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Two minimally invasive assays for detecting prions that are diagnostic of Creutzfeldt-Jakob disease in living patients have shown promise in preliminary studies reported by separate research groups Aug. 6 in the New England Journal of Medicine.
One assay tests epithelial samples obtained from nasal brushings and the other tests urine samples; both can be used in patients suspected of having the sporadic, inherited, or acquired forms of Creutzfeldt-Jakob disease (CJD), such as variant CJD and iatrogenic CJD. Both assays achieved sensitivities and specificities of 93%-100% in very small patient populations in these exploratory studies, which is better than the diagnostic accuracy of cerebrospinal fluid (CSF) testing.
If these findings are replicated in larger studies, both assays have the potential for establishing a definitive diagnosis of CJD in clinical settings. The test that uses nasal brushings may do so earlier in the course of the disease than has been possible previously, at least allowing the possibility of intervention for this invariably fatal neurodegenerative disorder.
In addition, the incidental finding that simple brushing of the olfactory mucosa yields an even higher quantity of prion "seeds" than are found in patients’ CSF suggests that infectivity may be present in the nasal cavity, which has important biosafety implications, the researchers noted.
In the first report, investigators applied real-time quaking-induced conversion (RT-QuIC) technology to olfactory epithelium samples from 31 patients who had rapidly progressive dementia and were referred for evaluation of possible or probable CJD from clinicians across Italy. These patients also underwent CSF sampling at the same time. A total of 12 patients with other neurodegenerative disorders (chiefly Alzheimer’s disease or Parkinson’s disease) and 31 patients at an ear, nose, and throat clinic who had no neurologic disorders served as controls, said Christina D. Orrú, Ph.D., of the Laboratory of Persistent Viral Diseases at the National Institute of Allergy and Infectious Diseases’ Rocky Mountain Laboratories in Hamilton, Mont., and her associates.
Obtaining the nasal brushings was described as a gentle procedure in which unsedated patients were first given a local vasoconstrictor applied with a nasal tampon, and then had a fiberoptic rhinoscope with a disposable sheath inserted into the nasal cavity to locate the olfactory mucosal lining of the nasal vault. A sterile, disposable brush was inserted alongside the rhinoscope, gently rolled on the mucosal surface, withdrawn, and immersed in saline solution in a centrifuge tube for further preparation.
The assays using this material yielded positive results for 15 of the 15 patients who had definite sporadic CJD, 13 of the 14 who had probable sporadic CJD, and 2 of the 2 patients who had inherited CJD. In contrast, all 43 control subjects had negative results. This represents a sensitivity of 97% (95% confidence interval [CI], 82-100) and a specificity of 100% (95% CI, 90-100) in this study population. In comparison, testing of CSF samples from the same patients only achieved a 77% sensitivity (95% CI, 57-89), Dr. Orrú and her associates said (N. Engl. J. Med. 2014 Aug. 6 [doi:10.1056/NEJMoa1315200]).
In addition, the "substantial" prion seeding found in the olfactory mucosa – greater than that in the CSF – raises the possibility that CJD prions could contaminate patients’ nasal discharges. "Nasal and aerosol-borne transmission of prion diseases have been documented in animal models, but there is no epidemiologic evidence for aerosol-borne transmission of sporadic CJD" to date, the investigators wrote.
It also is possible that medical instruments that come into contact with the nasal mucosa may become contaminated with prions, "which poses the question of whether iatrogenic transmission is possible. Therefore, further study of possible biohazards ... is warranted," they added.
In the second report, Fabio Moda, Ph.D., of the Mitchell Center for Research in Alzheimer’s Disease and Related Brain Disorders at the University of Texas, Houston, and his associates assayed urine samples using an extensive amplification technology for the presence of minute quantities of the misfolded prion protein in 68 patients with sporadic CJD, 14 with variant CJD, and 156 controls. The control group included 4 patients with genetic prion diseases, 50 with other neurodegenerative disorders (Alzheimer’s disease, Parkinson’s disease, frontotemporal dementia, motor neuron disease, and progressive supranuclear palsy), 50 patients with nondegenerative neurologic disorders (chiefly cerebrovascular disease, multiple sclerosis, epilepsy, brain tumors, autoimmune encephalitis, and meningitis), and 52 healthy adults.
