Cellular immunogenicity of novel gene immunogens in mice monitored by in vivo imaging

Mol Imaging. 2012 Nov-Dec;11(6):471-86.

Abstract

The efficient cell-mediated immune response clears cells expressing deoxyribonucleic acid (DNA) immunogens, but there are no methods to monitor this in vivo. We hypothesized that immune-mediated clearance can be monitored in vivo if DNA immunogens are coexpressed with reporter(s). To test this, we designed genes encoding human immunodeficiency virus 1 (HIV-1) reverse transcriptase (RT) fused via its N- or C-terminus to 30-amino acid-long Gly-Ala-repeat of Epstein-Barr virus nuclear antigen 1 or via the N-terminus to the transport signal of invariant chain/Ii or inserted between the cytoplasmic and luminal domains of lysosome-associated membrane protein I (LAMP). DNA immunogens mixed with luciferase gene were injected into BALB/c mice with subsequent electroporation. Reporter expression seen as luminescence was monitored by in vivo imaging. When luminescence faded, mice were sacrificed, and their splenocytes were stimulated with RT-derived antigens. Fading of luminescence correlated with the RT-specific secretion of interferon-γ and interleukin-2. Both immune and in vivo imaging techniques concordantly demonstrated an enhanced immunogenicity of RT-LAMP and of the N-terminal Gly-Ala-RT fusion genes. In vivo imaging performed as an animal-sparing method to estimate the overall performance of DNA immunogens, predicting it early in the experiment. So far, in vivo imaging cannot be a substitute for conventional immune assays, but it is supplementary to them. Further experiments are needed to identify which arms of cellular immune response in vivo imaging monitors best.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • CD4-Positive T-Lymphocytes / immunology
  • Epitopes / immunology
  • Female
  • HEK293 Cells
  • HIV Reverse Transcriptase / immunology
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Optical Imaging*
  • T-Lymphocytes / immunology
  • Vaccines, DNA / immunology
  • Vaccines, Synthetic / genetics
  • Vaccines, Synthetic / immunology*

Substances

  • Epitopes
  • Vaccines, DNA
  • Vaccines, Synthetic
  • reverse transcriptase, Human immunodeficiency virus 1
  • HIV Reverse Transcriptase