ABSTRACT
This study aims to understand the roles of selected extension professionals (EPs) in the field of public health and One Health and the challenges involved in performing these duties to their communities in the state of Kansas. To evaluate the role of EPs in public health and One Health, researchers interviewed nine (9) EPs following a set of structured questions. Emerging themes were extrapolated from the responses of the EPs. Researchers assigned codes for qualitative analysis and assigned themes related to public health, One Health, and effective delivery of services. Researchers identified the following themes related to the role of EPs in public health (youth development, physical activity, personal health care, proper nutrition, access to transportation), One Health (food safety and food security, environmental health, disease control and prevention) and effective delivery of services (community engagement, collaboration, challenges in implementation). The study provided an overview of the diverse roles that EPs play in public health and One Health, keys on how to engage the community effectively, and challenges in extending services to the community.
Subject(s)
One Health , Public Health , Kansas , Humans , Professional RoleABSTRACT
(1) Background: Following the COVID-19 pandemic, vaccine hesitancy has become an increasingly important topic and has created significant concerns in public health. It is important to explore vaccine hesitancy among college students as they have been identified to be a high-risk group for COVID-19 transmission. This study aims to investigate COVID-19 vaccine hesitancy in college students on a midsized midwestern university campus. (2) Methods: Data were collected from 311 undergraduate and graduate college students during June and July 2021. Participants completed a survey on COVID-19 vaccine behaviors, perceptions, and opinions. Quantitative and qualitative analysis was performed to identify vaccine hesitancy and influencing factors in the student population. (3) Results: The results of this study demonstrated significant relationships between older and younger undergraduate students (OR > 1, p < 0.05), students who received a yearly influenza vaccine and those that did not (p < 0.05), and students who had a previous COVID-19 infection and those that did not (OR > 1, p < 0.05). We also determined a significant difference between some racial/ethnic groups and vaccine hesitancy status. (4) Conclusions: COVID-19 vaccine hesitancy exists on college campuses, and is influenced by age and student status, influenza vaccination status, previous COVID-19 infection, and race/ethnicity.
ABSTRACT
This study evaluates the success of secondary public health education in enhancing a professional degree in veterinary medicine. Dual-degree programs promote multidisciplinary skill attainment crucial to succeed in today's One Health-centered veterinary workforce. Participant demographics were collected including academic background, dual-degree enrollment status, and intended course of study. Survey data were collected from both Master of Public Health students and dual Doctor of Veterinary Medicine/Master of Public Health students. To measure knowledge attainment, students over a 10-year period were provided core competency and program perception-based surveys upon entering and exiting the public health program. Participants were asked to rate their knowledge of competencies based on a scale of having "no knowledge" to being "very knowledgeable." Program perceptions were reported through multiple response types. Open-ended response questions evaluated participants' perceived program success in aiding the development of professional veterinary public health knowledge. The dual nature of this degree program is hypothesized to enhance interprofessional capabilities for those entering the field of veterinary medicine. A qualitative thematic comparison of participants' entrance and exit survey responses indicated increased levels of concern for career preparation services in dual-degree students. By coursework completion, students' most valued competencies were related to epidemiology, biostatistics, and behavioral health. Quantitative analysis revealed that students concurrently enrolled in a veterinary and public health program demonstrate significantly higher levels of self-reported knowledge relating to disease measurement, ethical and legal principles, and epidemiological data interpretation. Students with educational backgrounds in veterinary and animal sciences demonstrated significantly higher levels of program satisfaction.
ABSTRACT
Public health and healthcare professionals perform a wide variety of services for their communities, and serve in important and often overlapping roles, particularly in rural communities. In this qualitative study, public health practitioners in Kansas were asked about their perceptions of barriers to public health and vulnerable people in their communities. Participants from across Kansas were interviewed via teleconferencing, telephone, or email, and emergent themes were identified using qualitative thematic analysis. While asked about public health specifically, during interviews, many participants discussed barriers to healthcare as well. The top barriers to effective public health practice identified in this study were funding, education, accessibility, and affordability. Others included politics, transportation, and the need to expand Medicare and Medicaid. The populations believed most vulnerable in their communities were community members living in poverty, elderly people, and other marginalized populations. Our findings suggest public health practitioners in Kansas observe a lack of understanding and knowledge in their communities about public health, along with the recognition that a lack of accessibility and affordability to health services are barriers to effective public health practice.
