-title":"Pathogenicity of virulent infectious bronchitis virus isolate YN on hen ovary and oviduct","volume":"193","author":"Zhong","year":"2016","journal-title":"Vet. Microbiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/S0065-3527(06)66005-3","article-title":"The molecular biology of coronaviruses","volume":"65","author":"Masters","year":"2006","journal-title":"Adv. Virus Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/S0065-3527(05)64006-7","article-title":"Molecular interactions in the assembly of coronaviruses","volume":"64","author":"Rottier","year":"2005","journal-title":"Adv. Virus Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"8801","DOI":"10.1128\/JVI.77.16.8801-8811.2003","article-title":"The coronavirus spike protein is a class I virus fusion protein: Structural and functional characterization of the fusion core complex","volume":"77","author":"Bosch","year":"2003","journal-title":"J. Virol."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Maier, H.J., Bickerton, E., and Britton, P. (2015). Coronaviruses: Methods and Protocols, Humana Press.","DOI":"10.1007\/978-1-4939-2438-7"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"8887","DOI":"10.1128\/JVI.00415-08","article-title":"Cathepsin L functionally cleaves the severe acute respiratory syndrome coronavirus class I fusion protein upstream of rather than adjacent to the fusion peptide","volume":"82","author":"Bosch","year":"2008","journal-title":"J. Virol."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Burkard, C., Verheije, M.H., Wicht, O., van Kasteren, S.I., van Kuppeveld, F.J., Haagmans, B.L., Pelkmans, L., Rottier, P.J., Bosch, B.J., and de Haan, C.A. (2014). Coronavirus cell entry occurs through the endo-\/lysosomal pathway in a proteolysis-dependent manner. PLoS Pathog., 10.","DOI":"10.1371\/journal.ppat.1004502"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/0168-1702(84)90070-4","article-title":"Replication and morphogenesis of avian coronavirus in Vero cells and their inhibition by monensin","volume":"1","author":"Matsuoka","year":"1984","journal-title":"Virus Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e01044","DOI":"10.1128\/JVI.01044-18","article-title":"The S2 subunit of infectious bronchitis virus beaudette is a determinant of cellular tropism","volume":"92","author":"Bickerton","year":"2018","journal-title":"J. Virol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1681","DOI":"10.1099\/jgv.0.001167","article-title":"Recombinant infectious bronchitis viruses expressing heterologous S1 subunits: Potential for a new generation of vaccines that replicate in Vero cells","volume":"99","author":"Bickerton","year":"2018","journal-title":"J. Gen. Virol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1994","DOI":"10.3201\/eid1812.120552","article-title":"Virulent avian infectious bronchitis virus, People\u2019s Republic of China","volume":"18","author":"Feng","year":"2012","journal-title":"Emerg. Infect. Dis."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1880","DOI":"10.1016\/j.vaccine.2018.02.053","article-title":"Attenuation, safety, and efficacy of a QX-like infectious bronchitis virus serotype vaccine","volume":"36","author":"Yan","year":"2018","journal-title":"Vaccine"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"12359","DOI":"10.1128\/JVI.75.24.12359-12369.2001","article-title":"Reverse genetics system for the avian coronavirus infectious bronchitis virus reverse genetics system for the avian coronavirus infectious bronchitis virus","volume":"75","author":"Casais","year":"2001","journal-title":"J. Virol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"493","DOI":"10.1093\/oxfordjournals.aje.a118408","article-title":"A simple method of estimating fifty per cent endpoints","volume":"27","author":"Reed","year":"1938","journal-title":"Am. J. Epidemiol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1016\/j.vetmic.2015.07.036","article-title":"Safety and efficacy of an attenuated Chinese QX-like infectious bronchitis virus strain as a candidate vaccine","volume":"180","author":"Zhao","year":"2015","journal-title":"Vet. Microbiol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"712","DOI":"10.1128\/JVI.01933-08","article-title":"Protease-mediated entry via the endosome of human coronavirus 229E","volume":"83","author":"Kawase","year":"2008","journal-title":"J. Virol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"970","DOI":"10.4049\/jimmunol.160.2.970","article-title":"Dynamic regulation of alpha- and beta-chemokine ex-pression in the central nervous system during mouse hepatitis virus-induced demyelinating disease","volume":"160","author":"Lane","year":"1998","journal-title":"J. Immunol."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Hosking, M.P., Liu, L., Ransohoff, R.M., and Lane, T.E. (2009). A protective role for ELR+ chemokines during acute viral encephalomyelitis. PLoS Pathog., 5.","DOI":"10.1371\/journal.ppat.1000648"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Le Coupanec, A., Desforges, M., Meessen-Pinard, M., Dub\u00e9, M., Day, R., Seidah, N.G., and Talbot, P.J. (2015). Cleavage of a neuroinvasive human respiratory virus spike glycoprotein by proprotein convertases modulates neurovirulence and virus spread within the central nervous system. PLoS Pathog., 11.","DOI":"10.1371\/journal.ppat.1005261"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"279","DOI":"10.3109\/13550284.2010.497806","article-title":"Mutations in the spike glycoprotein of human coronavirus OC43 modulate disease in BALB\/c mice from encephalitis to flaccid paralysis and demyelination","volume":"16","author":"Jacomy","year":"2010","journal-title":"J. Neurovirol."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Shang, J., Zheng, Y., Yang, Y., Liu, C., Geng, Q., Luo, C., Zhang, W., and Li, F. (2018). Cryo-EM structure of infectious bronchitis coronavirus spike protein reveals structural and functional evolution of coronavirus spike proteins. PLoS Pathog., 14.","DOI":"10.2210\/pdb6cv0\/pdb"}],"container-title":["Viruses"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1999-4915\/11\/10\/972\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:28:24Z","timestamp":1760189304000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1999-4915\/11\/10\/972"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,10,22]]},"references-count":36,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2019,10]]}},"alternative-id":["v11100972"],"URL":"https:\/\/doi.org\/10.3390\/v11100972","relation":{},"ISSN":["1999-4915"],"issn-type":[{"value":"1999-4915","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,10,22]]}}}