Canadian 2021 H-type Bovine Spongiform Encephalopathy case associated with a novel E211K polymorphism in prion protein gene novel E211K polymorphism in prion protein geneCanadian 2021 H-type Bovine Spongiform Encephalopathy case associated with a novel E211K polymorphism in prion protein gene novel E211K polymorphism in prion protein gene
Published online: 04 Aug 2025
ABSTRACT
Bovine Spongiform Encephalopathy (BSE) is a fatal neurodegenerative disease in cattle which can be either classical BSE (C-BSE) or atypical BSE (including H-BSE and L-BSE). Here, we report the results of our analyses of an H-BSE case found in Canada in 2021, indicating restriction of the pathological agent (PrPSc) mainly to the central nervous system with no or occasional weak involvement of peripheral tissues. Importantly, a non-synonymous mutation at codon 211 of the PRNP gene was detected and confirmed to be present as a germline mutation. This is the first case of BSE in Canada with a predisposing E211K mutation.
Snip
Canada has reported 3 cases of atypical BSE (in addition to 17 cases of C-BSE) to date, with 1 case of L-BSE (in December 2007) and 2 cases of H-BSE (first one in July 2006 and the most recent in December 2021). There were no genetic risk factors or pathogenic mutations identified in the first two atypical BSE cases in Canada [Citation23]. Here, we report the results of our analyses of the most recent H-BSE case (Canadian BSE case 20), where we investigated, i) the spatial distribution of PrPSc to assess any changes in specified risk material (SRM), and ii) the genetic risk factors contributing to the sporadic disease onset in this case of H-BSE.
Snip…
Regarding the origin of H-BSE cases, most of those reported worldwide have been sporadic except for one in the 2006 US H-BSE case associated with the E211K mutation [Citation18]. Canada has reported a total of 20 cases of BSE to date which included 17 C-BSE, 1 L-BSE, and 2 H-BSE cases. The only L-BSE case was identified in December 2007. The first case of H-BSE was identified in July 2006 and the latest case in December 2021.
snip…
The DNA sequencing results of the Canadian BSE case 20 also showed no variation in the number of OPRs of the PRNP gene just like the previous Canadian BSE cases indicating a very low risk of such genetic variations in the Canadian cattle herd. Similarly, none of the synonymous mutations at codon 23 (L23L; CTC/CTA or CTG), 78 (Q78Q; CAG/CAA), 113 (P113P; CCC/CCT) and 185 (N185N; AAC/AAT), which were reported previously in the French, American, Swedish, Canadian and Portuguese H-BSE cases [Citation23,Citation35–38], were identified in the Canadian BSE case 20. Though a synonymous mutation at codon 192 (N192N; AAC/AAT) was detected in the Canadian BSE case 20, it was not a major concern because this mutation was also described previously in above mentioned studies and has no association with BSE. However, the detection of the E211K mutation in the Canadian BSE case 20 raises concerns because the E211K mutation has been associated with an increased susceptibility to H-BSE [Citation22] and is genetically inheritable to its offspring [Citation21], indicating that the E211K mutation could result in additional BSE cases.
This is the first time that the E211K mutation has been found in a Canadian BSE case. Additionally, the detection of the E211K mutation in multiple tissues strongly suggested that the E211K mutation in the Canadian BSE case 20 is a germline mutation. This implies that the E211K mutation in the Canadian BSE case 20 is most likely heritable and may be present in 50% of the offspring of this cow. However, it is difficult to speculate from where the Canadian BSE case 20 acquired the E211K mutation. The mutation could be either spontaneous or inherited from a parent. Possible theories about the origin of this E211K mutation in the Canadian BSE case 20 could include that, i) this cow acquired E211K mutation spontaneously in its early embryonic development, ii) germ cells from one of its parents acquired this mutation spontaneously, iii) ancestors of this cow had this mutation in their line, or iv) this mutation was present in a population of this breed. To explore these possibilities, a strategic testing of various cattle breeds (including Red Poll) from different geographic regions within Canada is important and being planned. However, none of its ancestors were traceable or available for testing to explore if the Canadian BSE case 20 acquired the E211K mutation from its ancestors. On the other hand, irrespective of the detection of the E211K mutation in this Canadian cow, there will always be a slight possibility for the E211K mutation to occur independently in any cattle. Nonetheless, the presence of the E211K mutation in cattle makes them highly susceptible to develop H-BSE [Citation22]. While strong BSE mitigation measures such as specified risk material removal, and ruminant to ruminant feed bans play a major role in preventing future BSE cases, the potential for animals with the E211K mutation and an increased risk of developing atypical BSE in the Canadian cattle population cannot be ruled out.