This assay achieved a sensitivity of 93% (95% CI, 66.1-99.8) and a specificity of 100% (95% CI, 98.4-100.0) in distinguishing CJD from other brain disorders and from brain health in this patient population, they said (N. Engl. J. Med. 2014 Aug. 6 [doi:10.1056/NEJMoa1404401]).
The quantities of the prion protein excreted in the urine were extremely small, so the potential for infectivity was not addressed in this study.
Dr. Orrú’s study was funded by the National Institute of Allergy and Infectious Diseases; Fondazione Cariverona; the Italian Ministry of Health; the Creutzfeldt-Jakob Disease Foundation; Programma Master and Back-Percorsi di rientro; and by donations in memory of Jeffrey Smith from Mary Hilderman Smith, Zoe Smith Jaye, and Jenny Smith Unruh. Dr. Moda’s study was funded by the National Institutes of Health, PrioNet Canada, Merck Serono, the Italian Ministry of Health, Associazione Italiana Encefalopatie da Prioni, Ministero dell’Universita e della Ricerca, the Charles S. Britton Fund, the U.K. Department of Health, and the Scottish government.
These findings are encouraging because clinicians and researchers have long sought a sensitive and minimally invasive diagnostic tool specifically targeted to the protein that causes all forms of CJD, said Dr. Colin L. Masters.
It will, however, be important for additional studies to determine more precise estimates of the tests’ specificities – necessitated by the wide confidence intervals reported for the tests’ specificities – because the techniques used can give rise to "breakthrough" false-positive results. "Creutzfeldt-Jakob disease is extremely uncommon, and a test without near-perfect specificity may also result in many false positive results if it is applied to patients with a low probability of having the disease. In these circumstances, it is important to highlight the preliminary nature of these studies," Dr. Masters wrote.
Moreover, the finding that abnormal prion protein "seeds" are found in the olfactory mucosa "at concentrations equivalent to those in diseased brain, and several logs greater than those in cerebrospinal fluid," has implications for infection control. "Some experts have [already] recommended appropriate decontamination of surgical instruments that come into contact with the olfactory epithelium of patients at high risk for Creutzfeldt-Jakob disease," he said.
Dr. Master is with the Florey Institute of Neuroscience and Mental Health at the University of Melbourne. These remarks were taken from his editorial accompanying the two reports on CJD assays (N. Engl. J. Med. 2014 August 6 [doi:10.1056/NEJMe1407419]).
These findings are encouraging because clinicians and researchers have long sought a sensitive and minimally invasive diagnostic tool specifically targeted to the protein that causes all forms of CJD, said Dr. Colin L. Masters.
It will, however, be important for additional studies to determine more precise estimates of the tests’ specificities – necessitated by the wide confidence intervals reported for the tests’ specificities – because the techniques used can give rise to "breakthrough" false-positive results. "Creutzfeldt-Jakob disease is extremely uncommon, and a test without near-perfect specificity may also result in many false positive results if it is applied to patients with a low probability of having the disease. In these circumstances, it is important to highlight the preliminary nature of these studies," Dr. Masters wrote.
Moreover, the finding that abnormal prion protein "seeds" are found in the olfactory mucosa "at concentrations equivalent to those in diseased brain, and several logs greater than those in cerebrospinal fluid," has implications for infection control. "Some experts have [already] recommended appropriate decontamination of surgical instruments that come into contact with the olfactory epithelium of patients at high risk for Creutzfeldt-Jakob disease," he said.
Dr. Master is with the Florey Institute of Neuroscience and Mental Health at the University of Melbourne. These remarks were taken from his editorial accompanying the two reports on CJD assays (N. Engl. J. Med. 2014 August 6 [doi:10.1056/NEJMe1407419]).
These findings are encouraging because clinicians and researchers have long sought a sensitive and minimally invasive diagnostic tool specifically targeted to the protein that causes all forms of CJD, said Dr. Colin L. Masters.
It will, however, be important for additional studies to determine more precise estimates of the tests’ specificities – necessitated by the wide confidence intervals reported for the tests’ specificities – because the techniques used can give rise to "breakthrough" false-positive results. "Creutzfeldt-Jakob disease is extremely uncommon, and a test without near-perfect specificity may also result in many false positive results if it is applied to patients with a low probability of having the disease. In these circumstances, it is important to highlight the preliminary nature of these studies," Dr. Masters wrote.
