Contemporary nutrition-based interventions to reduce risk of infection among elderly long-term care residents: A scoping review.

BACKGROUND: Elderly long-term care residents (ELTCRs) face considerable burden of infection, especially evident during the COVID-19 pandemic. The nutritional status of the host can influence susceptibility to infection by altering immune system integrity, therefore, nutrition-based interventions may be a viable complement to existing infection prevention measures. OBJECTIVE: This scoping review sought to identify nutritional interventions and factors that have the strongest evidence to benefit ELTCRs, and thus best poised for rigorous clinical trial evaluation and subsequent implementation. METHODS: A database search of OVID-Medline, OVID-Embase, and Web of Science was performed from 2011 to 2021 to identify nutritional intervention studies which attribute to changes in infection in contemporary ELTCR settings. Articles were screened in duplicate and data extraction completed by a single reviewer, while a second reviewer verified the data which was fitted to identify evidence for nutritional interventions related to reducing rates of infection among ELTCRs. RESULTS: The search identified 1018 studies, of which 11 (nine clinical trials and two observational cohort studies) satisfied screening criteria. Interventions that significantly reduced risk of infection included whey protein (any infection), Black Chokeberry (urinary tract infection), and vitamin D (acute respiratory tract infection, skin and soft tissue infection). Both zinc and a dedicated meal-plan significantly improved lymphocyte parameters. Vitamin D deficiency was associated with the development of respiratory tract infections. Probiotic and soy-based protein interventions did not significantly affect risk of infection or lymphocyte parameters, respectively. CONCLUSION: The current scoping review was effective in identifying the use of nutrition-based interventions for infection prevention among ELTCRs. In this study, some nutrition-based interventions were observed to significantly influence the risk of infection among ELTCRs. Nutritional interventions such as vitamin D (preventing deficiency/insufficiency), Black Chokeberry juice, zinc gluconate, whey protein, and varied and nutrient dense meal plans may be suitable for future rigorous clinical trial evaluation.

"Every One of Us Is a Strand in That Basket": Weaving Together Stories of Indigenous Wellness and Resilience From the Perspective of Those With Lived and Living Experience With HIV/Hepatitis C Virus.

ABSTRACT: This article primarily focuses on the stories shared by Indigenous women with living and/or lived experiences of HIV/hepatitis C virus from the Vancouver Downtown East Side who attended the "Awakening our Wisdom" retreat. Weaving together the story of an Indigenous approach to research that informed the design of the retreat and the findings that emerged, a basket is formed that highlights the ways settler-colonialism within Canada has produced a system of health care that has neglected the Indigenous experience. The emerging themes of Connection, Disconnection, and Reconnection offers teachings for Indigenous journeys of resilience and wellness for those living with HIV/hepatitis C virus. These findings may help health care practitioners identify health care places and spaces that are in need of decolonization and offer, from an Indigenous perspective, the next steps forward for a health care system that promotes Indigenous engagement and retention in care.

Summary of an environmental scan of HIV and Hepatitis C programs, projects and initiatives in Saskatchewan.

Background: In 2019, the human immunodeficiency virus (HIV) and hepatitis C (HCV) diagnosis rates in Saskatchewan (SK) were approximately twice the national rate. To address these high levels, Saskatchewan Stories, a community-based digital database, was developed to make information on Saskatchewan-based HIV and HCV programs, projects and initiatives (PPI) centrally and freely available. To begin populating this database, we conducted an environmental scan representing HIV and HCV PPI from January 1, 1980 to May 31, 2020. Methods: MedLine, ERIC, ProQuest One Literature, Public Health Information database, SCOPUS and CINAHL were searched for both HIV and HCV articles. In addition, Bibliography of Native North Americans was searched for HIV and EMBSE (Ovid) and Indigenous studies portal (iPortal) were searched for HCV articles. Google Canada, Government of Saskatchewan, and Government of Canada websites were also searched. Results: In total, 139 HIV-specific PPI and 29 HCV-specific PPI were found in the environmental scan (n=168). Among HIV PPI, 27% (n=38) were from academic literature while 73% (n=101) were from grey literature. Among HCV PPI, 41% (n=12) were from academic literature, while 59% (n=17) were from grey literature. HIV accounted for 83% of total PPI, compared to 17% for HCV. Conclusion: This environmental scan is an important contribution to evidence-based practice and research in SK. It is particularly useful for organizations, researchers, policymakers and people living with HIV/HCV to develop new evidence-based PPI, to secure funding for PPI and to support individuals and communities in SK affected by HIV and HCV.

