ORIGINAL RESEARCH article
Front. Vet. Sci., 10 March 2026 Sec. Veterinary Neurology and Neurosurgery Volume 13 - 2026 | https://doi.org/10.3389/fvets.2026.1782728
Novel polymorphisms and functional characterization of the prion protein gene in sparrows (Passer montanus)
C Chau-Giang Truong 1,2† D Da-In Choi 1,2† Byung-Hoon Jeong .jpeg Byung-Hoon Jeong 1,2* 1. Korea Zoonosis Research Institute, Jeonbuk National University, Iksan, Jeonbuk, Republic of Korea
2. Department of Bioactive Material Sciences, Jeonbuk National University, Jeonju, Jeonbuk, Republic of Korea Abstract
Background: Misfolding of the prion protein (PrP) into an aberrant conformation causes prion diseases in several mammalian species; however, no prion infections have been documented in birds so far. The prion protein gene (PRNP) has been extensively studied in mammals, but little is known about PRNP polymorphisms in avian species and their potential roles in resistance to prion pathogenesis. However, the genetic variation of the sparrow PRNP gene remains largely uncharacterized.Materials and
methods: To better understand the genetic diversity of PRNP gene in sparrows, we sequenced the coding region from genomic DNA of 44 individuals. We analyzed the genetic characteristics of the sparrow PRNP gene, including genotype, allele, and haplotype distributions, as well as linkage disequilibrium (LD) among single nucleotide polymorphisms (SNPs) and insertion/deletion (indel) variants. The functional effects of the identified polymorphisms were predicted using multiple in silico tools, including PolyPhen-2, SIFT, AMYCO, SODA, and MutPred-Indel. In addition, the structural impact of non-synonymous substitutions was assessed by structural modeling tools, and the amino acid sequences of the hexapeptide tandem repeat were compared across avian species.
Results: A total of 24 polymorphisms were identified in the sparrow PRNP gene, including 9 non-synonymous substitutions and 3 indels. Among these, the A121V substitution was predicted to have the most detrimental effect, causing pronounced structural perturbation and increased amyloid propensity of sparrow PrP. The L5P and W105R substitutions also showed potentially deleterious impacts on protein stability. Among the indel polymorphisms, c.190_207delAACCCGGGCTACCCCCAC and c.243_244insAACCCCGGCTACCCCCAC were predicted to reduce solubility, whereas c.225_226insAACCCGGGCTACCCCCAC increased solubility. Furthermore, sparrow PrP exhibited a comparable length to that of quail, with both species containing eight hexapeptide repeat units.
Conclusion: As far as we know, this study represents the first report of PRNP genetic polymorphisms in sparrows, providing baseline data for future studies on avian prion resistance.
snip…
4 Discussion Sparrows are one of the most prevalent avian species worldwide. To characterize the specific features of the sparrow PrP, we investigated the PRNP gene. In this study, we identified 25 novel polymorphisms in the sparrow PRNP gene, including 22 SNPs and 3 indel variants (Figures 1, 2). Such polymorphisms are of particular interest because PRNP variation in mammals has been closely linked to altered susceptibility to prion diseases (1, 2). Although sparrows are not known to develop prion diseases, identifying and characterizing these variants provides a valuable opportunity to explore how polymorphisms might shape PrP structure and function across species.
snip…
https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2026.1782728/full
“however, no prion infections have been documented in birds so far.”
SE1806
TRANSMISSION STUDIES OF BSE TO DOMESTIC FOWL BY ORAL EXPOSURE TO BRAIN HOMOGENATE
1 challenged cock bird was necropsied (41 months p.i.) following a period of ataxia, tremor, limb abduction and other neurological signs. Histopathological examination failed to reveal any significant lesions of the central or peripheral nervous systems...
snip...
