RT-QuIC detection of pathological prion protein in subclinical goats following experimental oral transmission of L-type BSE
Alessandra Favole1* , Maria Mazza1 , Antonio D'Angelo2 , Guerino Lombardi3 , Claudia Palmitessa1 , Luana Dell'Atti1 , Giulia Cagnotti2 , Elena Berrone1 , Marina Gallo1 , Tiziana Avanzato1 , Erika Messana1 , Loretta Masoero1 , Pier Luigi Acutis1 , Daniela Meloni1 , Franco Cardone4 , Maria Caramelli1 , Cristina Casalone1 and Cristiano Corona1*
Abstract
Objective: The spread of bovine spongiform encephalopathy (BSE) agent to small ruminants is still a major issue in the surveillance of transmissible spongiform encephalopathies (TSEs). L-type bovine spongiform encephalopathy (L-BSE) is an atypical form of BSE with an unknown zoonotic potential that is transmissible to cattle and small ruminants. Our current knowledge of bovine atypical prion strains in sheep and goat relies only on experimental transmission studies by intracranial inoculation. To assess oral susceptibility of goats to L-BSE, we orally inoculated five goats with cattle L-BSE brain homogenates and investigated pathogenic prion protein (PrPsc) distribution by an ultrasensitive in vitro conversion assay known as Real-Time Quaking Induced Conversion (RT-QuIC).
Results: Despite a prolonged observation period of 80 months, all these animals and the uninfected controls did not develop clinical signs referable to TSEs and tested negative by standard diagnostics. Otherwise, RT-QuIC analysis showed seeding activity in five out of five examined brain samples. PrPsc accumulation was also detected in spinal cord and lymphoreticular system. These results indicate that caprine species are susceptible to L-BSE by oral transmission and that ultrasensitive prion tests deserve consideration to improve the potential of current surveillance systems against otherwise undetectable forms of animal prion infections.
snip...
Discussion and conclusions
Data here presented indicate that caprine species are susceptible to L-BSE after oral administration and are able to produce very low levels of prions in both lymphatic and central nervous tissues as demonstrated by optimized, high-sensitive, RT-QuIC assay.
At variance with goats intracerebrally infected with L-BSE [4], in this study, no animal developed clinical signs of disease despite prolonged periods of observation, suggesting a comparatively low efficiency of the oral route versus the intracerebral one in L-BSE, a feature that further distinguish this strain from classical BSE [14, 15].
Interestingly, all goats tested negative by standard diagnostics for PrPsc performed on brainstem. This finding, associated with the low amount of PrPsc detected in different brain areas, suggests a partial strain-specific transmission barrier. Indeed, inoculation of a prion into a new host species can produce prolonged incubation periods and/or subclinical infection [16, 17]. In addition, the lack of clinical signs suggests that naturally L-BSE-infected goats may be asymptomatic similarly to what proposed by Okada et al. for oral L-BSE in cattle [17].
In line with previous results [18], RT-QuIC detected lower levels of prions than traditional diagnostic tools. Rapid and confirmatory tests failed to identify any PrPsc in the subclinical animals, while RT-QuIC allowed us to detect misfolded prion protein in multiple brain regions, spinal cord and lymphoreticular system. Studies have established that the rate of fluorescence increase in RTQuIC, while not measuring infectivity, is directly related to the concentration of prions in the sample seeding the reaction [19, 20]. Prolonged lag phases of RT-QuIC reactions indicate relatively low amounts of PrPsc in the examined tissues and may reassure about the possibility of goat to play as silent L-BSE spreaders in natural conditions. However, we believe that prudence must be always adopted when dealing with the risk of prion spread in field conditions as also suggested by recent data by Denkers and colleagues, who showed that the oral route of infection for chronic wasting disease in deer, may be much more efficient than previously thought [21]. Furthermore, although the mere presence of PrPsc is not indicative of a possible infectivity of the tissue, the finding of positivity in the lymphoreticular tissue must alert to the potential distribution of PrPsc in peripheral body regions which may increase the risks for humans. Bioassay of infectivity by inoculation of susceptible animals with brains of these goats may help to clarify this issue.
Based on the results achieved with this prion form and also other animal strains, it would be useful to consider the possibility to enlarge current diagnostic criteria to include, in defined conditions (e.g. very limited amounts of source tissue, or preclinical testing), the application of ultrasensitive diagnostic methods. This will not only improve the sensitivity of our surveillance systems but will also help to protect food chain from accidental spillovers of the agent of L-BSE.