An environmental scan of impacts and interventions for women with methamphetamine use in pregnancy and their children.

BACKGROUND: Indigenous women are overrepresented among people who use (PWU) methamphetamine (MA) due to colonialism and intergenerational trauma. Prenatal methamphetamine exposure (PME) is increasing as the number of PWUMA of childbearing age grows. Yet impacts of MA in pregnancy and effective interventions are not yet well understood. OBJECTIVE: We conducted an environmental scan of published and grey literature (2010-2020) to determine effects of MA use in pregnancy for mothers and their offspring, effective interventions and implications for Indigenous women. SEARCH STRATEGY: A strategic search of Ovid Medline, Embase, ProQuest-Public Health and CINAHL databases identified academic literature, while Google and ProQuest-Public Health identified grey literature. SELECTION CRITERIA: Article selection was based on titles, abstracts and keywords. The time frame captured recent MA composition and excluded literature impacted by coronavirus disease 2019. DATA COLLECTION AND ANALYSIS: Data extracted from 80 articles identified 463 results related to 210 outcomes, and seven interventions. Analysis focused on six categories: maternal, neonatal/infant, cognitive, behavioral, neurological, and interventions. MAIN RESULTS: Maternal outcomes were more congruent than child outcomes. The most prevalent outcomes were general neonatal/infant outcomes. CONCLUSION: A lack of Indigenous-specific research on PME and interventions highlights a need for future research that incorporates relevant historical and sociocultural contexts.

Video Modeling and Video Feedback to Reduce Time to Perform Intravenous Cannulation in Medical Students: A Randomized-Controlled Mixed-Methods Study.

PURPOSE: Combined video modeling (VM) and video feedback (VF) may be more beneficial than traditional feedback when teaching procedural skills. This study examined whether repeated VM and VF compared with VM alone reduced the time required for medical students to perform peripheral intravenous (IV) cannulation. METHODS: Twenty-five novice medical students were randomly assigned to groups in a one-way blinded embedded mixed-methods study to perform IV cannulation. Participants received standardized instruction and performed IV cannulation on each other while being audio-video recorded. They were assigned to review a video of an expert performing IV cannulation (VM alone), or both the expert video and a video of their own most recent IV cannulation (VM+VF), before returning to perform another IV cannulation. This was repeated for a total of four IV cannulation encounters and three video reviews. A post-test interview was also conducted and analyzed qualitatively using thematic content analysis. RESULTS: The median [interquartile range] time required to perform IV cannulation in the final encounter was significantly different between the VM+VF group vs VM alone group (126 [93-226] sec vs 345 [131-537] sec, respectively; median difference, 111 sec; 95% confidence interval, 8 to 391; P = 0.02). There was no significant difference in IV cannulation success between VM alone and VM+VF in the final encounter (75% vs 85% respectively; P = 0.65). For the VM+VF group, the time to perform IV cannulation was reduced after the final encounter compared with the baseline encounter (P = 0.002), which was not true of the VM alone group (P = 0.35). CONCLUSION: Video modeling and feedback shortened time to IV skill completion, reduced complications, and improved satisfaction in novice medical students.