The E211K mutation associated with the US H-BSE case was heritable [Citation21] and associated with an increased susceptibility to H-BSE, represented by a shorter incubation time in cattle with K211 allele during the experimental challenge studies [Citation22,Citation39], and suggested a higher propensity for the K211 prion protein to misfold. Identification of E211K mutation in the 2006 US and 2021 Canadian H-BSE cases represent independent existence of this pathogenic mutation in time and space. This is further supported by the comparative analysis (Supplementary Table S1) of both cases showing minor dissimilarities, though both cases were confirmed as H-type BSE. Those dissimilarities included the presence of 4th band of PK resistant PrP at 10 kDa in western-blot and a synonymous mutation at codon 192 of the PRNP gene in Canadian BSE cases 20 only. Additionally, proven heritability and germline nature of E211K mutation in the 2006 US and 2021 Canadian H-BSE cases respectively, indicate familial nature of E211K mutation just like familial Creutzfeldt Jakob's disease in humans. This highlights the importance of screening each identified case for genetic risk factors specifically and cattle population to determine the prevalence rate of E211K mutation in general, to eradicate this pathogenic mutation form the national herd.
After the detection of E211K mutation in the US H-BSE case in 2006, DNA testing of cattle populations was conducted in various countries including USA (n = 6062 cattle tested) [Citation40], China (n = 349) [Citation41], Poland (n = 105) [Citation42], Pakistan (n = 236 cattle and n = 281 buffalo) [Citation43] and Korea (n = 536) [Citation44], but no E211K mutation could be detected in any sample. This indicates that the E211K mutation in cattle is very rare. Notably, all the previously mentioned studies have largely analysed blood samples with only occasional testing of muscle or brain tissues to detect the E211K mutation, which might not be detected if it was present as a somatic or postzygotic mutation within a particular tissue. Recently, Won SY and colleagues novelly reported that the E211K mutation was present only in the medulla oblongata of three Holstein Korean slaughter cattle, was present at high rates and was a somatic mutation. In silico analyses of the biological impact of the E211K mutation in these cattle predicted that E211K was damaging in nature despite being a somatic mutation [Citation45]. Somatic mutations in the PRNP gene at codon D178N in sporadic CJD and P102L associated with sporadic Gerstmann – Sträussler – Scheinker (GSS) syndrome have also been documented in humans [Citation46,Citation47]. This indicates that the E211K mutation can be pathogenic irrespective of whether it is germline or somatic in origin. However, PrPSc was not detected in the medulla oblongata of the three Holstein Korean cattle carrying E211K as a somatic mutation, using highly sensitive in-vitro amplification assays including real-time quaking-induced conversion reactions (RT-QuIC) and protein misfolding cyclic amplification (PMCA) [Citation48]. Though more objective evidence is required to explore the possibility that a somatic E211K mutation can cause H-BSE, results from Kim YC and colleagues show that the level of somatic mutation required to induce H-BSE could be a determining factor. On the other hand, it could be argued that the three Holstein Korean cattle carrying a somatic E211K mutation had an average age of less than 5 years, and they might have acquired atypical BSE if they were let to live longer. While scientific evidence exist that E211K mutation increases susceptibility to H-BSE, however it is difficult to objectively conclude that E211K mutation is a bona fide mutation responsible for the onset of H- BSE. In this regard, a long-term project is already underway by the USDA to investigate the possibility of a genetic aetiology for H-BSE in cattle expressing the K211 allele. Based on the results of this study, and the 2006 H-BSE case in the USA, there is an expanded spectrum of aetiologies for bovine prion diseases similar to what is observed in humans, including sporadic, genetic and acquired versions.
https://www.tandfonline.com/doi/full/10.1080/19336896.2025.2511933#d1e1606
"Based on the results of this study, and the 2006 H-BSE case in the USA, there is an expanded spectrum of aetiologies for bovine prion diseases similar to what is observed in humans, including sporadic, genetic and acquired versions."
