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From: TSS ()
Subject: Scrapie infectivity is quickly cleared in tissues of orally-infected farmed fish
Date: June 20, 2006 at 6:51 am PST

Research article

Scrapie infectivity is quickly cleared in tissues of orally-infected farmed fish

Loredana Ingrosso , Beatriz Novoa , Andrea Z Dalla Valle , Franco Cardone , Raquel Aranguren , Marco Sbriccoli , Simona Bevivino , Marcello Iriti , Quanguo Liu , Vito Vetrugno , Mei Lu , Franco Faoro , Salvatore Ciappellano , Antonio Figueras and Maurizio Pocchiari

BMC Veterinary Research 2006, 2:21 doi:10.1186/1746-6148-2-21


Published 15 June 2006


Abstract (provisional)

Background

Scrapie and bovine spongiform encephalopathy (BSE) belongs to the group of animal transmissible spongiform encephalopathy (TSE). BSE epidemic in the UK and elsewhere in Europe has been linked to the use of bovine meat and bone meals (MBM) in the feeding of cattle. There is concern that pigs, poultry and fish bred for human consumption and fed with infected MBM would eventually develop BSE or carry residual infectivity without disease. Although there has been no evidence of infection in these species, experimental data on the susceptibility to the BSE agent of farm animals other than sheep and cow are limited only to pigs and domestic chicken. In the framework of a EU-granted project we have challenged two species of fish largely used in human food consumption, rainbow trout (Oncorhynchus mykiss) and turbot (Scophthalmus maximus), with a mouse-adapted TSE strain (scrapie 139A), to assess the risk related to oral consumption of TSE contaminated food. In trout, we also checked the "in vitro" ability of the pathological isoform of the mouse prion protein (PrPSc) to cross the intestinal epithelium when added to the mucosal side of everted intestine.

Results

Fish challenged with a large amount of scrapie mouse brain homogenate by either oral or parenteral routes, showed the ability to clear the majority of infectivity load. None of the fish tissues taken at different time points after oral or parenteral inoculation was able to provoke scrapie disease after intracerebral inoculation in recipient mice. However, a few recipient mice were positive for PrPSc and spongiform lesions in the brain. We also showed a specific binding of PrPSc to the mucosal side of fish intestine in the absence of an active uptake of the prion protein through the intestinal wall.

Conclusions

These results indicate that scrapie 139A, and possibly BSE, is quickly removed from fish tissues despite evidence of a prion like protein in fish and of a specific binding of PrPSc to the mucosal side of fish intestine.

snip...

Conclusions

These data show that about 4 million LD50 of 139A given by forced feeding were readily removed from

fish intestine (both trout and turbot) in the first 24 hours after infection and that infection never reached

the brain, the spleen or the muscles. This suggests that scrapie is quickly removed from fish tissues

despite the presence of a cellular prion-like protein [15, 18] and a prion protein-like gene in fish [11,

12, 13]. With all the cautions due to the difference between the 139A and the BSE strains, and that in

this experiment fishes were observed for no more than 90 days after infection, it is tentatively possible

to assume that the consumption of fish fed with BSE-infected MBM should not pose any substantial

threat to public health.

snip...end...tss

http://www.biomedcentral.com/1746-6148/2/21

http://www.biomedcentral.com/content/pdf/1746-6148-2-21.pdf

re-Scrapie infectivity is quickly cleared in tissues of orally-infected farmed fish


Terry Singeltary (20 June 2006) http://disc.server.com/Indices/167318.html


>>>However, a few recipient mice were positive for PrPSc and spongiform lesions in the brain. We also showed a specific binding of PrPSc to the mucosal side of fish intestine in the absence of an active uptake of the prion protein through the intestinal wall. <<<

WOULD this not be further evidence to show that the rendering of such product after ingesting TSE tainted product, would further expose species that consume such product, i.e. even if the fish do not contract a TSE, could not the intestines and the feed that may still be there further expose species eating those by-products ???


Competing interests

none

http://www.biomedcentral.com/1746-6148/2/21/comments#236546

TSS




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