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Transmissibility studies of vacuolar changes in the rostral

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Research article Open Access T

Transmissibility studies of vacuolar changes in the rostral colliculus of pigs

Timm Konold*1,2, John Spiropoulos1, Melanie J Chaplin3, Leigh Thorne3, Yvonne I Spencer1, Gerald AH Wells1 and Steve AC Hawkins1 Address: 1Department of Pathology, Veterinary Laboratories Agency Weybridge, Woodham Lane, Addlestone, UK, 2Royal Veterinary College, Infection and Immunity Research Group, North Mymms, Hatfield, UK and 3Department of Molecular Pathogenesis and Genetics, Veterinary Laboratories Agency Weybridge, Woodham Lane, Addlestone, UK Email: Timm Konold* - [email protected]; John Spiropoulos - [email protected]; Melanie J Chaplin - [email protected]; Leigh Thorne - [email protected]; Yvonne I Spencer - [email protected]; Gerald AH Wells - [email protected]; Steve AC Hawkins - [email protected] * Corresponding author

Abstract Background:

Histopathological examinations of brains from healthy pigs have revealed localised vacuolar changes, predominantly in the rostral colliculus, that are similar to the neuropil vacuolation featured in the transmissible spongiform encephalopathies and have been described in pigs challenged parenterally with the agent causing bovine spongiform encephalopathy (BSE). Feedstuff containing BSE-contaminated meat and bone meal (MBM) may have been fed to pigs prior to the ban of mammalian MBM in feed of farmed livestock in the United Kingdom in 1996, but there is no evidence of the natural occurrence of a transmissible spongiform encephalopathy (TSE) in the domestic pig. Furthermore, experimental transmission of BSE to pigs by the oral route has been unsuccessful. A study was conducted to investigate whether the localised vacuolar changes in the porcine brain were associated with a transmissible aetiology and therefore biologically significant. Two groups of ten pigs were inoculated parenterally with vacuolated rostral colliculus from healthy pigs either born before 1996 or born after 1996. Controls included ten pigs similarly inoculated with rostral colliculus from New Zealand-derived pigs and nine pigs inoculated with a bovine BSE brain homogenate. Results: None of the pigs inoculated with rostral colliculus developed a TSE-like neurological disease up to five years post inoculation when the study was terminated, and disease-associated prion protein, PrPd, was not detected in the brains of these pigs. By contrast, eight of nine BSE-inoculated pigs developed neurological signs, two of which had detectable PrPd by postmortem tests. No significant histopathological changes were detected to account for the clinical signs in the PrPd-negative, BSE-inoculated pigs. Conclusion: The findings in this study suggest that vacuolation in the porcine rostral colliculus is not caused by a transmissible agent and is probably a clinically insignificant change. The presence of neurological signs in pigs inoculated with BSE without detectable PrPd raises the possibility that the BSE agent may produce a prion disease in pigs that remains undetected by the current postmortem tests.


SNIP...


Conclusion The findings suggest that vacuolation in the rostral colliculus is a common feature of porcine brains without causing evident clinical signs and does not represent a localised form of a transmissible spongiform encephalopathy. The presence of neurological signs in pigs challenged with BSE in the absence of detectable disease-associated prion protein or other visible pathological changes raises the possibility that the BSE agent may cause a chronic disease that remains undetected by current prion disease phenotypic definitions and postmortem tests.


http://www.biomedcentral.com/content/pdf/1746-6148-5-35.pdf



SEE FULL TEXT WITH COMMENTS AND TRANSMISSION STUDIES OF BSE TO PIGS HERE ;



Thursday, October 15, 2009

Transmissibility studies of vacuolar changes in the rostral colliculus of pigs

Research article Open Access


http://madporcinedisease.blogspot.com/2009/10/transmissibility-studies-of-vacuolar.html
 
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