Published online: 04 Aug 2025
ABSTRACT
Bovine Spongiform Encephalopathy (BSE) is a fatal neurodegenerative disease in cattle which can be either classical BSE (C-BSE) or atypical BSE (including H-BSE and L-BSE). Here, we report the results of our analyses of an H-BSE case found in Canada in 2021, indicating restriction of the pathological agent (PrPSc) mainly to the central nervous system with no or occasional weak involvement of peripheral tissues. Importantly, a non-synonymous mutation at codon 211 of the PRNP gene was detected and confirmed to be present as a germline mutation. This is the first case of BSE in Canada with a predisposing E211K mutation.
Snip
Canada has reported 3 cases of atypical BSE (in addition to 17 cases of C-BSE) to date, with 1 case of L-BSE (in December 2007) and 2 cases of H-BSE (first one in July 2006 and the most recent in December 2021). There were no genetic risk factors or pathogenic mutations identified in the first two atypical BSE cases in Canada [Citation23]. Here, we report the results of our analyses of the most recent H-BSE case (Canadian BSE case 20), where we investigated, i) the spatial distribution of PrPSc to assess any changes in specified risk material (SRM), and ii) the genetic risk factors contributing to the sporadic disease onset in this case of H-BSE.
Snip…
Regarding the origin of H-BSE cases, most of those reported worldwide have been sporadic except for one in the 2006 US H-BSE case associated with the E211K mutation [Citation18]. Canada has reported a total of 20 cases of BSE to date which included 17 C-BSE, 1 L-BSE, and 2 H-BSE cases. The only L-BSE case was identified in December 2007. The first case of H-BSE was identified in July 2006 and the latest case in December 2021.
snip…
The DNA sequencing results of the Canadian BSE case 20 also showed no variation in the number of OPRs of the PRNP gene just like the previous Canadian BSE cases indicating a very low risk of such genetic variations in the Canadian cattle herd. Similarly, none of the synonymous mutations at codon 23 (L23L; CTC/CTA or CTG), 78 (Q78Q; CAG/CAA), 113 (P113P; CCC/CCT) and 185 (N185N; AAC/AAT), which were reported previously in the French, American, Swedish, Canadian and Portuguese H-BSE cases [Citation23,Citation35–38], were identified in the Canadian BSE case 20. Though a synonymous mutation at codon 192 (N192N; AAC/AAT) was detected in the Canadian BSE case 20, it was not a major concern because this mutation was also described previously in above mentioned studies and has no association with BSE. However, the detection of the E211K mutation in the Canadian BSE case 20 raises concerns because the E211K mutation has been associated with an increased susceptibility to H-BSE [Citation22] and is genetically inheritable to its offspring [Citation21], indicating that the E211K mutation could result in additional BSE cases.
This is the first time that the E211K mutation has been found in a Canadian BSE case. Additionally, the detection of the E211K mutation in multiple tissues strongly suggested that the E211K mutation in the Canadian BSE case 20 is a germline mutation. This implies that the E211K mutation in the Canadian BSE case 20 is most likely heritable and may be present in 50% of the offspring of this cow. However, it is difficult to speculate from where the Canadian BSE case 20 acquired the E211K mutation. The mutation could be either spontaneous or inherited from a parent. Possible theories about the origin of this E211K mutation in the Canadian BSE case 20 could include that, i) this cow acquired E211K mutation spontaneously in its early embryonic development, ii) germ cells from one of its parents acquired this mutation spontaneously, iii) ancestors of this cow had this mutation in their line, or iv) this mutation was present in a population of this breed. To explore these possibilities, a strategic testing of various cattle breeds (including Red Poll) from different geographic regions within Canada is important and being planned. However, none of its ancestors were traceable or available for testing to explore if the Canadian BSE case 20 acquired the E211K mutation from its ancestors. On the other hand, irrespective of the detection of the E211K mutation in this Canadian cow, there will always be a slight possibility for the E211K mutation to occur independently in any cattle. Nonetheless, the presence of the E211K mutation in cattle makes them highly susceptible to develop H-BSE [Citation22]. While strong BSE mitigation measures such as specified risk material removal, and ruminant to ruminant feed bans play a major role in preventing future BSE cases, the potential for animals with the E211K mutation and an increased risk of developing atypical BSE in the Canadian cattle population cannot be ruled out.
