Enhanced immune response and protection efficacy of a DNA vaccine constructed by linkage of the Mycobacterium tuberculosis Ag85B-encoding gene with the BVP22-encoding gene

J Med Microbiol. 2009 Apr;58(Pt 4):462-468. doi: 10.1099/jmm.0.004267-0.

Abstract

Plasmid DNA vaccines have been widely explored for use in tuberculosis immunization but their immunogenicity needs improvement. In the present study, we incorporated the bovine herpesvirus 1 VP22 (BVP22)-encoding gene, which encodes a protein that demonstrates a capability for disseminating the expressed antigen to neighbouring cells, into a DNA vector in which it was fused to the Ag85B-encoding gene of Mycobacterium tuberculosis (Mtb), and investigated whether this linkage could enhance immune response and protective efficacy in C57BL/6 mice compared to plasmid DNA encoding Ag85B alone. After immunization in mice, Ag85B-specific ELISA antibodies and spleen lymphocyte proliferative responses induced by DNA co-expressing BVP22 and Ag85B were significantly higher than those obtained in mice immunized with Ag85B-encoding DNA alone, except for the number of gamma interferon secreting cells. In addition, based on histopathological examination and bacterial-load determination in lung and spleen, protection against intravenous Mtb H37Rv challenge evoked by the BVP22-Ag85B DNA immunization exceeded the response elicited by Ag85B DNA alone, which was not significantly different from that provided by Bacillus Calmette-Guérin (BCG). These results suggested that DNA vaccine consisting of BVP22 and Ag85B-encoding DNA enhanced immune response and protection against intravenous Mtb H37Rv challenge in mice, indicating that BVP22-encoding DNA might be a promising tool to enhance TB DNA vaccine efficacy.

MeSH terms

  • Animals
  • Antibodies, Bacterial / biosynthesis
  • Antigens, Bacterial / genetics*
  • Antigens, Bacterial / immunology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology
  • Cell Proliferation
  • Female
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial / genetics*
  • Genes, Bacterial / immunology
  • HeLa Cells
  • Humans
  • Immunoglobulin G / blood
  • Interferon-gamma / metabolism
  • Lung / pathology
  • Lymphocytes / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mycobacterium tuberculosis / genetics*
  • Mycobacterium tuberculosis / immunology*
  • Random Allocation
  • Spleen / cytology
  • Tuberculosis / immunology
  • Tuberculosis / prevention & control
  • Tuberculosis Vaccines / immunology*
  • Tuberculosis Vaccines / standards
  • Vaccines, DNA / immunology*
  • Vaccines, DNA / standards

Substances

  • Antibodies, Bacterial
  • Antigens, Bacterial
  • Bacterial Proteins
  • Immunoglobulin G
  • Tuberculosis Vaccines
  • Vaccines, DNA
  • Interferon-gamma