94/01.19/7.1
http://www.bse.org.uk/files/yb/1994/01/19007001.pdf
*** New URL
https://web.archive.org/web/20090506013034/http://www.bseinquiry.gov.uk/files/yb/1994/01/19007001.pdf
also,
TRANSLATION
F437/91
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY -
* The Red-Neck Ostrich 'THE AUTOPSY' & TSEs
THE AUTOPSY
Date: Mon, 11 Jun 2001 16:24:51 -0700 Reply-To: Bovine Spongiform Encephalopathy Sender: Bovine Spongiform Encephalopathy From: "Terry S. Singeltary Sr." Subject: The Red-Neck Ostrich & TSEs 'THE AUTOPSY'
######## BSE #########
TRANSLATION
F437/91
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY -
H A Schoon, Doris Brunckhorst and J Pohienz Institute of Pathology, Veterinary University of Hannover
Introduction
Since the first appearance of BSE in Great Britain in l985 {review in TRUYEN & KAADEN, l990), research into the incidence, diagnosis, differential diagnosis and epidemiology of spongiform encephalopathies in humans and animals has been a focus of medical and public interest. In view of the growing number of reports of "new" spontaneously or experimentally susceptible species (cats: WYATT et al, l990; pigs: DAWSON et al, 1990), and of the associated questions with regard to the causal agent and in particular its transmissibility, it seems essential that agnopathogenetic individual cases should also be described. We therefore report below the preliminary findings of morphological examinations of three red-necked ostriches in 1986, 1988 and 1989, taking account of differential diagnostic factors.
History/subjects
The three ostriches (Flock A: Ostrich 1, female, adult, 150 kg; Flock B: Ostrich 2, female, adult, 80 kg; Ostrich 3: male, juvenile, 60 kg) came from two zoos in North West Germany and were euthenised because of their hopeless prognosis. Preliminary reports indicated that all three birds had presented protracted central nervous symptoms with ataxia, disturbance of balance and discoordinated feeding behaviour. Ostrich 2 had also exhibited pronounced lameness of the left lower limbs and the juvenile bird was suffering from perosis. The birds were fed on vegetable material, supplemented by commercial compound poultry feed and ''raw meat'', some of which was ''obtained from local small emergency slaughterers''. Comparable clinical pictures with fatal outcome in individual birds had occurred in both flocks: in a male bird at the same time (Flock A) and in several ostriches over recent years (Flock B).
Methods
Autopsy was followed in all three cases by histopathological examination of the following tissues: heart (several locations including coronary arteries and aorta), right and left pulmonary lobes, liver, kidneys, limb musculature, peripheral nerves (brachial plexus, sciatic nerve, in each case both left and right) and brain (left and right cerebral hemispheres, two samples each from the cranial/caudal third, two sagittal sections of the cerebellum, two cross-sections of the brain stem at the level of the optical lobes, four cross-sections from the medulla oblongata). The tissue material was fixed in formalin and embedded in Paraplast by the conventional method and the sections were evaluated using the following staining techniques and histochemical reactions: all organs: haematoxylin eosin staining; brain: PAS reaction (McManus), Ziehl/Neelsen staining (mod. Pearse), iron method (Lillie) for detection of neuromelanin, Turnbull's reaction (Bancroft & Stevens), alkaline Congo red method (Puchtler) (of SCOON & SCHINKEL, 1986), myelin sheath staining (Spielmeyer) (ROMEIS, 1968). In addition, unstained sections were examined by fluorescence microscopy (to detect autofluorescing lipofuscin granula) and the following lipid stains were applied to cryostat sections of liver, and of heart and skeletal musculature: Sudan III, Sudan black, oil red.
Findings
snip...
