title: Enhanced murine antigen-specific gamma interferon and immunoglobulin G2a responses by using mycobacterial ESAT-6 sequences in DNA vaccines.
abstract: The Mycobacterium tuberculosis protein ESAT-6 has unusual immune stimulating activities, has been implicated in the recall of long-lived immunity, and induces protection against tuberculosis in mice. For many diseases caused by bacterial or viral pathogens, a strong cell-mediated immune (i.e., type 1) response is often required for recovery or protection. Therefore, it is important to design immunization regimens that induce agent-specific type 1 immunity. We have shown in previous studies that ESAT-6 could enhance antigen-specific type 1 immune responses in BALB/c mice against a second antigen when presented as a purified fusion protein. It was also of interest to determine if ESAT-6 could enhance the type 1 response against a second antigen beyond that afforded by DNA vaccination through CpG motifs. This was tested by using gene fusions of ESAT-6 and the Mycoplasma hyopneumoniae surface antigen P71. Modified P71 gene sequences were cloned with or without ESAT-6 sequences into a DNA vaccine vector and were used to immunize mice. Splenic lymphocytes from vaccinated mice were tested for gamma interferon (IFN-gamma) and interleukin-10 (IL-10) secretion. Serum antibodies were examined for P71 antigen-specific isotype responses. When stimulated in vitro with purified P71 antigen, splenocytes from the ESAT-6:P71 vaccinates secreted higher levels of IFN-gamma and lower levels of IL-10 compared to those of vaccinates receiving the P71 construct alone. Furthermore, the immunoglobulin G2a serum antibody levels were significantly higher in the ESAT-6:P71 vaccinates compared to those of the vaccinates receiving P71 alone. In conclusion, ESAT-6 was shown to enhance antigen-specific type 1 immune responses in BALB/c mice when used in DNA vaccines.
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA 50011, USA. fcminion@iastate.edu
authors.forename: F Chris
authors.initials: FC
authors.lastname: Minion
authors.forename: Sreekumar A
authors.initials: SA
authors.lastname: Menon
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Mahairas
authors.forename: M J
authors.initials: MJ
authors.lastname: Wannemuehler
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D005260:Female; D007074:Immunoglobulin G / Q000096:biosynthesis*; D007371:Interferon-gamma / Q000096:biosynthesis*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000276:immunology; D009175:Mycoplasma Infections / Q000276:immunology / Q000517:prevention & control*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000276:immunology; D019444:Vaccines, DNA / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D007074:Immunoglobulin G; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; C470789:p71 membrane protein, Mycoplasma hyopneumoniae; D007371:Interferon-gamma