Subject(s)
Medicare , Rural Population , Aged , Health Services Accessibility , Humans , Kansas , Public Health Practice , Qualitative Research , United StatesABSTRACT
OBJECTIVE: To partner with and understand the health of Somali Bantu refugee women, small group sessions were designed and conducted using a community-based collaborative action research (CBCAR) approach. Health topics identified by this community were presented in 42 sessions with eleven women. Follow-up individual interviews with the women were used to ask questions about health experiences and plan for future health education. The objective of this qualitative study was to provide refugee women with knowledge to help them adjust to new health challenges in the United States, and to share personal narratives in a safe environment. RESULTS: The process of sharing health information with the women resulted in a collaborative exchange of culture and community. Individual interviews allowed women to voice their opinions outside of the influence of their community elders. CBCAR is an effective tool to involve refugee communities, and other populations small in number, in addressing their unique health challenges. Results from this study demonstrated that small group sessions and a CBCAR approach can be effective in sharing knowledge within small communities of refugee women. Findings from the study will assist in the future planning of health education programs for refugee women and their families in this community.
Subject(s)
Culturally Competent Care/methods , Health Education/ethics , Refugees/psychology , Adult , Community-Based Participatory Research/methods , Culturally Competent Care/ethics , Female , Health Knowledge, Attitudes, Practice , Humans , Kansas , Qualitative Research , Somalia , United StatesABSTRACT
OBJECTIVE: To explore the process of partnership between university researchers, students, and South Sudanese refugee women to address the health challenges associated with their resettlement transition to the United States. DESIGN AND SAMPLE: This qualitative study used a community-based collaborative action research (CBCAR) framework in the design, collection, and analysis of the qualitative data. Twenty refugee women participated in this study. INTERVENTION: Five health education seminars followed by an audio-recorded focus group were held over 9 months. A final focus group was held to confirm derived themes and develop an action plan. RESULTS: The partnership between the refugee women and researchers resulted in awareness of how power structures and differing expectations affected the process. The dialog in the focus groups provided an opportunity for refugee women to voice challenges to their health in resettlement. A pattern was recognized about how political and sociocultural events affected the process of CBCAR. Dialog and sharing differing worldviews and perspectives led to insights about ways to improve the health of the South Sudanese refugee community. CONCLUSIONS: CBCAR is a useful framework to address health concerns of a refugee community. Insights from this study provided a foundation for a future intervention research project with the refugee women.
Subject(s)
Community-Based Participatory Research/organization & administration , Cooperative Behavior , Health Services Research/organization & administration , Refugees/psychology , Adult , Female , Focus Groups , Humans , Qualitative Research , Refugees/statistics & numerical data , South Sudan/ethnology , United StatesABSTRACT
The Vif protein of human immunodeficiency virus-1 (HIV-1) has been shown to interact with members of the APOBEC family of cytidine deaminases, particularly APOBEC3G/F. In this study, we isolated RNA from 12 regions of the brain from two pigtailed macaques that were exsanguinated and perfused with saline. Our results indicate that APOBEC3G was detected in all regions of the brain analyzed. Immunoblot analysis using lysates prepared from these same regions of the brain and a monoclonal antibody to APOBEC3G confirmed the RT-PCR findings. To determine which cell types express APOBEC3G, immunohistochemical studies were performed using this monoclonal antibody on whole brain sections. Our results clearly show that the pyramidal neurons within the gray matter of cerebral and cerebellar cortices express APOBEC3G. However, APOBEC3G expression in the pyramidal neurons appeared to be nuclear or associated with nuclei. In contrast to our findings in the cerebral cortex, immunohistochemical analysis of the spleen and kidney tissues revealed that APOBEC3G expression in the cells of these tissues was predominantly cytoplasmic. We further investigated the expression of APOBEC3G in astrocytes. Immunohistochemical staining of serial sections was performed using antibodies to glial fibrillary acidic protein (GFAP) and APOBEC3G. As expected, the cortical and cerebellar white matter showed extensive immunostaining of astrocytes with the antibody against GFAP but a lack of reactivity to the antibody to APOBEC3G. Additionally, Immunoblot analysis of lysates prepared from primary human fetal astrocytes revealed a lack of APOBEC3G expression. Taken together, these results indicate that APOBEC3G expression is restricted to neurons in the brain and that astrocytes and microglia probably do not express this protein or express it at levels undetectable by immunohistochemistry. These finding have implications for the brain as a potential reservoir for Vif-defective viruses.