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY
http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf
https://web.archive.org/web/20060210125137/http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf
Subject: Red-Neck Ostrich and BSE TSE Prion
http://chronic-wasting-disease.blogspot.com/2013/07/could-avian-scavengers-translocate.html
http://chronic-wasting-disease.blogspot.com/2009/11/american-crows-corvus-brachyrhynchos.html
ALSO; in Harash Narang's book THE LINK (i believe he went to work for NIH on TSEs, not sure if he is still there) there is a part about BSE IN HENS (page 135), that a farmer in kent in Nov. 1996 noticed that one of his 20 free range hens the oldest, aged about 30 months, was having difficulty entering its den and appeared frightened and tended to lose its balance when excited. Having previously experiencing BSE cattle on his farm, he took particular notice of the bird and continued to observe it over the following weeks. It lost weight, its balance deteriorated and characteristic tremors developed which were closely associated with the muscles required for standing (Fig. 15). In its attempts to maintain its balance it would claw the ground more than usual and the ataxia progressively developed in the wings and legs, later taking a typical form of paralysis with a clumsy involuntary jerky motion. Violent tremors of the entire body, particularly the legs, similar to those seen in BSE, became common sparked off by the slightest provocation. Three other farmers from the UK are known to have reported having hens with similar symptoms...
with this agent, i would not rule out anything or any species...TSS
From: TSS Subject: TRANSMISSION STUDIES OF DOMESTIC FOWL AND OSTRICH...... Date: May 9, 2002 at 7:36 am PST
######## Bovine Spongiform Encephalopathy #########
Greetings List Members,
just reading over a few old documents, i am pondering a few things out loud here, hope some find them interesting...TSS
snip...
SE1806
TRANSMISSION STUDIES OF BSE TO DOMESTIC FOWL BY ORAL EXPOSURE TO BRAIN HOMOGENATE
1 challenged cock bird was necropsied (41 months p.i.) following a period of ataxia, tremor, limb abduction and other neurological signs. Histopathological examination failed to reveal any significant lesions of the central or peripheral nervous systems...
snip...
94/01.19/7.1
https://web.archive.org/web/20090506013034/http://www.bseinquiry.gov.uk/files/yb/1994/01/19007001.pdf
OPINION on : NECROPHAGOUS BIRDS AS POSSIBLE TRANSMITTERS OF TSE/BSE ADOPTED BY THE SCIENTIFIC STEERING COMMITTEE AT ITS MEETING OF 7-8 NOVEMBER 2002
OPINION
1. Necrophagous birds as possible transmitters of BSE. The SSC considers that the evaluation of necrophagous birds as possible transmitters of BSE, should theoretically be approached from a broader perspective of mammals and birds which prey on, or are carrion eaters (scavengers) of mammalian species. Thus, carnivorous and omnivorous mammals, birds of prey (vultures, falcons, eagles, hawks etc.), carrion eating birds (crows, magpies etc.) in general could be considered possible vectors of transmission and/or spread of TSE infectivity in the environment. In view also of the occurrence of Chronic Wasting Disease (CWD) in various deer species it should not be accepted that domestic cattle and sheep are necessarily the only source of TSE agent exposure for carnivorous species. While some information is available on the susceptibility of wild/exotic/zoo animals to natural or experimental infection with certain TSE agents, nothing is known of the possibility of occurrence of TSE in wild animal populations, other than among the species of deer affected by CWD in the USA.
1 The carrion birds are animals whose diet regularly or occasionally includes the consumption of carcasses, including possibly TSE infected ruminant carcasses.
C:\WINNT\Profiles\bredagi.000\Desktop\Necrophagous_OPINION_0209_FINAL.doc
http://ec.europa.eu/food/fs/sc/ssc/out295_en.pdf
-----------------------------------------------------
even the late great Dr. Gibbs once told me personally that even if the Chicken did not contract a TSE, IF the chicken had been fed the TSE tainted feed and then slaughtered, the agent survives the digestinal tract to pass on to other species through feed...
TSS
Date: Tue, 27 May 2003 08:07:58 -0500
Reply-To: Bovine Spongiform Encephalopathy
Sender: Bovine Spongiform Encephalopathy
From: "Terry S. Singeltary Sr."