Moreover, the finding that abnormal prion protein "seeds" are found in the olfactory mucosa "at concentrations equivalent to those in diseased brain, and several logs greater than those in cerebrospinal fluid," has implications for infection control. "Some experts have [already] recommended appropriate decontamination of surgical instruments that come into contact with the olfactory epithelium of patients at high risk for Creutzfeldt-Jakob disease," he said.
Dr. Master is with the Florey Institute of Neuroscience and Mental Health at the University of Melbourne. These remarks were taken from his editorial accompanying the two reports on CJD assays (N. Engl. J. Med. 2014 August 6 [doi:10.1056/NEJMe1407419]).
Two minimally invasive assays for detecting prions that are diagnostic of Creutzfeldt-Jakob disease in living patients have shown promise in preliminary studies reported by separate research groups Aug. 6 in the New England Journal of Medicine.
One assay tests epithelial samples obtained from nasal brushings and the other tests urine samples; both can be used in patients suspected of having the sporadic, inherited, or acquired forms of Creutzfeldt-Jakob disease (CJD), such as variant CJD and iatrogenic CJD. Both assays achieved sensitivities and specificities of 93%-100% in very small patient populations in these exploratory studies, which is better than the diagnostic accuracy of cerebrospinal fluid (CSF) testing.
If these findings are replicated in larger studies, both assays have the potential for establishing a definitive diagnosis of CJD in clinical settings. The test that uses nasal brushings may do so earlier in the course of the disease than has been possible previously, at least allowing the possibility of intervention for this invariably fatal neurodegenerative disorder.
In addition, the incidental finding that simple brushing of the olfactory mucosa yields an even higher quantity of prion "seeds" than are found in patients’ CSF suggests that infectivity may be present in the nasal cavity, which has important biosafety implications, the researchers noted.
In the first report, investigators applied real-time quaking-induced conversion (RT-QuIC) technology to olfactory epithelium samples from 31 patients who had rapidly progressive dementia and were referred for evaluation of possible or probable CJD from clinicians across Italy. These patients also underwent CSF sampling at the same time. A total of 12 patients with other neurodegenerative disorders (chiefly Alzheimer’s disease or Parkinson’s disease) and 31 patients at an ear, nose, and throat clinic who had no neurologic disorders served as controls, said Christina D. Orrú, Ph.D., of the Laboratory of Persistent Viral Diseases at the National Institute of Allergy and Infectious Diseases’ Rocky Mountain Laboratories in Hamilton, Mont., and her associates.
Obtaining the nasal brushings was described as a gentle procedure in which unsedated patients were first given a local vasoconstrictor applied with a nasal tampon, and then had a fiberoptic rhinoscope with a disposable sheath inserted into the nasal cavity to locate the olfactory mucosal lining of the nasal vault. A sterile, disposable brush was inserted alongside the rhinoscope, gently rolled on the mucosal surface, withdrawn, and immersed in saline solution in a centrifuge tube for further preparation.
The assays using this material yielded positive results for 15 of the 15 patients who had definite sporadic CJD, 13 of the 14 who had probable sporadic CJD, and 2 of the 2 patients who had inherited CJD. In contrast, all 43 control subjects had negative results. This represents a sensitivity of 97% (95% confidence interval [CI], 82-100) and a specificity of 100% (95% CI, 90-100) in this study population. In comparison, testing of CSF samples from the same patients only achieved a 77% sensitivity (95% CI, 57-89), Dr. Orrú and her associates said (N. Engl. J. Med. 2014 Aug. 6 [doi:10.1056/NEJMoa1315200]).
In addition, the "substantial" prion seeding found in the olfactory mucosa – greater than that in the CSF – raises the possibility that CJD prions could contaminate patients’ nasal discharges. "Nasal and aerosol-borne transmission of prion diseases have been documented in animal models, but there is no epidemiologic evidence for aerosol-borne transmission of sporadic CJD" to date, the investigators wrote.