RéSUMé: OBJECTIF: La combinaison d'une vidéo de démonstration (VD) et d'une vidéo de rétroaction (VR) pourrait être plus efficace que la rétroaction traditionnelle pour l'enseignement des habiletés nécessaires pour des procédures. Cette étude a cherché à savoir si la répétition d'une VD et d'une VR réduisait davantage le temps nécessaire à des étudiants en médecine pour effectuer une canulation intraveineuse périphérique (IV) par rapport à la seule VD. MéTHODES: Vingt-cinq étudiants en médecine novices ont été assignés par randomisation à des groupes d'une étude utilisant différentes méthodes intégrées d'apprentissage avec insu unilatéral pour la réalisation d'une canulation IV. Les participants ont reçu un enseignement standardisé et ont réalisé une canulation IV sur un autre participant tout en étant filmés (audio-vidéo). Selon leur groupe, ils devaient visionner la vidéo d'un expert effectuant une canulation IV (groupe VD uniquement) ou voir la vidéo de l'expert et une vidéo de leur plus récente canulation IV (groupe VD + VR) avant d'effectuer une autre canulation IV. La procédure a été répétée (total de 4 tentatives de canulations et 3 séances de vidéos). Un entretien post test a été également mené et analysé du point de vue qualitatif au moyen d'une analyse thématique du contenu. RéSULTATS: Le temps médian [plage interquartile] nécessaire pour effectuer la canulation IV au cours de la dernière tentative a été significativement différent entre le groupe VD+VR et le groupe VD seule (respectivement, 126 secondes [93 à 226 s] contre 345 s [131 à 537 s]; différence des médianes, 111 s; intervalle de confiance à 95 % : 8 à 391; P = 0,02). Il n'y a pas eu de différence significative entre le taux de réussite des canulations entre le groupe VD seule et le groupe VD+VR (respectivement, 75 % contre 85 %; P = 0,65). Pour le groupe VD+VR, le temps nécessaire à la canulation IV au moment de la dernière tentative a été plus court par rapport au temps mis au cours de la première tentative (P = 0,002), ce qui n'a pas été le cas pour le groupe VD seule (P = 0,35). CONCLUSION: La vidéo de démonstration et la vidéo de rétroaction ont permis de raccourcir le temps de réalisation des habiletés d'une canulation IV, ont réduit les complications et amélioré la satisfaction des étudiants en médecine novices.

Risk Factors Associated with Self-reported Sexually Transmitted Infections among Postsecondary Students in Canada.

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.

Cattle Immunized with a Recombinant Subunit Vaccine Formulation Exhibits a Trend towards Protection against Histophilus somni Bacterial Challenge.

Histophilosis, a mucosal and septicemic infection of cattle is caused by the Gram negative pathogen Histophilus somni (H. somni). As existing vaccines against H. somni infection have shown to be of limited efficacy, we used a reverse vaccinology approach to identify new vaccine candidates. Three groups (B, C, D) of cattle were immunized with subunit vaccines and a control group (group A) was vaccinated with adjuvant alone. All four groups were challenged with H. somni. The results demonstrate that there was no significant difference in clinical signs, joint lesions, weight change or rectal temperature between any of the vaccinated groups (B,C,D) vs the control group A. However, the trend to protection was greatest for group C vaccinates. The group C vaccine was a pool of six recombinant proteins. Serum antibody responses determined using ELISA showed significantly higher titers for group C, with P values ranging from < 0.0148 to < 0.0002, than group A. Even though serum antibody titers in group B (5 out of 6 antigens) and group D were significantly higher compared to group A, they exerted less of a trend towards protection. In conclusion, the vaccine used in group C exhibits a trend towards protective immunity in cattle and would be a good candidate for further analysis to determine which proteins were responsible for the trend towards protection.

Reverse vaccinology as an approach for developing Histophilus somni vaccine candidates.

