Improved Protective Efficacy of a Species-Specific DNA Vaccine Encoding Mycolyl-Transferase Ag85A from Mycobacterium ulcerans by Homologous Protein Boosting

Vaccination with plasmid DNA encoding Ag85A from M. bovis BCG can partially protect C57BL/6 mice against a subsequent footpad challenge with M. ulcerans. Unfortunately, this cross-reactive protection is insufficient to completely control the infection. Although genes encoding Ag85A from M. bovis BCG (identical to genes from M. tuberculosis) and from M. ulcerans are highly conserved, minor sequence differences exist, and use of the specific gene of M. ulcerans could possibly result in a more potent vaccine. Here we report on a comparison of immunogenicity and protective efficacy in C57BL/6 mice of Ag85A from M. tuberculosis and M. ulcerans, administered as a plasmid DNA vaccine, as a recombinant protein vaccine in adjuvant or as a combined DNA prime-protein boost vaccine. All three vaccination formulations induced cross-reactive humoral and cell-mediated immune responses, although species-specific Th1 type T cell epitopes could be identified in both the NH2-terminal region and the COOH-terminal region of the antigens. This partial species-specificity was reflected in a higher—albeit not sustained—protective efficacy of the M. ulcerans than of the M. tuberculosis vaccine, particularly when administered using the DNA prime-protein boost protocol

Improved Protective Efficacy of a Species-Specific DNA Vaccine Encoding Mycolyl-Transferase Ag85A from Mycobacterium ulcerans by Homologous Protein Boosting

Vaccination with plasmid DNA encoding Ag85A from M. bovis BCG can partially protect C57BL/6 mice against a subsequent footpad challenge with M. ulcerans. Unfortunately, this cross-reactive protection is insufficient to completely control the infection. Although genes encoding Ag85A from M. bovis BCG (identical to genes from M. tuberculosis) and from M. ulcerans are highly conserved, minor sequence differences exist, and use of the specific gene of M. ulcerans could possibly result in a more potent vaccine. Here we report on a comparison of immunogenicity and protective efficacy in C57BL/6 mice of Ag85A from M. tuberculosis and M. ulcerans, administered as a plasmid DNA vaccine, as a recombinant protein vaccine in adjuvant or as a combined DNA prime-protein boost vaccine. All three vaccination formulations induced cross-reactive humoral and cell-mediated immune responses, although species-specific Th1 type T cell epitopes could be identified in both the NH2-terminal region and the COOH-terminal region of the antigens. This partial species-specificity was reflected in a higher—albeit not sustained—protective efficacy of the M. ulcerans than of the M. tuberculosis vaccine, particularly when administered using the DNA prime-protein boost protocol

Incipient Balancing Selection through Adaptive Loss of Aquaporins in Natural Saccharomyces cerevisiae Populations

A major goal in evolutionary biology is to understand how adaptive evolution has influenced natural variation, but identifying loci subject to positive selection has been a challenge. Here we present the adaptive loss of a pair of paralogous genes in specific Saccharomyces cerevisiae subpopulations. We mapped natural variation in freeze-thaw tolerance to two water transporters, AQY1 and AQY2, previously implicated in freeze-thaw survival. However, whereas freeze-thaw–tolerant strains harbor functional aquaporin genes, the set of sensitive strains lost aquaporin function at least 6 independent times. Several genomic signatures at AQY1 and/or AQY2 reveal low variation surrounding these loci within strains of the same haplotype, but high variation between strain groups. This is consistent with recent adaptive loss of aquaporins in subgroups of strains, leading to incipient balancing selection. We show that, although aquaporins are critical for surviving freeze-thaw stress, loss of both genes provides a major fitness advantage on high-sugar substrates common to many strains' natural niche. Strikingly, strains with non-functional alleles have also lost the ancestral requirement for aquaporins during spore formation. Thus, the antagonistic effect of aquaporin function—providing an advantage in freeze-thaw tolerance but a fitness defect for growth in high-sugar environments—contributes to the maintenance of both functional and nonfunctional alleles in S. cerevisiae. This work also shows that gene loss through multiple missense and nonsense mutations, hallmarks of pseudogenization presumed to emerge after loss of constraint, can arise through positive selection

Evaluation de l'utilisation d'un vaccin unique contre la tuberculose et l'ulcère de Buruli basé sur des antigènes homologues immuno-dominants

Doctorat en sciences médicalesinfo:eu-repo/semantics/nonPublishe

Evaluation de l'utilisation d'un vaccin unique contre la tuberculose et l'ulcère de Buruli basé sur des antigènes homologues immuno-dominants

Doctorat en sciences médicalesinfo:eu-repo/semantics/nonPublishe

A Booster Vaccination with Mycobacterium bovis BCG Does Not Increase the Protective Effect of the Vaccine against Experimental Mycobacterium ulcerans Infection in Mice

Buruli ulcer, caused by Mycobacterium ulcerans, is a necrotizing skin disease emerging particularly in West Africa. M. bovis BCG vaccine offers only short-term protection against experimental footpad infection of C57BL/6 mice with M. ulcerans, and the duration of this protection cannot be prolonged by a booster vaccination

Immunodominant peptides of Ag 85 A from <i>M. ulcerans</i> and <i>M. tuberculosis</i>.

*<p>Bold Amino Acids are high conserved amino acid differences (determined according to the Needleman-Wunsh criterion) and Amino Acids underlined are the non-conserved aa difference in comparison to the Ag85A peptides of <i>M. tuberculosis</i>.</p

Spleen cell IL-2 (A) and IFN-γ (B) responses to whole Ag85A- <i>M. ulcerans</i> and its synthetic peptides, as tested on a pool of six B6 mice vaccinated 3 times at three weeks interval with Ag85A-DNA <i>M. ulcerans</i> (white bars) or Ag85A-DNA <i>M. tuberculosis</i> (black bars).

<p>Graph in insert represents the cytokine production in response to partial Ag85A <i>M. ulcerans</i> aa 17–150. Unstimulated cells (grey bars). Data of insert represent mean±SD values of 3 mice tested individually.</p

Spleen cell IL-2 (A) and IFN-γ (B) responses to RPMI medium (grey bars), recombinant Ag85A from <i>M. ulcerans</i> (white bars) and <i>M. tuberculosis</i> (black bars) in B6 mice vaccinated with Ag85A DNA, Ag85A protein or Ag85A DNA boosted with protein in Gerbu adjuvant, 3 months after the third immunization.

<p>Cytokines levels tested on 24 h (IL-2) and 72 h (IFN-γ) culture supernatant of 4 mice tested individually/group. Data presented as means±SDs intra-assay. Statistically significant results as compared to the DNA vaccinated <i>M. ulcerans</i> or <i>M. tuberculosis</i> groups are represented in the figure by *** (P<0.001), ** (P<0.01) and * (P<0.05). The first group of comparison take all of the vaccinated mice compared to the DNA vaccinated mice in response to recombinant Ag85A from <i>M. ulcerans</i>. The second group of comparison take all of the vaccinated mice compared to the DNA vaccinated mice in response to recombinant Ag85A from <i>M. tuberculosis.</i></p