Subject(s)
Cytidine Deaminase/metabolism , Neurons/metabolism , APOBEC-3G Deaminase , Animals , Cytidine Deaminase/genetics , Humans , Immunoblotting , Immunohistochemistry , Macaca nemestrina , Mice , Nucleoside Deaminases/genetics , Nucleoside Deaminases/metabolism , Rats , Repressor Proteins/genetics , Repressor Proteins/metabolism , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The Vpu protein of human immunodeficiency virus type 1 has been shown to shunt the CD4 receptor molecule to the proteasome for degradation and to enhance virus release from infected cells. The exact mechanism by which the Vpu protein enhances virus release is currently unknown but some investigators have shown that this function is associated with the transmembrane domain and potential ion channel properties. In this study, we determined if the transmembrane domain of Vpu could be functionally substituted with that of the prototypical viroporin, the M2 protein of influenza A virus. We constructed chimeric vpu gene in which the transmembrane domain of Vpu was replaced with that of the M2 protein of influenza. This chimeric vpu gene was substituted for the vpu gene in the genome of a pathogenic simian human immunodeficiency virus, SHIVKU-1bMC33. The resulting virus, SHIVM2, synthesized a Vpu protein that had a slightly different Mr compared to the parental SHIVKU-1bMC33, reflecting the different sizes of the two Vpu proteins. The SHIVM2 was shown to replicate with slightly reduced kinetics when compared to the parental SHIVKU-1bMC33 but electron microscopy revealed that the site of maturation was similar to the parental virus SHIVKU1bMC33. We show that the replication and spread of SHIVM2 could be blocked with the antiviral drug rimantadine, which is known to target the M2 ion channel. Our results indicate a dose dependent inhibition of SHIVM2 with 100 microM rimantadine resulting in a >95% decrease in p27 released into the culture medium. Rimantadine did not affect the replication of the parental SHIVKU-1bMC33. Examination of SHIVM2-infected cells treated with 50 microM rimantadine revealed numerous viral particles associated with the cell plasma membrane and within intracytoplasmic vesicles, which is similar to HIV-1 mutants lacking a functional vpu. To determine if SHIVM2 was as pathogenic as the parental SHIVKU-1bMC33 virus, two pig-tailed macaques were inoculated and followed for up to 8 months. Both pig-tailed macaques developed severe CD4+ T cell loss within 1 month of inoculation, high viral loads, and histological lesions consistent with lymphoid depletion similar to the parental SHIVKU-1bMC33. Taken together, these results indicate for the first time that the TM domain of the Vpu protein can be functionally substituted with the TM of M2 of influenza A virus, and shows that compounds that target the TM domain of Vpu protein of HIV-1 could serve as novel anti-HIV-1 drugs.