Limitations
Te primary limitation of this work is that infectivity was not demonstrated by bioassay and the infectious titre was not determined. Therefore, we cannot comment the degree of risk for human.
Despite these limitations, this work specifically demonstrates prion-seeding activity in tissues of goats orally exposed to L-BSE and provide RT-QuIC as useful method to enhance surveillance of TSEs.
Keywords: Prion, L-BSE, RT-QuIC, Goat, Oral transmission, PrPsc, Ultrasensitive detection
snip...see full text;
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC8650279&blobtype=pdf
WEDNESDAY, DECEMBER 8, 2021
Importation of Sheep, Goats, and Certain Other Ruminants AGENCY: Animal APHIA, USDA, FINAL RULE [Docket No. APHIS–2009–0095] RIN 0579–AD10
snip...
WTF were they thinking...
Isolation of Prion with BSE Properties from Farmed Goat
***> Our data show that BSE can infect small ruminants under natural conditions and could be misdiagnosed as scrapie
wtf were they thinking...
snip...see full report ;
WEDNESDAY, DECEMBER 8, 2021
Importation of Sheep, Goats, and Certain Other Ruminants AGENCY: Animal APHIA, USDA, FINAL RULE [Docket No. APHIS–2009–0095] RIN 0579–AD10
https://animalhealthreportpriontse.blogspot.com/2021/12/importation-of-sheep-goats-and-certain.html
https://www.usda.gov/topics/animals/bse-surveillance-information-center
https://www.cdc.gov/prions/bse/case-us.html
TUESDAY, SEPTEMBER 07, 2021
Atypical Bovine Spongiform Encephalopathy BSE OIE, FDA 589.2001 FEED REGULATIONS, and Ingestion Therefrom
https://bse-atypical.blogspot.com/2021/09/atypical-bovine-spongiform.html
http://bovineprp.blogspot.com/2020/12/bse-research-project-final-report-2005.html
see full text;
MONDAY, DECEMBER 27, 2021
RT-QuIC detection of pathological prion protein in subclinical goats following experimental oral transmission of L-type BSE
https://bse-atypical.blogspot.com/2021/12/rt-quic-detection-of-pathological-prion.html
terry
Alessandra Favole1* , Maria Mazza1 , Antonio D'Angelo2 , Guerino Lombardi3 , Claudia Palmitessa1 , Luana Dell'Atti1 , Giulia Cagnotti2 , Elena Berrone1 , Marina Gallo1 , Tiziana Avanzato1 , Erika Messana1 , Loretta Masoero1 , Pier Luigi Acutis1 , Daniela Meloni1 , Franco Cardone4 , Maria Caramelli1 , Cristina Casalone1 and Cristiano Corona1*
Abstract
Objective: The spread of bovine spongiform encephalopathy (BSE) agent to small ruminants is still a major issue in the surveillance of transmissible spongiform encephalopathies (TSEs). L-type bovine spongiform encephalopathy (L-BSE) is an atypical form of BSE with an unknown zoonotic potential that is transmissible to cattle and small ruminants. Our current knowledge of bovine atypical prion strains in sheep and goat relies only on experimental transmission studies by intracranial inoculation. To assess oral susceptibility of goats to L-BSE, we orally inoculated five goats with cattle L-BSE brain homogenates and investigated pathogenic prion protein (PrPsc) distribution by an ultrasensitive in vitro conversion assay known as Real-Time Quaking Induced Conversion (RT-QuIC).
Results: Despite a prolonged observation period of 80 months, all these animals and the uninfected controls did not develop clinical signs referable to TSEs and tested negative by standard diagnostics. Otherwise, RT-QuIC analysis showed seeding activity in five out of five examined brain samples. PrPsc accumulation was also detected in spinal cord and lymphoreticular system. These results indicate that caprine species are susceptible to L-BSE by oral transmission and that ultrasensitive prion tests deserve consideration to improve the potential of current surveillance systems against otherwise undetectable forms of animal prion infections.
snip...
Discussion and conclusions
Data here presented indicate that caprine species are susceptible to L-BSE after oral administration and are able to produce very low levels of prions in both lymphatic and central nervous tissues as demonstrated by optimized, high-sensitive, RT-QuIC assay.
