Immune responses to T-cell epitopes of SARS CoV-N protein are enhanced by N immunization with a chimera of lysosome-associated membrane protein

Gene Ther. 2009 Nov;16(11):1353-62. doi: 10.1038/gt.2009.92. Epub 2009 Sep 3.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Viral / biosynthesis
  • Coronavirus Nucleocapsid Proteins
  • Epitopes, T-Lymphocyte / immunology*
  • Female
  • Immunity, Cellular
  • Immunization / methods
  • Immunization Schedule
  • Immunologic Memory
  • Interferon-gamma / biosynthesis
  • Interleukins / biosynthesis
  • Lysosome-Associated Membrane Glycoproteins / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Nucleocapsid Proteins / immunology*
  • Spleen / immunology
  • Transfection
  • Vaccines, DNA / immunology
  • Viral Vaccines / immunology*

Substances

  • Antibodies, Viral
  • Coronavirus Nucleocapsid Proteins
  • Epitopes, T-Lymphocyte
  • Interleukins
  • Lysosome-Associated Membrane Glycoproteins
  • Nucleocapsid Proteins
  • Vaccines, DNA
  • Viral Vaccines
  • Interferon-gamma