Subject(s)
Macaca nemestrina/virology , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/pathogenicity , Viral Matrix Proteins/antagonists & inhibitors , Viral Matrix Proteins/chemistry , Viral Regulatory and Accessory Proteins/chemistry , Viral Regulatory and Accessory Proteins/metabolism , Amino Acid Sequence , Animals , CD4 Antigens/metabolism , Cell Line , Gene Expression Regulation, Viral , Human Immunodeficiency Virus Proteins , Lymphocytes/ultrastructure , Lymphocytes/virology , Molecular Sequence Data , Protein Engineering , Protein Structure, Tertiary , Protein Transport , RNA, Viral/blood , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Simian Immunodeficiency Virus/genetics , Viral Load , Viral Matrix Proteins/genetics , Viral Matrix Proteins/metabolism , Viral Regulatory and Accessory Proteins/geneticsABSTRACT
Previous studies have shown that the transmembrane (TM) domain of the subtype B Vpu enhances virion release from cells and some studies have shown that this domain may form an oligomeric structure with properties of an ion channel. To date, no studies have been performed to assess the role of this domain in virus pathogenesis in a macaque model of disease. Using a pathogenic molecular clone of simian human immunodeficiency virus (SHIVKU-1bMC33), we have generated a novel virus in which the transmembrane domain of the Vpu protein was scrambled but maintained hydrophobic in nature (SHIVTM), which presumably would disrupt any ion channel TM properties of this protein. Vectors expressing the Vpu as a fusion protein with the enhanced green fluorescent protein (VpuTMEGFP) indicate that it was transported to the same intracellular compartment as the unmodified Vpu protein but did not down-regulate cell surface expression of CD4. To assess the pathogenicity of SHIVTM, three pig-tailed macaques were inoculated with the SHIVTM and monitored for 6-8 months for CD4+ T cell levels, viral loads and the stability of the sequence of the vpu gene. Our results indicated that unlike the parental SHIVKU-1bMC33, inoculation of macaques with SHIVTM did not cause a severe CD4+ T cell loss over the course of their infections. Sequence analysis of the vpu gene analyzed from sequential PBMC samples derived from macaques revealed that the scrambled TM was stable during the course of infection. At necropsy, examination of tissues revealed low viral loads and none of the pathology commonly observed in lymphoid and non-lymphoid tissues following inoculation with the pathogenic parental SHIVKU-1bMC33 virus. Thus, these results show for the first time that the TM domain of Vpu contributes to the pathogenicity of SHIVKU-1bMC33 in pig-tailed macaques.
Subject(s)
Acquired Immunodeficiency Syndrome/virology , HIV-1/genetics , Reassortant Viruses/physiology , Simian Immunodeficiency Virus/pathogenicity , Viral Regulatory and Accessory Proteins/physiology , Acquired Immunodeficiency Syndrome/immunology , Animals , CD4 Lymphocyte Count , CD4-Positive T-Lymphocytes/metabolism , Cell Line , Cell Membrane/metabolism , Down-Regulation , Human Immunodeficiency Virus Proteins , Humans , Lymph Nodes/virology , Macaca nemestrina , Protein Structure, Tertiary/physiology , Reassortant Viruses/pathogenicity , Simian Immunodeficiency Virus/genetics , Virulence , Virus ReplicationABSTRACT
The structure of the Vpu protein of human immunodeficiency virus type 1 (HIV-1) is composed of a short Nterminal domain (NTD), a transmembrane domain (TM), and a cytoplasmic domain (CD). Previous studies have shown that the Vpu protein from subtype B HIV-1 is transported predominantly to the rough endoplasmic reticulum (RER)/Golgi complex compartments of the cell and is not incorporated into virions. Using a previously described VpuEGFP reporter system in which the Vpu protein was fused to the gene for enhanced green fluorescent protein (EGFP), we showed that the subtype B Vpu fusion protein was localized to the RER/Golgi region of the cell, similar to the native protein. In the present study, we show that fusion of the subtype C Vpu to EGFP results in a fusion protein that is transported to the cell surface. Using this reporter system, chimeric Vpu proteins in which the CD of the subtype B and C proteins were exchanged showed that the CD was sufficient for targeting the subtype B protein to the Golgi complex of the cell. Following identification of the cytoplasmic domain as being responsible for intracellular targeting, we then generated a series of mutants in which 13, 23, 31, 38, 51, and 56 amino acids were deleted from the cytoplasmic domain of subtype B Vpu. These deletion mutants were analyzed by SDS-PAGE for size, for membrane localization, and intracellular localization by confocal fluorescence microscopy. Our results indicate that the mutant with the carboxyl-terminal 13 amino acids deleted was still localized to the Golgi complex but mutants with 23, 31, 38, 51, and 56 amino acids from the carboxyl-terminus of the subtype B Vpu were transported to the cell surface. These results suggest that a signal for the retention of the subtype B Vpu within the Golgi complex resides in the second alpha-helical domain.
