Immunogenicity and protective efficacy of mycobacterial DNA vaccines incorporating plasmid‐encoded cytokines against Mycobacterium bovis

Abstract

DNA-based vaccines, alone or in combination with other sub-unit vaccination regimes, represent an alternative to live mycobacterial vaccines for protective immunization against tuberculosis. Here, we have used a murine immunization or Mycobacteriam bovis aerosol challenge model to assess the immunogenicity and protective efficacy of mycobacterial DNA vaccines. Mice that received immunization with DNA constructs encoding M. bovis antigen 85A (Ag85-A) and arget(ESAT-6) produced measurable interferon-gamma (IFN-c) responses to CD4 + T-cell epitope-peptide recall antigens in vitro. The magnitude of these responses was enhanced by co-delivery of a construct encoding murine cytokines (macrophage inhibitory protein (MIP)-1a or interleukin(IL)-7), although they did not the match responses observed in mice that received Bacille CalmetteÀGuerin(BCG) immunisation. In contrast, DNA priming followed by boosting with modified vaccinia Ankara (MVA) vaccine (expressing M. tuberculosis Ag85-A) invoked higher IFN-c levels, with the most immunogenic regime of Ag85 or ESAT or IL-7 prime followed by MVA boost being of commensurate immunogenicity to BCG. Despite this, neither DNA alone nor DNA-prime or MVA boost regimes conferred measurable protection against aerosol challenge with virulent M. bovis. These data highlight both the promise and the shortcomings of new generation subunit tuberculosis vaccines, with particular emphasis on their potential as vaccines against M. bovis.

Prokaryotic Expression and Identification on the ag85a and mpb70 Fusion Gene of <i>Mycobacterium bovis</i>

“…To increase the immunoreaction of single gene and antigen, many scholars have evolved immunity investigation on fusion genes and proteins. Ag85A/ESAT6 DNA vaccines-MVA enhanced the resistance anti-M. bovis aerosol [10]. Mouse vaccinated with Ag85A-ESAT-6 polyester beads packaged by E. coli and Lactococcus lactis produced high-level IgG, INF-γ, IL-2, IL-6,TNF-α and IL-17a in vivo.…”

Fusion and Prokaryotic Expression on the mpb83 and mpb63 Genes of Mycobacterium Bovis

“…M.bovis fusion vaccines of mpb64,ag85b and esat-6 can stimulate mouse produce high level antibody, lymphocyte, INF-γ and IL-2, and the protective result reached the immunoprotection level of BCG [14]. C57BL/6 mice was vaccinated with recombinant BCG(constructed with Ag85B-Rv3425 and Ag85B-MPT64-Mbt8.4 respectively), the results indicated that the level of antigen-stimulated T cells expressing IFN-γ and antibody titer were significantly higher than that of BCG [15,16], the level of IFN-γ demonstrated notable difference, rBCG has preferably immunoprotection [16].Ag85A/ESAT6 DNA vaccines -MVA enhanced the resistance anti-M. bovis aerosol [17]. Recombinant fusion protein…”

Construction of Eukaryotic Expression Vector and Transient Expression on <i>Mycobacterium bovis mpb83</i>,<i>mpb70</i> and Cattle<i> il-15</i> Gene

“…But significant differences in spleen bacterial counts were observed between those receiving PHB beads and BCG and PBS. Young, et al [26] used murine immunization and M. bovis aerosol challenge model to assess the immunogenicity and protective efficacy of mycobacterial DNA vaccines Ag85A/ESAT6.The results demonstrated that Ag85A/ESAT6 DNA vaccines-MVA enhanced the resistance anti-M. bovis aerosol. Abel, et al [27] and Hoft, et al [28] investigated the safety and immunogenicity in healthy M. tuberculosis-uninfected BCG-vaccinated adults from a tuberculosis-endemic region of South Africa and USA, the results confirmed that recombinant fusion protein Ag85A-Ag85B-TB10.4 can stimulate strongly CD 4 + T cells reaction and persistant CD 8 + T cells reaction, and is a promising vaccine.…”