It also is possible that medical instruments that come into contact with the nasal mucosa may become contaminated with prions, "which poses the question of whether iatrogenic transmission is possible. Therefore, further study of possible biohazards ... is warranted," they added.
In the second report, Fabio Moda, Ph.D., of the Mitchell Center for Research in Alzheimer’s Disease and Related Brain Disorders at the University of Texas, Houston, and his associates assayed urine samples using an extensive amplification technology for the presence of minute quantities of the misfolded prion protein in 68 patients with sporadic CJD, 14 with variant CJD, and 156 controls. The control group included 4 patients with genetic prion diseases, 50 with other neurodegenerative disorders (Alzheimer’s disease, Parkinson’s disease, frontotemporal dementia, motor neuron disease, and progressive supranuclear palsy), 50 patients with nondegenerative neurologic disorders (chiefly cerebrovascular disease, multiple sclerosis, epilepsy, brain tumors, autoimmune encephalitis, and meningitis), and 52 healthy adults.
This assay achieved a sensitivity of 93% (95% CI, 66.1-99.8) and a specificity of 100% (95% CI, 98.4-100.0) in distinguishing CJD from other brain disorders and from brain health in this patient population, they said (N. Engl. J. Med. 2014 Aug. 6 [doi:10.1056/NEJMoa1404401]).
The quantities of the prion protein excreted in the urine were extremely small, so the potential for infectivity was not addressed in this study.
Dr. Orrú’s study was funded by the National Institute of Allergy and Infectious Diseases; Fondazione Cariverona; the Italian Ministry of Health; the Creutzfeldt-Jakob Disease Foundation; Programma Master and Back-Percorsi di rientro; and by donations in memory of Jeffrey Smith from Mary Hilderman Smith, Zoe Smith Jaye, and Jenny Smith Unruh. Dr. Moda’s study was funded by the National Institutes of Health, PrioNet Canada, Merck Serono, the Italian Ministry of Health, Associazione Italiana Encefalopatie da Prioni, Ministero dell’Universita e della Ricerca, the Charles S. Britton Fund, the U.K. Department of Health, and the Scottish government.
Two minimally invasive assays for detecting prions that are diagnostic of Creutzfeldt-Jakob disease in living patients have shown promise in preliminary studies reported by separate research groups Aug. 6 in the New England Journal of Medicine.
One assay tests epithelial samples obtained from nasal brushings and the other tests urine samples; both can be used in patients suspected of having the sporadic, inherited, or acquired forms of Creutzfeldt-Jakob disease (CJD), such as variant CJD and iatrogenic CJD. Both assays achieved sensitivities and specificities of 93%-100% in very small patient populations in these exploratory studies, which is better than the diagnostic accuracy of cerebrospinal fluid (CSF) testing.
If these findings are replicated in larger studies, both assays have the potential for establishing a definitive diagnosis of CJD in clinical settings. The test that uses nasal brushings may do so earlier in the course of the disease than has been possible previously, at least allowing the possibility of intervention for this invariably fatal neurodegenerative disorder.
In addition, the incidental finding that simple brushing of the olfactory mucosa yields an even higher quantity of prion "seeds" than are found in patients’ CSF suggests that infectivity may be present in the nasal cavity, which has important biosafety implications, the researchers noted.
In the first report, investigators applied real-time quaking-induced conversion (RT-QuIC) technology to olfactory epithelium samples from 31 patients who had rapidly progressive dementia and were referred for evaluation of possible or probable CJD from clinicians across Italy. These patients also underwent CSF sampling at the same time. A total of 12 patients with other neurodegenerative disorders (chiefly Alzheimer’s disease or Parkinson’s disease) and 31 patients at an ear, nose, and throat clinic who had no neurologic disorders served as controls, said Christina D. Orrú, Ph.D., of the Laboratory of Persistent Viral Diseases at the National Institute of Allergy and Infectious Diseases’ Rocky Mountain Laboratories in Hamilton, Mont., and her associates.
Obtaining the nasal brushings was described as a gentle procedure in which unsedated patients were first given a local vasoconstrictor applied with a nasal tampon, and then had a fiberoptic rhinoscope with a disposable sheath inserted into the nasal cavity to locate the olfactory mucosal lining of the nasal vault. A sterile, disposable brush was inserted alongside the rhinoscope, gently rolled on the mucosal surface, withdrawn, and immersed in saline solution in a centrifuge tube for further preparation.