Subject(s)
Gene Expression Regulation, Viral , Golgi Apparatus/metabolism , HIV-1/classification , Viral Regulatory and Accessory Proteins/chemistry , Viral Regulatory and Accessory Proteins/genetics , Amino Acid Sequence , Cell Line , Gene Deletion , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , HIV-1/genetics , HIV-1/metabolism , HeLa Cells , Human Immunodeficiency Virus Proteins , Humans , Molecular Sequence Data , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Transfection , Viral Regulatory and Accessory Proteins/metabolismABSTRACT
The Vpu protein is the smallest of the proteins encoded by human immunodeficiency virus type 1 (HIV-1). This transmembrane protein interacts with the CD4 molecule in the rough endoplasmic reticulum (RER), resulting in its degradation via the proteasome pathway. Vpu also has been shown to enhance virion release from infected cells. While much has been learned about the function of Vpu in cell culture systems, its exact role in HIV-1 pathogenesis is still unknown. This has been primarily due to the lack of a suitable primate model system since vpu is found only in HIV-1 and simian immunodeficiency viruses isolated from chimpanzees (SIVcpz), and three species of old world monkeys within the genus Cercopithecus. Several laboratories have developed pathogenic molecular clones of simian-human immunodeficiency virus (SHIV) in which the tat, rev, vpu and env genes of HIV-1 are expressed in the genetic background of SIV. The availability of such clones has allowed investigators to assess the role of Vpu in pathogenesis using a relevant animal model. This review will focus on the current understanding of the structure-function relationships of Vpu protein and recent advances using the SHIV model to assess the role of Vpu in HIV-1 pathogenesis.
Subject(s)
Genes, vpu/physiology , HIV Infections/virology , HIV-1/pathogenicity , Viral Regulatory and Accessory Proteins/physiology , Amino Acid Sequence , Animals , Base Sequence , CD4 Antigens/immunology , Cell Membrane/virology , Disease Models, Animal , HIV-1/physiology , Human Immunodeficiency Virus Proteins , Humans , Macaca , Molecular Sequence Data , Reassortant Viruses , Sequence Alignment , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/genetics , Viral Regulatory and Accessory Proteins/genetics , Viral Regulatory and Accessory Proteins/immunology , Virulence , Virus ReplicationABSTRACT
The presence of the prion agent in skeletal muscle is thought to be due to the infection of nerve fibers located within the muscle. We report here that the pathological isoform of the prion protein, PrP(Sc), accumulates within skeletal muscle cells, in addition to axons, in the tongue of hamsters following intralingual and intracerebral inoculation of the HY strain of the transmissible mink encephalopathy agent. Localization of PrP(Sc) to the neuromuscular junction suggests that this synapse is a site for prion agent spread between motor axon terminals and muscle cells. Following intracerebral inoculation, the majority of PrP(Sc) in the tongue was found in the lamina propria, where it was associated with sensory nerve fibers in the core of the lingual papillae. PrP(Sc) staining was also identified in the stratified squamous epithelium of the lingual mucosa. These findings indicate that prion infection of skeletal muscle cells and the epithelial layer in the tongue can be established following the spread of the prion agent from nerve terminals and/or axons that innervate the tongue. Our data suggest that ingestion of meat products containing prion-infected tongue could result in human exposure to the prion agent, while sloughing of prion-infected epithelial cells at the mucosal surface of the tongue could be a mechanism for prion agent shedding and subsequent prion transmission in animals.
