title: SARS coronavirus nucleocapsid immunodominant T-cell epitope cluster is common to both exogenous recombinant and endogenous DNA-encoded immunogens.
abstract: Correspondence between the T-cell epitope responses of vaccine immunogens and those of pathogen antigens is critical to vaccine efficacy. In the present study, we analyzed the spectrum of immune responses of mice to three different forms of the SARS coronavirus nucleocapsid (N): (1) exogenous recombinant protein (N-GST) with Freund's adjuvant; (2) DNA encoding unmodified N as an endogenous cytoplasmic protein (pN); and (3) DNA encoding N as a LAMP-1 chimera targeted to the lysosomal MHC II compartment (p-LAMP-N). Lysosomal trafficking of the LAMP/N chimera in transfected cells was documented by both confocal and immunoelectron microscopy. The responses of the immunized mice differed markedly. The strongest T-cell IFN-gamma and CTL responses were to the LAMP-N chimera followed by the pN immunogen. In contrast, N-GST elicited strong T cell IL-4 but minimal IFN-gamma responses and a much greater antibody response. Despite these differences, however, the immunodominant T-cell ELISpot responses to each of the three immunogens were elicited by the same N peptides, with the greatest responses being generated by a cluster of five overlapping peptides, N76-114, each of which contained nonameric H2d binding domains with high binding scores for both class I and, except for N76-93, class II alleles. These results demonstrate that processing and presentation of N, whether exogenously or endogenously derived, resulted in common immunodominant epitopes, supporting the usefulness of modified antigen delivery and trafficking forms and, in particular, LAMP chimeras as vaccine candidates. Nevertheless, the profiles of T-cell responses were distinctly different. The pronounced Th-2 and humoral response to N protein plus adjuvant are in contrast to the balanced IFN-gamma and IL-4 responses and strong memory CTL responses to the LAMP-N chimera.
authors.affiliation: Division of Biomedical Sciences, Johns Hopkins in Singapore, 31 Biopolis Way, #02-01 The Nanos, Singapore 138669, Singapore.
authors.forename: Vandana
authors.initials: V
authors.lastname: Gupta
authors.forename: Tani M
authors.initials: TM
authors.lastname: Tabiin
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: Ananth
authors.initials: A
authors.lastname: Chandrasekaran
authors.forename: Azlinda
authors.initials: A
authors.lastname: Anwar
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.forename: Priya
authors.initials: P
authors.lastname: Chikhlikar
authors.forename: Jerome
authors.initials: J
authors.lastname: Salmon
authors.forename: Vladimir
authors.initials: V
authors.lastname: Brusic
authors.forename: Ernesto T A
authors.initials: ET
authors.lastname: Marques
authors.forename: Srinivasan N
authors.initials: SN
authors.lastname: Kellathur
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: August
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D000956:Antigens, Viral / Q000235:genetics; D001483:Base Sequence; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D000086462:Coronavirus Nucleocapsid Proteins; D004279:DNA, Viral / Q000235:genetics; D016056:Immunodominant Epitopes / Q000235:genetics; D051379:Mice; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D019590:Nucleocapsid Proteins / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D045473:Severe acute respiratory syndrome-related coronavirus / Q000235:genetics / Q000276:immunology*; D018411:Spodoptera; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D000086462:Coronavirus Nucleocapsid Proteins; D004279:DNA, Viral; D016056:Immunodominant Epitopes; D019590:Nucleocapsid Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014765:Viral Vaccines