Subject: FDA BSE Update - Pet Food from Canadian Manufacturer & MAD DOG DATA
######## Bovine Spongiform Encephalopathy #########
snip...see;
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY
https://web.archive.org/web/20090505211737/http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf
what if?
also,
TRANSLATION
F437/91
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY -
* The Red-Neck Ostrich 'THE AUTOPSY' & TSEs
THE AUTOPSY
Date: Mon, 11 Jun 2001 16:24:51 -0700 Reply-To: Bovine Spongiform Encephalopathy Sender: Bovine Spongiform Encephalopathy From: "Terry S. Singeltary Sr." Subject: The Red-Neck Ostrich & TSEs 'THE AUTOPSY'
######## BSE #########
TRANSLATION
F437/91
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY -
H A Schoon, Doris Brunckhorst and J Pohienz Institute of Pathology, Veterinary University of Hannover
Introduction
Since the first appearance of BSE in Great Britain in l985 {review in TRUYEN & KAADEN, l990), research into the incidence, diagnosis, differential diagnosis and epidemiology of spongiform encephalopathies in humans and animals has been a focus of medical and public interest. In view of the growing number of reports of "new" spontaneously or experimentally susceptible species (cats: WYATT et al, l990; pigs: DAWSON et al, 1990), and of the associated questions with regard to the causal agent and in particular its transmissibility, it seems essential that agnopathogenetic individual cases should also be described. We therefore report below the preliminary findings of morphological examinations of three red-necked ostriches in 1986, 1988 and 1989, taking account of differential diagnostic factors.
History/subjects
The three ostriches (Flock A: Ostrich 1, female, adult, 150 kg; Flock B: Ostrich 2, female, adult, 80 kg; Ostrich 3: male, juvenile, 60 kg) came from two zoos in North West Germany and were euthenised because of their hopeless prognosis. Preliminary reports indicated that all three birds had presented protracted central nervous symptoms with ataxia, disturbance of balance and discoordinated feeding behaviour. Ostrich 2 had also exhibited pronounced lameness of the left lower limbs and the juvenile bird was suffering from perosis. The birds were fed on vegetable material, supplemented by commercial compound poultry feed and ''raw meat'', some of which was ''obtained from local small emergency slaughterers''. Comparable clinical pictures with fatal outcome in individual birds had occurred in both flocks: in a male bird at the same time (Flock A) and in several ostriches over recent years (Flock B).
Methods
Autopsy was followed in all three cases by histopathological examination of the following tissues: heart (several locations including coronary arteries and aorta), right and left pulmonary lobes, liver, kidneys, limb musculature, peripheral nerves (brachial plexus, sciatic nerve, in each case both left and right) and brain (left and right cerebral hemispheres, two samples each from the cranial/caudal third, two sagittal sections of the cerebellum, two cross-sections of the brain stem at the level of the optical lobes, four cross-sections from the medulla oblongata). The tissue material was fixed in formalin and embedded in Paraplast by the conventional method and the sections were evaluated using the following staining techniques and histochemical reactions: all organs: haematoxylin eosin staining; brain: PAS reaction (McManus), Ziehl/Neelsen staining (mod. Pearse), iron method (Lillie) for detection of neuromelanin, Turnbull's reaction (Bancroft & Stevens), alkaline Congo red method (Puchtler) (of SCOON & SCHINKEL, 1986), myelin sheath staining (Spielmeyer) (ROMEIS, 1968). In addition, unstained sections were examined by fluorescence microscopy (to detect autofluorescing lipofuscin granula) and the following lipid stains were applied to cryostat sections of liver, and of heart and skeletal musculature: Sudan III, Sudan black, oil red.
Findings
snip...
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY
http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf
https://web.archive.org/web/20060210125137/http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf
Subject: Red-Neck Ostrich and BSE TSE Prion
http://chronic-wasting-disease.blogspot.com/2013/07/could-avian-scavengers-translocate.html
http://chronic-wasting-disease.blogspot.com/2009/11/american-crows-corvus-brachyrhynchos.html
ALSO; in Harash Narang's book THE LINK (i believe he went to work for NIH on TSEs, not sure if he is still there) there is a part about BSE IN HENS (page 135), that a farmer in kent in Nov. 1996 noticed that one of his 20 free range hens the oldest, aged about 30 months, was having difficulty entering its den and appeared frightened and tended to lose its balance when excited. Having previously experiencing BSE cattle on his farm, he took particular notice of the bird and continued to observe it over the following weeks. It lost weight, its balance deteriorated and characteristic tremors developed which were closely associated with the muscles required for standing (Fig. 15). In its attempts to maintain its balance it would claw the ground more than usual and the ataxia progressively developed in the wings and legs, later taking a typical form of paralysis with a clumsy involuntary jerky motion. Violent tremors of the entire body, particularly the legs, similar to those seen in BSE, became common sparked off by the slightest provocation. Three other farmers from the UK are known to have reported having hens with similar symptoms...