Subject(s)
Muscle, Skeletal/metabolism , PrPSc Proteins/pathogenicity , Prion Diseases/metabolism , Tongue/metabolism , Animals , Cricetinae , Mesocricetus , Microscopy, Confocal , Mink , Muscle, Skeletal/cytology , Neuromuscular Junction/metabolism , Telencephalon/metabolism , Tongue/ultrastructure , Tongue Diseases/metabolismABSTRACT
Previous studies have shown that the gene coding for the Vpu protein of the human immunodeficiency virus type 1 (HIV-1) is 5' to the env gene, is in a different reading frame, and overlaps the env by 90 nucleotides. In this study, we examined the processing of the Env protein as well as the maturation and infectivity of a virus (SHIV(Vpenv)) in which a single nucleotide was removed at the vpu-env junction, fusing the first 162 bases of vpu to the env ORF. Pulse-chase analysis revealed that SHIV(Vpenv)-infected cells gave rise to two precursor glycoprotein species (gp160 and gp175). Immune precipitation results also revealed that an anti-Vpu serum could immune precipitate the gp175 precursor, suggesting that the amino-terminal Vpu sequence was fused to the Env protein. Growth curves revealed that the SHIV(Vpenv)-inoculated cultures released approximately three times more p27 into the culture medium than parental SHIV(KU-1bMC33). Electron microscopy revealed that while both viruses matured at the cell plasma membrane, significantly higher quantities of virus particles were cell associated on SHIV(Vpenv)-infected cells compared to cultures inoculated with parental SHIV(KU-1bMC33). Furthermore, virus was observed maturing into intracellular vesicles of SHIV(Vpenv)-infected cells. To assess the pathogenicity of SHIV(Vpenv), three pig-tailed macaques were inoculated with the SHIV(Vpenv) and monitored for 6 months for CD4(+) T cell levels, viral loads, and the stability of the deletion at the vpu-env junction. Our results indicated that SHIV(Vpenv) caused a severe CD4(+) T cell loss in all three macaques within weeks of inoculation. Sequence analysis of the vpu gene analyzed from sequential PBMC samples derived from macaques revealed that this mutation was stable during the period of rapid CD4(+) T cell loss. Sequence analysis showed that with increasing time of infection, the one base pair deletion was repaired in all three macaques inoculated with SHIV(Vpenv) with the reversion occurring at 10 weeks in macaque CT1G and at 12 weeks in macaque CP3R and CT1R. These results indicate that fusion of the first 54 amino acids of Vpu to Env results in intracellular maturation of virus, and accumulation of virus within intracellular vesicles as well as on the cell plasma membrane. Our results indicate that while fusion of the vpu gene to env results in a virus that is still pathogenic for pig-tailed macaques, there is a selective pressure to maintain the vpu and env genes in separate reading frames.
Subject(s)
Gene Products, env/metabolism , HIV-1/pathogenicity , Protein Precursors/metabolism , Simian Immunodeficiency Virus/pathogenicity , Viral Regulatory and Accessory Proteins/metabolism , Virion/metabolism , Amino Acid Sequence , Animals , Base Sequence , Cell Line , HIV Envelope Protein gp160/metabolism , HIV Infections/virology , HIV-1/physiology , Human Immunodeficiency Virus Proteins , Humans , Lymphocytes/virology , Macaca/virology , Molecular Sequence Data , Sequence Analysis, DNA , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/physiology , Viral Regulatory and Accessory Proteins/chemistry , Viral Regulatory and Accessory Proteins/geneticsABSTRACT
The molecular basis of prion strain diversity is proposed to be encoded by distinct conformations of the abnormal scrapie isoform of the prion protein (PrP(Sc)). PrP(Sc) formation for the hyper (HY) and drowsy (DY) strains of the transmissible mink encephalopathy (TME) agent was investigated using the cell-free PrP conversion reaction to determine the role of distinct PrP(Sc) conformations in the rate of in vitro conversion of cellular PrP into protease-resistant PrP. PrP conversion increased at an exponential rate for both TME strains until peak levels were reached at 72-96 h of reaction time. The amount and rate of PrP conversion for HY TME was greater than those for DY TME between 48 h and the peak level of PrP conversion. Between 96 and 120 h, there was a negative rate of PrP conversion; and between 120 and 168 h, the net rate of HY and DY PrP conversion approached zero. These findings suggest that PrP conversion can occur in three distinct stages: an elongation phase, a depolymerization phase, and a steady-state phase. Strain-specific properties between the TME strains were identified only during the elongation phase. The steady-state phase could be disrupted by the addition of PrP(Sc) to, or by sonication of, the cell-free PrP conversion reaction. These treatments resulted in an increase in the amount of PrP conversion that was equal to or greater than that found during the peak level of PrP conversion for both TME strains, indicating that the steady-state phase was in dynamic equilibrium. In a related study, the rate of accumulation of HY and DY PrP(Sc) in hamster brain exhibited a strain-specific pattern that had similarities to the strain-specific PrP conversion reaction during the elongation phase. These results suggest that strain-specific conformations of PrP(Sc) have the ability to influence the rate of additional PrP(Sc) formation from cellular PrP both in vitro and in vivo.