Histophilosis of cattle is caused by the Gram negative bacterial pathogen Histophilus somni (H. somni) which is also associated with the bovine respiratory disease (BRD) complex. Existing vaccines for H. somni include either killed cells or bacteria-free outer membrane proteins from the organism which have proven to be moderately successful. In this study, reverse vaccinology was used to predict potential H. somni vaccine candidates from genome sequences. In turn, these may protect animals against new strains circulating in the field. Whole genome sequencing of six recent clinical H. somni isolates was performed using an Illumina MiSeq and compared to six genomes from the 1980's. De novo assembly of crude whole genomes was completed using Geneious 6.1.7. Protein coding regions was predicted using Glimmer3. Scores from multiple web-based programs were utilized to evaluate the antigenicity of these predicted proteins which were finally ranked based on their surface exposure scores. A single new strain was selected for future vaccine development based on conservation of the protein candidates among all 12 isolates. A positive signal with convalescent serum for these antigens in western blots indicates in vivo recognition. In order to test the protective capacity of these antigens bovine animal trials are ongoing.

Single nucleotide polymorphisms in the bovine Histophilus somni genome; a comparison of new and old isolates.

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.

Histophilus somni est l'un des agents majeurs du complexe respiratoire bovin (CRB), qui peut aussi causer diverses pathologies dont de la bronchopneumonie, myocardite, péricardite, arthrite, pleurésie et de la méningo-encéphalite thrombotique. L'objectif général de l'étude était de comparer les souches actuellement en circulation avec les souches isolées dans les années 80. Plus spécifiquement les changements génétiques survenus entre des isolats récents et des isolats collectés il y a une trentaine d'années ont été analysés. Les polymorphismes d'un seul nucléotide (single nucleotide polymorphism, SNP) ont été examinés en utilisant une approche de séquençage global de tout le génome pour 12 échantillons, six anciens et six nouveaux. Un total de 31 028 SNPs a été identifié et une analyse comparative de ces SNPs avec la séquence génomique de référence de la souche pathogène 2336 de H. somni a été effectuée. La distribution génique d'environ 75 % de ces SNPs entre les souches anciennes et récentes est différente et ne suit pas de tendance particulière. Toutefois, 25 % des SNPs se répartissent rapidement en deux groupes distincts. Le groupe I inclut cinq isolats anciens et un récent alors que le groupe II comprend cinq isolats récents et un isolat ancien qui se regroupent ensemble pour de mêmes SNPs dans plusieurs gènes. La présence des SNPs dans des gènes potentiellement liés à la virulence est plus manifeste dans le groupe I, comparé à l'ancien isolat 2336, que dans le groupe II. Bien que seulement 25 % des SNPs totaux se répartissent en deux groupes, les résultats suggèrent des variations génétiques significatives entre souches anciennes et récentes dans les séquences de nombreux gènes.(Traduit par Docteur François Meurens).

Safety, specificity and immunogenicity of a PrP(Sc)-specific prion vaccine based on the YYR disease specific epitope.

Prions are a novel form of infectivity based on the misfolding of a self-protein (PrP(C)) into a pathological, infectious isomer (PrP(Sc)). The current uncontrolled spread of chronic wasting disease in cervids, coupled with the demonstrated zoonotic nature of select livestock prion diseases, highlights the urgent need for disease management tools. While there is proof-of-principle evidence for a prion vaccine, these efforts are complicated by the challenges and risks associated with induction of immune responses to a self-protein. Our priority is to develop a PrP(Sc)-specific prion vaccine based on epitopes that are uniquely exposed upon misfolding. These disease specific epitopes (DSEs) have the potential to enable specific targeting of the pathological species through immunotherapy. Here we review outcomes of the translation of a prion DSE into a PrP(Sc)-specific vaccine based on the criteria of immunogenicity, safety and specificity.

Binding of bovine T194A PrP(C) by PrP(Sc)-specific antibodies: potential implications for immunotherapy of familial prion diseases.

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 reveals differences in structural stability of ovine PrP(C) proteins corresponding to scrapie susceptible (VRQ) and resistance (ARR) genotypes.