The assays using this material yielded positive results for 15 of the 15 patients who had definite sporadic CJD, 13 of the 14 who had probable sporadic CJD, and 2 of the 2 patients who had inherited CJD. In contrast, all 43 control subjects had negative results. This represents a sensitivity of 97% (95% confidence interval [CI], 82-100) and a specificity of 100% (95% CI, 90-100) in this study population. In comparison, testing of CSF samples from the same patients only achieved a 77% sensitivity (95% CI, 57-89), Dr. Orrú and her associates said (N. Engl. J. Med. 2014 Aug. 6 [doi:10.1056/NEJMoa1315200]).
In addition, the "substantial" prion seeding found in the olfactory mucosa – greater than that in the CSF – raises the possibility that CJD prions could contaminate patients’ nasal discharges. "Nasal and aerosol-borne transmission of prion diseases have been documented in animal models, but there is no epidemiologic evidence for aerosol-borne transmission of sporadic CJD" to date, the investigators wrote.
It also is possible that medical instruments that come into contact with the nasal mucosa may become contaminated with prions, "which poses the question of whether iatrogenic transmission is possible. Therefore, further study of possible biohazards ... is warranted," they added.
In the second report, Fabio Moda, Ph.D., of the Mitchell Center for Research in Alzheimer’s Disease and Related Brain Disorders at the University of Texas, Houston, and his associates assayed urine samples using an extensive amplification technology for the presence of minute quantities of the misfolded prion protein in 68 patients with sporadic CJD, 14 with variant CJD, and 156 controls. The control group included 4 patients with genetic prion diseases, 50 with other neurodegenerative disorders (Alzheimer’s disease, Parkinson’s disease, frontotemporal dementia, motor neuron disease, and progressive supranuclear palsy), 50 patients with nondegenerative neurologic disorders (chiefly cerebrovascular disease, multiple sclerosis, epilepsy, brain tumors, autoimmune encephalitis, and meningitis), and 52 healthy adults.
This assay achieved a sensitivity of 93% (95% CI, 66.1-99.8) and a specificity of 100% (95% CI, 98.4-100.0) in distinguishing CJD from other brain disorders and from brain health in this patient population, they said (N. Engl. J. Med. 2014 Aug. 6 [doi:10.1056/NEJMoa1404401]).
The quantities of the prion protein excreted in the urine were extremely small, so the potential for infectivity was not addressed in this study.
Dr. Orrú’s study was funded by the National Institute of Allergy and Infectious Diseases; Fondazione Cariverona; the Italian Ministry of Health; the Creutzfeldt-Jakob Disease Foundation; Programma Master and Back-Percorsi di rientro; and by donations in memory of Jeffrey Smith from Mary Hilderman Smith, Zoe Smith Jaye, and Jenny Smith Unruh. Dr. Moda’s study was funded by the National Institutes of Health, PrioNet Canada, Merck Serono, the Italian Ministry of Health, Associazione Italiana Encefalopatie da Prioni, Ministero dell’Universita e della Ricerca, the Charles S. Britton Fund, the U.K. Department of Health, and the Scottish government.
FROM THE NEW ENGLAND JOURNAL OF MEDICINE
Key clinical point: Two minimally invasive approaches to detecting misfolded prion proteins have high sensitivities and specificities for detecting forms of Creutzfeldt-Jakob disease.
Major finding: The assay of nasal brushings achieved a sensitivity of 97% and a specificity of 100% in identifying CJD in living patients, while the urine assay achieved a sensitivity of 93% and a specificity of 100%.
Data source: A case-control study of the diagnostic accuracy of an assay of nasal brushings, involving 31 patients with suspected CJD and 43 control subjects (Dr. Orrú), and a case-control study of the diagnostic accuracy of an assay of urine samples, involving 82 patients with various forms of CJD and 156 controls (Dr. Moda).
Disclosures: Dr. Orrú’s study was funded by foundations, private donations, and governmental institutes, including the National Institute of Allergy and Infectious Diseases. Dr. Moda’s study was funded by Italian, British, and Scottish government entities, private funds, Merck Serono, the National Institutes of Health, and PrioNet Canada.
