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Introduction An increasing number of neurodegenerative diseases can be attributed to the misfolding of proteins. For example, the amyloid precursor protein is implicated in Alzheimer's, α-synuclein in Parkinson's, superoxide dismutase [...], Nanopore analysis can be used to study conformational changes in individual peptide or protein molecules. Under an applied voltage there is a change in the event parameters of blockade current or time when a molecule bumps into or translocates through the pore. If a molecule undergoes a conformational change upon binding a ligand or metal ion the event parameters will be altered. The objective of this research was to demonstrate that the conformation of the prion protein (PrP) and prion peptides can be modulated by binding divalent metal ions. Peptides from the octarepeat region (Octa2, [(PHGGGWGQ).sub.2] and Octa 4, [(PHGGGWGQ).sub.4]), residues 106-126 (PrP106-126), and the full-length Bovine recombinant prion (BrecPrP) were studied with an α-hemolysin pore. Octa2 readily translocated the pore but significant bumping events occurred on addition of Cu(II) and to a lesser extent Zn(II), demonstrating that complex formation was occurring with concomitant conformational changes. The binding of Cu(II) to Octa4 was more pronounced and at high concentrations only a small proportion of the complex could translocate. Addition of Zn(II) also caused significant changes to the event parameters but Mg(II) and Mn(II) were inert. Addition of Cu(II) to PrP106-126 caused the formation of a very tight complex, which could not translocate the pore. Small changes were observed with Zn(II), but not with Mg(II) or Mn(II). Analysis of BrecPrP showed that about 37% were translocation events, but on addition of Cu(II) or Zn(II) these disappeared and only bumping events were recorded. Suprisingly, addition of Mn(II) caused an increase in translocation events to about 64%. Thus, conformational changes to prions upon binding metal ions are readily observed by nanopore analysis. Key words: prion protein, protein folding, metal ion binding, nanopores, α-hemolysin. L'analyse par nanopore peut etre utilisee pour etudier les changements de conformation d'un peptide ou d'une proteine individuels. L'application d'un voltage induit un changement dans les evenements parametres du courant de blocage ou dutemps, lorsqu'une molecule frappe ou traverse un pore. Si une molecule subit un changement de conformation lors de la liaison d'un ligand ou d'un ion metallique, les evenements parametres seront modifies. L'objectif de cette recherche etait de demontrer que la conformation du prion PrP ou de peptides qui en sont derives peut etre modulee par la liaison d'ions metalliques divalents. Des peptides de la region des octapeptides repetes [Octa 2, [(PHGGGWGQ).sub.2] et Octa 4 [(PHGGGWGQ).sub.4]], un peptide comportant les residus 106-126 [PrP(106-126)] et la proteine bovine recombinante de pleine longueur [BrecPrP] ont ete etudies avec un pore d'α-hemolysine. Octa2 traversait facilement le pore mais un nombre significatif de collisions survenaient lors de l'ajout de Cu(II) et, dans une moindre mesure, de Zn(II), demontrant que la formation de complexes s'accompagnait de changements de conformation. La liaison de Cu(II) a Octa4 etait plus prononcee et a hautes concentrations, une petite proportion des complexes seulement pouvait traverser le pore. L'addition de Zn(II) causait des changements significatifs des evenements parametres mais le Mg(II) et le Mn(II) etaient inactifs. L'addition de Cu(II) a PrP(106-126) induisait la formation de complexes tres forts qui ne pouvaient pas traverser le pore. De petits changements ont ete observes avec le Zn(II) mais pas avec le Mg(II) et le Mn(II). L'analyse de BrecPrP montrait qu'environ 37% des evenements consistaient en des translocations mais qu'avec l'ajout de Cu(II) ou de Zn(II), elles disparaissaient completement et que seules des collisions etaient enregistrees. De facon surprenante, l'addition de Mn(II) induisait une augmentation des evenements de translocation a environ 64%. Ainsi, les changements de conformation du prion lors de la liaison d'ions metalliques etaient facilement observes par une analyse par nanopore. Mots-cles: prion, repliement des proteines, liaison d'ions metalliques, nanopores, α-hemolysine. [Traduit par la Redaction]