At variance with goats intracerebrally infected with L-BSE [4], in this study, no animal developed clinical signs of disease despite prolonged periods of observation, suggesting a comparatively low efficiency of the oral route versus the intracerebral one in L-BSE, a feature that further distinguish this strain from classical BSE [14, 15].
Interestingly, all goats tested negative by standard diagnostics for PrPsc performed on brainstem. This finding, associated with the low amount of PrPsc detected in different brain areas, suggests a partial strain-specific transmission barrier. Indeed, inoculation of a prion into a new host species can produce prolonged incubation periods and/or subclinical infection [16, 17]. In addition, the lack of clinical signs suggests that naturally L-BSE-infected goats may be asymptomatic similarly to what proposed by Okada et al. for oral L-BSE in cattle [17].
In line with previous results [18], RT-QuIC detected lower levels of prions than traditional diagnostic tools. Rapid and confirmatory tests failed to identify any PrPsc in the subclinical animals, while RT-QuIC allowed us to detect misfolded prion protein in multiple brain regions, spinal cord and lymphoreticular system. Studies have established that the rate of fluorescence increase in RTQuIC, while not measuring infectivity, is directly related to the concentration of prions in the sample seeding the reaction [19, 20]. Prolonged lag phases of RT-QuIC reactions indicate relatively low amounts of PrPsc in the examined tissues and may reassure about the possibility of goat to play as silent L-BSE spreaders in natural conditions. However, we believe that prudence must be always adopted when dealing with the risk of prion spread in field conditions as also suggested by recent data by Denkers and colleagues, who showed that the oral route of infection for chronic wasting disease in deer, may be much more efficient than previously thought [21]. Furthermore, although the mere presence of PrPsc is not indicative of a possible infectivity of the tissue, the finding of positivity in the lymphoreticular tissue must alert to the potential distribution of PrPsc in peripheral body regions which may increase the risks for humans. Bioassay of infectivity by inoculation of susceptible animals with brains of these goats may help to clarify this issue.
Based on the results achieved with this prion form and also other animal strains, it would be useful to consider the possibility to enlarge current diagnostic criteria to include, in defined conditions (e.g. very limited amounts of source tissue, or preclinical testing), the application of ultrasensitive diagnostic methods. This will not only improve the sensitivity of our surveillance systems but will also help to protect food chain from accidental spillovers of the agent of L-BSE.
Limitations
Te primary limitation of this work is that infectivity was not demonstrated by bioassay and the infectious titre was not determined. Therefore, we cannot comment the degree of risk for human.
Despite these limitations, this work specifically demonstrates prion-seeding activity in tissues of goats orally exposed to L-BSE and provide RT-QuIC as useful method to enhance surveillance of TSEs.
Keywords: Prion, L-BSE, RT-QuIC, Goat, Oral transmission, PrPsc, Ultrasensitive detection
snip...see full text;
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC8650279&blobtype=pdf
WEDNESDAY, DECEMBER 8, 2021
Importation of Sheep, Goats, and Certain Other Ruminants AGENCY: Animal APHIA, USDA, FINAL RULE [Docket No. APHIS–2009–0095] RIN 0579–AD10
snip...
WTF were they thinking...
Isolation of Prion with BSE Properties from Farmed Goat
***> Our data show that BSE can infect small ruminants under natural conditions and could be misdiagnosed as scrapie
wtf were they thinking...
snip...see full report ;
WEDNESDAY, DECEMBER 8, 2021
Importation of Sheep, Goats, and Certain Other Ruminants AGENCY: Animal APHIA, USDA, FINAL RULE [Docket No. APHIS–2009–0095] RIN 0579–AD10
https://animalhealthreportpriontse.blogspot.com/2021/12/importation-of-sheep-goats-and-certain.html
https://www.usda.gov/topics/animals/bse-surveillance-information-center
https://www.cdc.gov/prions/bse/case-us.html
TUESDAY, SEPTEMBER 07, 2021
Atypical Bovine Spongiform Encephalopathy BSE OIE, FDA 589.2001 FEED REGULATIONS, and Ingestion Therefrom
https://bse-atypical.blogspot.com/2021/09/atypical-bovine-spongiform.html
http://bovineprp.blogspot.com/2020/12/bse-research-project-final-report-2005.html
see full text;
MONDAY, DECEMBER 27, 2021
RT-QuIC detection of pathological prion protein in subclinical goats following experimental oral transmission of L-type BSE
https://bse-atypical.blogspot.com/2021/12/rt-quic-detection-of-pathological-prion.html
terry
