Immune responses to T-cell epitopes of SARS CoV-N protein are enhanced by N immunization with a chimera of lysosome-associated membrane protein.
In our previous study by Gupta et al, dominant T-cell epitopes of SARS CoV-N(N) protein were predicted by software. The spectrum of interferon (IFN)-gamma responses of Balb/c mice immunized against two different forms of SARS CoV-N plasmid was then analyzed. A cluster of dominant T-cell epitopes of SARS CoV-N protein was found in the N-terminus (amino acids 76-114). On the basis of this study, four different plasmids were constructed: (i) DNA encoding the unmodified N (p-N) or N(70-122) (p-N(70-122)) as an endogenous cytoplasmic protein or (ii) DNA encoding a lysosome-associated membrane protein (LAMP) chimera with N (p-LAMP/N) or N(70-122) (p-LAMP/N(70-122)). The immune responses of mice to these four constructs were evaluated. The results showed marked differences in the responses of the immunized mice. A single priming immunization with the p-LAMP/N construct was sufficient to elicit an antibody response. Enzyme-linked immunospot (ELISpot) assay indicated that p-LAMP/N(70-122) and p-LAMP/N plasmids both elicited a greater IFN-gamma response than p-N. p-N and p-N(70-122) constructs induced low or undetectable levels of cytokine secretion. We also found that the p-LAMP/N(70-122) construct promoted a long-lasting T-cell memory response without an additional boost 6 months after three immunizations. These findings show that DNA vaccines, even epitope-based DNA vaccines using LAMP as chimera, can elicit both humoral and cellular immune responses.
Yang
K
K
Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. yangkunkun@fmmu.edu.cn
Sun
K
K
Srinivasan
K N
KN
Salmon
J
J
Marques
E T
ET
Xu
J
J
August
J T
JT
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D000086462:Coronavirus Nucleocapsid Proteins; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D007111:Immunity, Cellular; D007114:Immunization / Q000379:methods; D007115:Immunization Schedule; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D007378:Interleukins / Q000096:biosynthesis; D051907:Lysosomal Membrane Proteins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D019590:Nucleocapsid Proteins / Q000276:immunology*; D013154:Spleen / Q000276:immunology; D014162:Transfection; D019444:Vaccines, DNA / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
D000914:Antibodies, Viral; D000086462:Coronavirus Nucleocapsid Proteins; D018984:Epitopes, T-Lymphocyte; D007378:Interleukins; D051907:Lysosomal Membrane Proteins; D019590:Nucleocapsid Proteins; D019444:Vaccines, DNA; D014765:Viral Vaccines; D007371:Interferon-gamma