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Background: Despite major public health efforts in addressing the burden of disease caused by sexually transmitted infections (STIs), rates among young adults continue to rise in Canada. The purpose of the study was to examine the prevalence and risk factors associated with acquiring STIs among postsecondary students in Canada. Methods: A secondary analysis of the American College Health Association-National College Health Assessment II-C Spring 2016 survey data (n = 43,780) was conducted. Sexually active participants (n = 28,831) were examined for their demographics, sexual behavior, alcohol and marijuana use, testing for human immunodeficiency virus (HIV), and human papillomavirus vaccination history. These factors were analyzed to help identify their possible association with acquiring an STI using logistic regression and multivariate modeling. Results: Among the study participants, 3.88% had an STI, with the highest rates observed among females and individuals aged 21-24 years old. Multivariate logistic analysis showed that participants who engaged in anal intercourse within the past 30 days (odds ratio [OR] = 1.634; 95% confidence interval [CI], 1.343-1.988), had four or more sexual partners in the last 12 months (OR = 4.223; 95% CI, 3.595-4.962), used marijuana within the past 30 days (OR = 1.641; 95% CI, 1.387-1.941), and had ever been tested for HIV (OR = 3.008; 95% CI, 2.607-3.471) had greater odds of acquiring an STI. Conclusions: The findings of this study highlight certain high-risk behaviors that are strongly associated with acquiring an STI among postsecondary students. Thus, efforts to design and deliver relevant educational programming and health promotion initiatives for this particular population are of utmost importance. [ABSTRACT FROM AUTHOR]

Histophilus somni, a causative agent of the bovine respiratory disease complex, can also cause a variety of systemic disorders, including bronchopneumonia, myocarditis, pericarditis, arthritis, pleuritis, and infectious thrombotic meningoencephalitis. The purpose of this study was to determine if currently circulating strains differ from those of the 1980s by identifying genomic changes. Single nucleotide polymorphisms (SNPs) and insertion and deletion (INDEL) sites were examined by whole-genome sequencing in 12 samples, 6 old and 6 new. The 31 028 SNP/INDELs recorded were compared against the reference genome sequence of the pathogenic H. somni strain 2336. The distribution of about 75% of these SNPs within a specified gene differed between old and new isolates and did not follow any particular pattern. The other 25% clustered into 2 groups containing the same SNPs in various genes: group I included 5 old isolates and 1 new isolate; group II included 5 new isolates and 1 old isolate. For putative virulence genes there were more SNPs in group I compared with strain 2336, itself an older isolate, than in group II. Although only 25% of all the SNPs formed 2 clusters, the results suggest some genetic difference in various genes between old and new strains.

Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases that are based on the misfolding of a cellular prion protein (PrP(C)) into an infectious, pathological conformation (PrP(Sc)). There is proof-of-principle evidence that a prion vaccine is possible but this is tempered with concerns of the potential dangers associated with induction of immune responses to a widely-expressed self-protein. By targeting epitopes that are specifically exposed upon protein misfolding, our group developed a vaccine that induces PrP(Sc)-specific antibody responses. Here we consider the ability of this polyclonal antibody (SN6b) to bind to a mutant of PrP(C) associated with spontaneous prion disease. Polyclonal antibodies were selected to mimic the vaccination outcome and also explore all possible protein conformations of the recombinant bovine prion protein with mutation T194A [bPrP(T194A)]. This mutant is a homolog of the human T183A mutation of PrP(C) that is associated with early onset of familial dementia. With nanopore analysis, under non-denaturing conditions, we observed binding of the SN6b antibody to bPrP(T194A). This interaction was confirmed through ELISAs as well as immunoprecipitation of the recombinant and cellularly expressed forms of bPrP(T194A). This interaction did not promote formation of a protease resistant conformation of PrP in vitro. Collectively, these findings support the disease-specific approach for immunotherapy of prion diseases but also suggest that the concept of conformation-specific immunotherapy may be complicated in individuals who are genetically predisposed to PrP(C) misfolding.

Nanopore analysis is an emerging technique that enables the investigation of the conformation of a single peptide or protein molecule. Briefly, a pore is inserted into a membrane under voltage clamp conditions. When a molecule interacts with the pore there is a change in the current, I, for a time, T. Small unfolded molecules can translocate the pore whereas folded or large molecules tend to simply bump into the pore and then diffuse away. Therefore, the parameters, I and T, are dependent on the conformation of the molecule at the instant at which it encounters the pore. Thus, multiple conformations can be detected simultaneously in a single sample. As well, the analysis can be performed under dilute conditions so that folding or dimerization of a peptide can be followed in real time, which is generally difficult to study for proteins that are prone to aggregate. In this report, we describe our initial analysis of (1) Aβ peptides, which are deposited as amyloid plaques in Alzheimer disease, (2) α-synuclein, which is implicated in Parkinson disease and (3) prion proteins whose misfolding is evident in transmissable spongiform encephalopathies. In each case conformational information can be obtained which may help in understanding the early steps in the misfolding pathways.