The Electronic Influence of Abasic Sites in DNA

Abasic sites in DNA are prevalent as both naturally forming defects and as synthetic inclusions for biosensing applications. The electronic impact of these defects in DNA sensor and device configurations has yet to be clarified. Here we report the effect of an abasic site on the rate and yield of charge transport through temperature-controlled analysis of DNA duplex monolayers on multiplexed devices. Transport yield through the abasic site monolayer strongly increases with temperature, but the yield relative to an undamaged monolayer decreases with temperature. This is opposite to the increasing relative yield with temperature from a mismatched base pair, and these effects are accounted for by the unique structural impact of each defect. Notably, the effect of the abasic site is nearly doubled when heated from room temperature to 37 °C. The rate of transport is largely unaffected by the abasic site, showing Arrhenius-type behavior with an activation energy of ∼300 meV. Detailed abasic site investigation elucidates the electrical impact of these biologically spontaneous defects and aids development of biological sensors

Removal of asparaginyl endopeptidase inhibition by LsCPI increases its immunogenicity.

<p>Mice were immunised against LsCPI with plasmids encoding either the native protein (CPI) or a plasmid expressing its mutated form (CPIm), in combination with pIL4+pFlt3L+pMIP or alone. All mice other than naïve were challenged with live infective <i>L. sigmodontis</i> larvae. (A), LsCPI-specific IgG1 (b vs. [a, ab], <i>P</i> = 0.02, 0.3), and (B), total serum IgE concentrations (a, <i>P</i>≤0.001). ELISAs were performed with recombinant LsCPI. (C), Parasite survival 60d after infection. pEmpty, non-coding plasmid control; CPI, pcDNA 3.1 plasmid with an insert encoding LsCPI; CPIm, mutated form of LsCPI; adj = pIL4+pFlt3L+pMIP. Points represent individual mice at D60 p.i. (N = 5 mice per group).</p

Long-term impact of vaccination on microfilarial load in the absence of ivermectin treatment.

<p>The green <b>(A)</b>, blue <b>(B)</b> and red <b>(C)</b> lines correspond to, respectively, a pre-control endemicity of 40%, 60%, and 80% microfilarial prevalence. The solid lines indicate the pre-control contribution of each group to the overall microfilarial load, which is the product of multiplying the microfilarial age- and sex specific profiles (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003938#pntd.0003938.g003" target="_blank">Fig 3B</a>) times the proportion of hosts in each demographic stratum, i.e. the proportion of hosts in each age and sex group (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003938#pntd.0003938.g002" target="_blank">Fig 2</a>). The sum total of the age- and sex-specific contributions yields the overall mean microfilarial load. The dotted lines correspond to the values after 15 years of vaccination. The shaded area illustrates the reduction in microfilarial load in those aged less than 20 years. Modelling assumptions are as follows: a vaccination programme targeting initially 1–5 year olds with continuous vaccination of one year olds after the first year of the programme; an initial prophylactic efficacy against the development of incoming worms of 50%; an initial therapeutic efficacy against skin microfilarial load of 90%; a mean duration of protective and therapeutic effects of 20 years (rate of decay = 0.05 per year) and an 80% coverage of vaccination.</p

Enhancing type 2 immunity against LsCPI by targeting DCs.

<p>Mice were immunised with plasmids containing the CPI, decCPI, CPIm or decCPIm construct. (A), LsCPI-specific IgG1 concentrations (b vs. a, <i>P</i>≤3×10⁻⁵), (B), total IgE serum concentrations (a, <i>P</i>≤0.05), and (C–D) adult parasite survival and microfilariae peripheral blood densities. All groups except naïve received pIL4+pFlt3L+pMIP. isoOVA, control plasmid expressing OVA fused to an isotype control for sc-Fv-DEC205; CPI, pcDNA 3.1 plasmid with an insert encoding LsCPI; CPIm, mutated form of LsCPI. Points represent individual mice at D60 p.i. (N = 5 mice per group).</p

Protective immunity is mediated by IgG1 and pleural leukocyte recruitment.

<p>A principal component analysis was performed on 31 immunological measures from the mice in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001968#pntd-0001968-g006" target="_blank">Figure 6C–D</a> (see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001968#pntd.0001968.s004" target="_blank">Table S1</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001968#pntd.0001968.s003" target="_blank">Figure S3</a> for PC selection) to identify immune responses associated with the killing of adult worms. The second component was most strongly associated with parasite-specific IgG1 and pleural leukocyte recruitment, and was the only component negatively correlated with parasite survival (r = −0.72, <i>P</i><0.0001). pEmpty, non-coding plasmid control; decALTm, plasmid encoding the anti-DEC205 scFv-ALTm construct, decCPIm, plasmid encoding the anti-DEC205 scFv-CPIm construct, pIL4 pMIP and pFlt3L, plasmids expressing mouse IL-4, MIP-1α and Flt3L respectively. Points represent individual mice at D60 p.i. (N = 5 mice per group).</p

Long-term impact of vaccination on onchocerciasis annual transmission potential and microfilarial load in the absence of ivermectin treatment under different assumptions of initial vaccine efficacy.

