title: Antigenicity analysis of different regions of the severe acute respiratory syndrome coronavirus nucleocapsid protein.
abstract: BACKGROUND
  The widespread threat of severe acute respiratory syndrome (SARS) to human health has made urgent the development of fast and accurate analytical methods for its early diagnosis and a safe and efficient antiviral vaccine for preventive use. For this purpose, we investigated the antigenicity of different regions of the SARS coronavirus (SARS-CoV) nucleocapsid (N) protein.
  
  
  METHODS
  The cDNA for full-length N protein and its various regions from the SARS-CoV was cloned and expressed in Escherichia coli. After purification, all of the protein fragments were printed on glass slides to fabricate a protein microarray and then probed with the sera from SARS patients to determine the reactivity of these protein fragments.
  
  
  RESULTS
  The full-length protein and two other fragments reacted with all 52 sera tested. Four important regions with possible epitopes were identified and named as EP1 (amino acids 51-71), EP2 (134-208), EP3 (249-273), and EP4 (349-422), respectively. EP2 and EP4 possessed linear epitopes, whereas EP1 and EP2 were able to form conformational epitopes that could react with most (>80%) of the tested sera. EP3 and EP4 also formed conformational epitopes, and antibodies against these epitopes existed in all 52 of the sera tested.
  
  
  CONCLUSIONS
  The N protein is a highly immunogenic protein of the SARS-CoV. Conformational epitopes are important for this protein, and antigenicity of the COOH terminus is higher than that of the NH(2) terminus. The N protein is a potential diagnostic antigen and vaccine candidate for SARS-CoV.
authors.affiliation: Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, China.
authors.forename: Zeliang
authors.initials: Z
authors.lastname: Chen
authors.forename: Decui
authors.initials: D
authors.lastname: Pei
authors.forename: Lingxiao
authors.initials: L
authors.lastname: Jiang
authors.forename: Yajun
authors.initials: Y
authors.lastname: Song
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Hongxia
authors.initials: H
authors.lastname: Wang
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Zhou
authors.forename: Junhui
authors.initials: J
authors.lastname: Zhai
authors.forename: Zongmin
authors.initials: Z
authors.lastname: Du
authors.forename: Bei
authors.initials: B
authors.lastname: Li
authors.forename: Maofeng
authors.initials: M
authors.lastname: Qiu
authors.forename: Yanping
authors.initials: Y
authors.lastname: Han
authors.forename: Zhaobiao
authors.initials: Z
authors.lastname: Guo
authors.forename: Ruifu
authors.initials: R
authors.lastname: Yang
mesh_terms: D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D000086462:Coronavirus Nucleocapsid Proteins; D018076:DNA, Complementary / Q000235:genetics; D000939:Epitopes; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D019590:Nucleocapsid Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D040081:Protein Array Analysis; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology* / Q000302:isolation & purification; D045169:Severe Acute Respiratory Syndrome / Q000175:diagnosis
chemical_list: D000956:Antigens, Viral; D000086462:Coronavirus Nucleocapsid Proteins; D018076:DNA, Complementary; D000939:Epitopes; D019590:Nucleocapsid Proteins