Species, as well as individuals within species, have unique susceptibilities to prion infection that are likely based on sequence differences in cellular prion protein (PrP(C)). Species barriers to transmission also reflect PrP(C) sequence differences. Defining the structure-activity relationship of PrP(C)/PrP(Sc) with respect to infectivity/susceptibility will benefit disease understanding and assessment of transmission risks. Here, nanopore analysis is employed to investigate genotypes of sheep PrP(C) corresponding to differential susceptibilities to scrapie infection. Under non-denaturing conditions scrapie resistant (ARR) and susceptible (VRQ) genotypes display similar, type I (bumping) predominant event profiles, suggesting a conserved folding pattern. Under increasingly denaturing conditions both proteins shift to type II (intercalation/translocation) events but with different sensitivities to unfolding. Specifically, when pre-incubated in 2M Gdn-HCl, the VRQ variant had more of type II events as compared with the ARR protein, suggesting a more flexible unfolding pattern. Addition of PrP(Sc)-specific polyclonal antibody (YML) to the ARR variant, pre-incubated in 2M Gdn-HCl, reduced the number of type II events with no clear intercalation/translocation peak, whereas for VRQ, type II events above blockades of 90 pA bound YML. A second PrP(Sc)-specific antibody (SN6b) to a different cryptic epitope reduced type II events for VRQ but not the ARR variant. Collectively, the event patterns associated with sequential denaturation, as well as interactions with PrP(Sc)-specific antibodies, support unique patterns and/or propensities of misfolding between the genotypes. Overall, nanopore analysis identifies intermediate conformations that occur during the unfolding pathways of ARR and VRQ genotypes and may help to understand the correlation of structural properties that induce protein misfolding.

Nanopore analysis: An emerging technique for studying the folding and misfolding of proteins.

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) Aß 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.

Nanopore analysis of tethered peptides.

Peptides of 12 amino acids were tethered via a terminal cysteine to mono-, di-, tri-, and tetrabromomethyl-substituted benzene to produce bundles of one to four peptide strands (CY12-T1 to CY12-T4, respectively). The interaction of the bundles with the α-hemolysin pore was assessed by measuring the blockade currents (I) and times (T) at an applied potential of - 50, - 100, and - 150 mV. Three types of events could be distinguished: bumping events, with small I and short T where the molecule transiently interacts with the pore before diffusing away; translocation events, where the molecule threads through the pore with large I and the value of T decreases with increasing voltage; and intercalation events, where the molecule transiently enters the pore but does not translocate with large I and the value of T increases with increasing voltage. CY12-T1 and CY12-T2 gave only bumping and translocation events; CY12-T3 and CY12-T4 also gave intercalation events, some of which were of very long duration. The results suggest that three uncoiled peptide strands cannot simultaneously thread through the α-hemolysin pore and that proteins must completely unfold in order to translocate.

Nanopore analysis of the interaction of metal ions with prion proteins and peptides.

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)2 and Octa 4, (PHGGGWGQ)4), residues 106-126 (PrP106-126), and the full-length Bovine recombinant prion (BrecPrP) were studied with an alpha-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.

Nanopore detection of antibody prion interactions.

In nanopore analysis, peptides and proteins can be detected by the change in current when single molecules interact with an alpha-hemolysin pore embedded in a lipid membrane. A prion peptide, PrP(143-169), can readily translocate through the pore, but on the addition of monoclonal antibody M2188, which binds the peptide, the number of translocations is reduced because the complex is too large to translocate. At a peptide-to-immunoglobulin G (IgG) ratio of 2:1, only bumping events were observed. The event profile of a control peptide that does not bind the antibody was unchanged. Similarly, the presence of the antibody prevents translocation of the full-length prion protein. Because a nanopore can detect a single molecule, these experiments represent an important first step towards the development of a sensitive prion detector.