<p><b>A:</b> Model assumes an initial vaccine efficacy against the development of incoming worms of 50% and against skin microfilarial load of 90%. <b>B:</b> Model assumes a higher initial vaccine efficacy against the development of incoming worms of 70% and against skin microfilarial load of 95%. Results assume mean duration of prophylactic and therapeutic effects of 20 years (rate of decay = 0.05 per year) and an 80% coverage of vaccination. Annual transmission potential (ATP): the average number of L3 larvae potentially received per person per year.</p><p>Long-term impact of vaccination on onchocerciasis annual transmission potential and microfilarial load in the absence of ivermectin treatment under different assumptions of initial vaccine efficacy.</p

Dual modified antigens in combination with cytokine-expressing plasmids generate protective immunity.

<p>Mice were immunised with decALTm, decCPIm, or both in addition to the adjuvant combinations pIL4+pFlt3L+pMIP, pIL4 alone or pFlt3L+pMIP. (A–B), Comparison of dual unmodified antigens and dual modified antigen formulations. (C–D), comparison of single modified vs. dual modified vaccine protective capacity. (E–F), comparison of Th2- and antigen presenting cell-promoting plasmids. (A, C, E), Proportion of adult parasites present in the pleural cavity of mice after 60 days of infection relative to infection dose (A: a, <i>P</i><4×10⁻¹³; C: c vs. [b, ab, a], <i>P</i> = 0.002, 4×10⁻⁵, 3×10⁻⁷). (B, D, F), number of microfilariae present in 30 µl of peripheral blood circulation (B: c vs. [b, a], <i>P</i> = 0.004, 8×10⁻¹⁴; F: b vs. a, <i>P</i>_d<0.04). pEmpty, non-coding plasmid control; decALTm, plasmid encoding the anti-DEC205 scFv-ALTm construct, decCPIm, plasmid encoding the anti-DEC205 scFv-CPIm construct, pIL4 pMIP and pFlt3L, plasmids expressing mouse IL-4, MIP-1α and Flt3L respectively. Points represent individual mice at D60 p.i. (A–D, N = 4–5 mice per group; E–F N = 9–10 mice per group).</p

Dendritic-cell targeted ALTm enhances humoral and cellular responses against LsALT.

<p>The sequence encoding ALTm was fused to the sequence for a single-chain antibody targeting DEC205 (decALTm) or to a control antibody sequence which was derived from an antibody of the same isotype that does not bind to DCs). All vaccinated mice were also injected with pIL-4, pMIP and pFlt3L. All groups except naïve mice were challenged with live infective <i>L. sigmodontis</i> larvae. The data shown are representative of results obtained at D10 and at D60 p.i. (A) Serum LsALT-specific IgG1 levels were significantly increased in the ALTm and decALTm groups relative to the control plasmids (b vs. [a, ab], <i>P</i>≤0.05, 0.8). (B) LsALT-specific IgG2a concentrations in serum were highly variable. ELISAs were performed with the wild-type recombinant LsALT. (C) Targeting ALTm to dendritic cells did not increase total total serum IgE or (D), eosinophil recruitment to the site of infection but IgE was significantly higher than in naïve controls (C, <i>P</i> = 0.02). Cytokines and cell enumerations were performed on pleural lavage fluid. (E), Parasite survival represented as the proportion of worms found in the pleural cavity of infected mice relative to the infective dose (except naive mice). pEmpty, non-coding plasmid control; ALTm, plasmid encoding the acidic domain-deleted sequence of LsALT; isoALTm, plasmid encoding a non-specific scFv control-ALTm construct; decALTm, plasmid encoding the anti-DEC205 scFv-ALTm construct. Points represent individual mice (N = 5 mice per group).</p

EPIONCHO’s underlying age- and sex-specific exposure and baseline microfilarial load profiles.

<p><b>(A)</b> The age- and sex-specific exposure profiles to blackfly bites calibrated to reproduce the observed pre-control age-dependent microfilarial loads. <b>(B)</b> The age- and sex-specific microfilarial loads in African savannah settings of northern Cameroon [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003938#pntd.0003938.ref032" target="_blank">32</a>]. Note that the fitting was performed using the individual data, not the binned data shown in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003938#pntd.0003938.g002" target="_blank">Fig 2B</a>. Note also that the legend on panel <b>(B)</b> applies to both panels <b>(A)</b> and <b>(B)</b>.</p

Coinjection of plasmids encoding IL-4 and MIP-1α+FLT3L marginally improves immunisation with LsALT-expressing plasmids.

<p>Mice were immunised with DNA plasmids expressing parasite LsALT (ALT) and murine IL-4 (pIL4) or MIP-1α (pMIP) and Flt3L (pFlt3L). Empty expression plasmid (pEmpty) was injected as a control for DNA-induced inflammation to equalise DNA quantities between groups. All groups were subsequently challenged with live infective <i>L. sigmodontis</i> larvae subcutaneously and infection was allowed to progress for 10 days. (A–B), LsALT-specific IgG1 and IgG2a, respectively and (C), concentrations of total IgE in the serum were increased by the coadministration of pMIP and pFlt3L compared to ALT alone (b, <i>P</i> = 0.03). (D), Eosinophil recruitment to the site of infection, the pleural cavity. Cell enumerations were performed on pleural lavage fluid. (E), Parasite survival represented as the proportion of worms found in the pleural cavity of infected mice relative to the infective dose. Points represent individual mice at D10 p.i. (N = 5–6 mice per group).</p