with this agent, i would not rule out anything or any species...TSS
From: TSS Subject: TRANSMISSION STUDIES OF DOMESTIC FOWL AND OSTRICH...... Date: May 9, 2002 at 7:36 am PST
######## Bovine Spongiform Encephalopathy #########
Greetings List Members,
just reading over a few old documents, i am pondering a few things out loud here, hope some find them interesting...TSS
snip...
SE1806
TRANSMISSION STUDIES OF BSE TO DOMESTIC FOWL BY ORAL EXPOSURE TO BRAIN HOMOGENATE
1 challenged cock bird was necropsied (41 months p.i.) following a period of ataxia, tremor, limb abduction and other neurological signs. Histopathological examination failed to reveal any significant lesions of the central or peripheral nervous systems...
snip...
94/01.19/7.1
https://web.archive.org/web/20090506013034/http://www.bseinquiry.gov.uk/files/yb/1994/01/19007001.pdf
OPINION on : NECROPHAGOUS BIRDS AS POSSIBLE TRANSMITTERS OF TSE/BSE ADOPTED BY THE SCIENTIFIC STEERING COMMITTEE AT ITS MEETING OF 7-8 NOVEMBER 2002
OPINION
1. Necrophagous birds as possible transmitters of BSE. The SSC considers that the evaluation of necrophagous birds as possible transmitters of BSE, should theoretically be approached from a broader perspective of mammals and birds which prey on, or are carrion eaters (scavengers) of mammalian species. Thus, carnivorous and omnivorous mammals, birds of prey (vultures, falcons, eagles, hawks etc.), carrion eating birds (crows, magpies etc.) in general could be considered possible vectors of transmission and/or spread of TSE infectivity in the environment. In view also of the occurrence of Chronic Wasting Disease (CWD) in various deer species it should not be accepted that domestic cattle and sheep are necessarily the only source of TSE agent exposure for carnivorous species. While some information is available on the susceptibility of wild/exotic/zoo animals to natural or experimental infection with certain TSE agents, nothing is known of the possibility of occurrence of TSE in wild animal populations, other than among the species of deer affected by CWD in the USA.
1 The carrion birds are animals whose diet regularly or occasionally includes the consumption of carcasses, including possibly TSE infected ruminant carcasses.
C:\WINNT\Profiles\bredagi.000\Desktop\Necrophagous_OPINION_0209_FINAL.doc
http://ec.europa.eu/food/fs/sc/ssc/out295_en.pdf
-----------------------------------------------------
even the late great Dr. Gibbs once told me personally that even if the Chicken did not contract a TSE, IF the chicken had been fed the TSE tainted feed and then slaughtered, the agent survives the digestinal tract to pass on to other species through feed...
TSS
Date: Tue, 27 May 2003 08:07:58 -0500
Reply-To: Bovine Spongiform Encephalopathy
Sender: Bovine Spongiform Encephalopathy
From: "Terry S. Singeltary Sr."
Subject: FDA BSE Update - Pet Food from Canadian Manufacturer & MAD DOG DATA
######## Bovine Spongiform Encephalopathy #########
snip...see;
A CONTRIBUTION TO THE NEUROPATHOLOGY OF THE RED-NECKED OSTRICH (STRUTHIO CAMELUS) - SPONGIFORM ENCEPHALOPATHY
https://web.archive.org/web/20090505211737/http://www.bseinquiry.gov.uk/files/sc/Seac10/tab06.pdf
what if?
terry
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