Plant virus particles carrying tumour antigen activate TLR7 and induce high levels of protective antibody

Induction of potent antibody is the goal of many vaccines targeted against infections or cancer. Modern vaccine designs that use virus-like particles (VLP) have shown efficacy for prophylactic vaccination against virus-associated cancer in the clinic. Here we used plant viral particles (PVP), which are structurally analogous to VLP, coupled to a weak idiotypic (Id) tumour antigen, as a conjugate vaccine to induce antibody against a murine B-cell malignancy. The Id-PVP vaccine incorporates a natural adjuvant, the viral ssRNA, which acts via TLR7. It induced potent protective anti-Id antibody responses in an in vivo mouse model, superior to the "gold standard" Id vaccine, with prevalence of the IgG2a isotype. Combination with alum further increased antibody levels and maintained the IgG2a bias. Engagement of TLR7 in vivo was followed by secretion of IFN-? by plasmacytoid dendritic cells and by activation of splenic CD11chi conventional dendritic cells. The latter was apparent from up-regulation of co-stimulatory molecules and from secretion of a wide range of inflammatory cytokines and chemokines including the Th1-governing cytokine IL-12, in keeping with the IgG2a antibody isotype distribution. PVP conjugates are a novel cancer vaccine design, offering an attractive molecular form, similar to VLP, and providing T-cell help. In contrast to VLP, they also incorporate a safe "in-built" ssRNA adjuvant

Metody i techniki molekularne stosowane w diagnostyce i epidemiologii zakazen grzybami chorobotworczymi

Molecular method B and techniques used in diagnosis and epidemiology or infections caused by pathogenic fungi. In this paper we reviewed the latest literature on molecular techniques used in diagnosis and epidemiology of infections caused by pathogenic fungi. Traditional methods used for the identification and typing of medically relevant fungi include morphological and biochemical analysis. These methods are time-consuming and base on phenotypic features what makes them unreliable. We described the usefulness in mycological studies of fast and very sensitive molecujar methods which rely on PCR and hybridization techniques

SOS repair and DNA supercoiling influence the genetic stability of DNA triplet repeats in Escherichia coli

Molecular mechanisms responsible for the genetic instability of DNA trinucleotide sequences (TRS) account for at least 20 human hereditary disorders. Many aspects of DNA metabolism influence the frequency of length changes in such repeats. Herein, we demonstrate that expression of Escherichia coli SOS repair proteins dramatically decreases the genetic stability of long (CTG/CAG)n tracts contained in plasmids. Furthermore, the growth characteristics of the bacteria are affected by the (CTG/CAG)n tract, with the effect dependent on the length of the TRS. In an E. coli host strain with constitutive expression of the SOS regulon, the frequency of deletions to the repeat is substantially higher than that in a strain with no SOS response. Analyses of the topology of reporter plasmids isolated from the SOS+ and SOS– strains revealed higher levels of negative supercoiling in strains with the constitutively expressed SOS network. Hence, we used strains with mutations in topoisomerases to examine the effect of DNA topology upon the TRS instability. Higher levels of negative DNA supercoiling correlated with increased deletions in long (CTG/CAG)n, (CGG/CCG)n and (GAA/TTC)n. These observations suggest a link between the induction of bacterial SOS repair, changes in DNA topology and the mechanisms leading to genetic instability of repetitive DNA sequences

Compression and self-entanglement of single DNA molecules under uniform electric field

We experimentally study the effects of a uniform electric field on the conformation of single DNA molecules. We demonstrate that a moderate electric field (~200 V/cm) strongly compresses isolated DNA polymer coils into isotropic globules. Insight into the nature of these compressed states is gained by following the expansion of the molecules back to equilibrium after halting the electric field. We observe two distinct types of expansion modes: a continuous molecular expansion analogous to a compressed spring expanding, and a much slower expansion characterized by two long-lived metastable states. Fluorescence microscopy and stretching experiments reveal that the metastable states are the result of intramolecular self-entanglements induced by the electric field. These results have broad importance in DNA separations and single molecule genomics, polymer rheology, and DNA-based nanofabrication.National Science Foundation (U.S.) (grant CBET-0852235)Singapore-MIT Alliance for Research and Technolog