The E211K mutation associated with the US H-BSE case was heritable [Citation21] and associated with an increased susceptibility to H-BSE, represented by a shorter incubation time in cattle with K211 allele during the experimental challenge studies [Citation22,Citation39], and suggested a higher propensity for the K211 prion protein to misfold. Identification of E211K mutation in the 2006 US and 2021 Canadian H-BSE cases represent independent existence of this pathogenic mutation in time and space. This is further supported by the comparative analysis (Supplementary Table S1) of both cases showing minor dissimilarities, though both cases were confirmed as H-type BSE. Those dissimilarities included the presence of 4th band of PK resistant PrP at 10 kDa in western-blot and a synonymous mutation at codon 192 of the PRNP gene in Canadian BSE cases 20 only. Additionally, proven heritability and germline nature of E211K mutation in the 2006 US and 2021 Canadian H-BSE cases respectively, indicate familial nature of E211K mutation just like familial Creutzfeldt Jakob's disease in humans. This highlights the importance of screening each identified case for genetic risk factors specifically and cattle population to determine the prevalence rate of E211K mutation in general, to eradicate this pathogenic mutation form the national herd.
After the detection of E211K mutation in the US H-BSE case in 2006, DNA testing of cattle populations was conducted in various countries including USA (n = 6062 cattle tested) [Citation40], China (n = 349) [Citation41], Poland (n = 105) [Citation42], Pakistan (n = 236 cattle and n = 281 buffalo) [Citation43] and Korea (n = 536) [Citation44], but no E211K mutation could be detected in any sample. This indicates that the E211K mutation in cattle is very rare. Notably, all the previously mentioned studies have largely analysed blood samples with only occasional testing of muscle or brain tissues to detect the E211K mutation, which might not be detected if it was present as a somatic or postzygotic mutation within a particular tissue. Recently, Won SY and colleagues novelly reported that the E211K mutation was present only in the medulla oblongata of three Holstein Korean slaughter cattle, was present at high rates and was a somatic mutation. In silico analyses of the biological impact of the E211K mutation in these cattle predicted that E211K was damaging in nature despite being a somatic mutation [Citation45]. Somatic mutations in the PRNP gene at codon D178N in sporadic CJD and P102L associated with sporadic Gerstmann – Sträussler – Scheinker (GSS) syndrome have also been documented in humans [Citation46,Citation47]. This indicates that the E211K mutation can be pathogenic irrespective of whether it is germline or somatic in origin. However, PrPSc was not detected in the medulla oblongata of the three Holstein Korean cattle carrying E211K as a somatic mutation, using highly sensitive in-vitro amplification assays including real-time quaking-induced conversion reactions (RT-QuIC) and protein misfolding cyclic amplification (PMCA) [Citation48]. Though more objective evidence is required to explore the possibility that a somatic E211K mutation can cause H-BSE, results from Kim YC and colleagues show that the level of somatic mutation required to induce H-BSE could be a determining factor. On the other hand, it could be argued that the three Holstein Korean cattle carrying a somatic E211K mutation had an average age of less than 5 years, and they might have acquired atypical BSE if they were let to live longer. While scientific evidence exist that E211K mutation increases susceptibility to H-BSE, however it is difficult to objectively conclude that E211K mutation is a bona fide mutation responsible for the onset of H- BSE. In this regard, a long-term project is already underway by the USDA to investigate the possibility of a genetic aetiology for H-BSE in cattle expressing the K211 allele. Based on the results of this study, and the 2006 H-BSE case in the USA, there is an expanded spectrum of aetiologies for bovine prion diseases similar to what is observed in humans, including sporadic, genetic and acquired versions.
https://www.tandfonline.com/doi/full/10.1080/19336896.2025.2511933#d1e1606
"Based on the results of this study, and the 2006 H-BSE case in the USA, there is an expanded spectrum of aetiologies for bovine prion diseases similar to what is observed in humans, including sporadic, genetic and acquired versions."
