Characterization of S3Pvac Anti-Cysticercosis Vaccine Components: Implications for the Development of an Anti-Cestodiasis Vaccine

Background: Cysticercosis and hydatidosis seriously affect human health and are responsible for considerable economic loss in animal husbandry in non-developed and developed countries. S3Pvac and EG95 are the only field trial-tested vaccine candidates against cysticercosis and hydatidosis, respectively. S3Pvac is composed of three peptides (KETc1, GK1 and KETc12), originally identified in a Taenia crassiceps cDNA library. S3Pvac synthetically and recombinantly expressed is effective against experimentally and naturally acquired cysticercosis.Methodology/ Principal Findings: In this study, the homologous sequences of two of the S3Pvac peptides, GK1 and KETc1, were identified and further characterized in Taenia crassiceps WFU, Taenia solium, Taenia saginata, Echinococcus granulosus and Echinococcus multilocularis. Comparisons of the nucleotide and amino acid sequences coding for KETc1 and GK1 revealed significant homologies in these species. The predicted secondary structure of GK1 is almost identical between the species, while some differences were observed in the C terminal region of KETc1 according to 3D modeling. A KETc1 variant with a deletion of three C-terminal amino acids protected to the same extent against experimental murine cysticercosis as the entire peptide. on the contrary, immunization with the truncated GK1 failed to induce protection. Immunolocalization studies revealed the non stage-specificity of the two S3Pvac epitopes and their persistence in the larval tegument of all species and in Taenia adult tapeworms.Conclusions/ Significance: These results indicate that GK1 and KETc1 may be considered candidates to be included in the formulation of a multivalent and multistage vaccine against these cestodiases because of their enhancing effects on other available vaccine candidates

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Time-dependent gas dynamics and gas-particle heat and mass transfer during plasma spray deposition

This paper describes a time-dependent and 3-D computer model of the atmosphere pressure plasma spray process. The model uses a two-step procedure. The first deals with the formation of the primary plasma jet inside the plasma torch and solves simultaneously the time-dependent NavierStokes\ud equations, conservation equation of electric current and electromagnetism equations assuming that the electromagnetism phenomena are quasi-steady. The second involves the discharge of the plasma jet in air and the heating and acceleration of the powder particles. It is\ud based on the momentum and thermal energy equations for a three components (plasma forming gas, powder carrier gas and air) gas mixture, continuity equations for each component of the mixture and state relation. The particle model uses a stochastic and time-dependent injection description with a distribution of particle size, injection velocity and injection direction in three dimensions. Once the particles exit the injector; their acceleration, heating and vaporization are calculated with a Lagrangian scheme. Their trajectory and velocity are determined from a balance of the gravity, Archimedean, pressure gradient and drag forces. Particles are subjected to turbulent dispersion with the assumption that the turbulent eddies have random lifetimes. The temperature evolution of\ud particles along their trajectory is calculated from a heat flux balance in the boundary layer surrounding the particles. Such a model provides physical insight on phenomena that cannot be easily measured directly as the flow fields inside the plasma torch and the time-variation of the flow characteristics and particle behaviour

MOLECULAR SYSTEMATICS OF \u3ci\u3eMESOCESTOIDES\u3c/i\u3e SPP. (CESTODA: MESOCESTOIDIDAE) FROM DOMESTIC DOGS (\u3ci\u3eCANIS FAMILIARIS\u3c/i\u3e) AND COYOTES (\u3ci\u3eCANIS LATRANS\u3c/i\u3e)

The genus Mesocestoides Vaillant, 1863 includes tapeworms of uncertain phylogenetic affinities and with poorly defined life histories. We previously documented 11 cases of peritoneal cestodiasis in dogs (Canis familiaris L.) in western North America caused by metacestodes of Mesocestoides spp. In the current study, DNA sequences were obtained from metacestodes collected from these dogs (n = 10), as well as proglottids from dogs (n = 3) and coyotes (Canis latrans Say, 1823 [n = 2]), and tetrathyridia representing laboratory isolates of M. corti (n = 3), and these data were analyzed phylogenetically. Two nuclear genetic markers, 18S ribosomal DNA and the second internal-transcribed spacer (ITS 2), were sequenced. Phylogenetic analysis of the 18S rDNA data recovered a monophyletic group composed of all samples of Mesocestoides spp., distinct from closely related outgroup taxa (Amurotaenia Akhmerov, 1941 and Tetrabothrius Rudolphi, 1819). Initial analysis of the ITS 2 data resolved 3 clades within Mesocestoides. Two proglottids from dogs formed a basal clade, a second clade was represented by tetrathyridial isolates, and a third clade included all other samples. Interpretation of these data from an apomorphy-based perspective identified 6 evolutionary lineages. We also assessed whether metacestodes from dogs (n = 4) are capable of asexual proliferation in laboratory mice. One tetrathyridial and 2 acephalic isolates from dogs proliferated asexually. Further investigation is warranted to determine which of the lineages represent distinct species and to determine the life history strategies of Mesocestoides spp