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From: TSS (216-119-163-136.ipset45.wt.net)
In Reply to: 5TH COW GOES DOWN WITH CWD FROM THE STUDIES OF HAMIR ET AL ? posted by TSS on June 23, 2003 at 7:45 am:
HERE is Dr. Millers response on my posting of the 4th cow that went X-Mailer: Novell GroupWise Internet Agent 6.0.1 ######## Bovine Spongiform Encephalopathy The statement that 4 cattle have developed evidence of CWD transmission following intracerebral inoculation is correct because an additional animal has been found prion positive subsequent to the 2001 paper that presented preliminary findings after only 2 and a half years of observation. Following this message is a summary of the current status of our CWD cross-species transmission experiments in cattle and sheep. This information was prepared in anticipation of questions about these studies that we expected would be raised at the recent annual meeting of the U.S. Animal Health Association. I would like to correct one statement in the newspaper article that was attributed to me that is in error. I did not imply that our work thus far could be extrapolated to the situation with white-tailed deer and dairy cattle. While there is no indication that there should be any difference in susceptibility of beef versus dairy cattle, we do not know if the CWD agent in white-tailed deer would be equivalent to that obtained from mule deer. For that reason Dr. Hamir is now repeating the original experiment in cattle with brain suspension from affected white-tails as inoculum. Experimental Transmission of Chronic Wasting Disease (CWD) to Cattle and Sheep Progress report - October 15, 2002 Transmission of CWD (mule deer) to cattle: Background: In 1997, 13 calves were inoculated intracerebrally with brain suspension from mule deer naturally affected with CWD. During the first 3 years, 3 animals were euthanized 23, 24, and 28 months after inoculation because of weight loss (2) or sudden death (1). Although microscopic examination of the brains did not show classical lesions of transmissible spongiform encephalopathy (TSE), a specific TSE marker protein, PrPres, was detected by immunohistochemistry (IHC) and western blot . Detailed information on these animals has been published previously (A Hamir et al., J Vet Diagn Invest 13: 91-96, 2001). Update: During the 3rd and 4th years of observation, 5 additional animals have been euthanized because of health concerns (primarily chronic joint and foot problems). Although all tests for PrPres are not complete, IHC results indicate that 1 of these animals, necropsied 59 months after inoculation, was positive for PrPres. This animal (# 1746) had not been eating well for approximately 1 week prior to being found recumbent. At necropsy, significant gross lesions consisted of an oblique fracture of L1 vertebral arch with extension into the body, and moderate multifocal hemorrhagic ulceration in the abomasum. Microscopic examination of brain revealed a few isolated neurons with single or multiple vacuoles, but neither neuronal degeneration nor gliosis was observed. IHC revealed the presence of PrPres in sections from several areas of the brain. Summary of findings on this case and data from previous animals: Necropsy Survival Disease Clinical Histo- IHC SAF WB No. Route date period course signs pathology ________________________________________________________________ 1745 i/c 8/18/99 23m 2m + +/- + - + 1768 i/c 9/22/99 24m 3m + +/- + + + 1744 i/c 1/29/00 28m 3d +/- - + + + 1749 i/c 5/20/01 44m NA - - - NT NT 1748 i/c 6/27/01 45m NA - - - NT NT 1743 i/c 8/21/02 59m NA - - - Pending Pending 1741 i/c 8/22/02 59m NA - - - Pending Pending 1746 i/c 8/27/02 59m 7d +/- +/- + Pending Pending NT = not tested; IHC = immunohistochemistry for PrPres; SAF = scrapie associated fibrils; NA = not applicable; WB = Western blot (Prionics-Check); + = lesions or antigen present; - = lesions or antigen absent; +/- = signs/lesions equivocal; i/c = intracerebral; m = months; d = days. Summary: After 5 years of observation we have 4 CWD transmissions to cattle from a group of 13 inoculates. These animals, which were necropsied 23, 24, 28, and 59 months after inoculation, did not show the clinical signs or histopathologic lesions typical of a TSE, but PrPres was detected in brain samples. Four other animals that were necropsied during the 4th and 5th years of observation have not shown evidence of prion disease (although not all tests are complete) and the 5 remaining cattle are apparently healthy. Note that this study involved direct intracerebral inoculation of cattle with the CWD agent, which is an unnatural route of exposure. It is likely that transmission by a more natural route, such as oral exposure, would be much more difficult to accomplish. Cattle have been inoculated orally at the University of Wyoming with the same inoculum used for this experiment, and 5 years into the study these animals remain healthy. Experimental Transmission of CWD (mule deer) to sheep Eight Suffolk sheep from the NADC scrapie-free flock were inoculated intracerebrally with the CWD brain suspension used to inoculate cattle. PRNP genotyping showed that 4 of the sheep were QQ at codon 171 and the other four were QR. Two of the QQ sheep were euthanized during the 3rd year of observation. At necropsy one of these animals had a urethral obstruction and PrPres was not detected in brain or lymphoid tissues. The other sheep, necropsied 35 months after inoculation, showed clinical signs and histopathologic lesions that were indistinguishable from scrapie. IHC tests showed typical PrPres accumulations in brain, tonsil, and some lymph nodes. The 2 remaining QQ sheep and all 4 QR sheep are apparently healthy 39 months after inoculation. Summary: After 3 years of observation we have 1 transmission of CWD to a 171 QQ sheep. This animal, which was necropsied 35 months after inoculation, showed clinical signs and histopathologic lesions that were indistinguishable from scrapie. Another QQ sheep that was necropsied during the 3rd year showed no evidence of prion disease and all remaining sheep (2 QQ and 4 QR) are apparently healthy. >>> flounder@WT.NET 11/23/02 06:54PM >>> ######## Bovine Spongiform Encephalopathy 1: J Vet Diagn Invest 2001 Jan;13(1):91-6 Preliminary findings on the experimental transmission of chronic wasting disease agent of mule deer to cattle. Hamir AN, Cutlip RC, Miller JM, Williams ES, Stack MJ, Miller MW, O'Rourke KI, Chaplin MJ. National Animal Disease Center, ARS, USDA, Ames, IA 50010, USA. To determine the transmissibility of chronic wasting disease (CWD) to cattle and to provide information about clinical course, lesions, and suitability of currently used diagnostic procedures for detection of CWD in cattle, 13 calves were inoculated intracerebrally with brain suspension from mule deer naturally affected with CWD. Between 24 and 27 months postinoculation, 3 animals became recumbent and were euthanized. Gross necropsies revealed emaciation in 2 animals and a large pulmonary abscess in the third. Brains were examined for protease-resistant prion protein (PrP(res)) by immunohistochemistry and Western blotting and for scrapie-associated fibrils (SAFs) by negative-stain electron microscopy. Microscopic lesions in the brain were subtle in 2 animals and absent in the third case. However, all 3 animals were positive for PrP(res) by immunohistochemistry and Western blot, and SAFs were detected in 2 of the animals. An uninoculated control animal euthanized during the same period did not have PrP(res) in its brain. These are preliminary observations from a currently in-progress experiment. Three years after the CWD challenge, the 10 remaining inoculated cattle are alive and apparently healthy. These preliminary findings demonstrate that diagnostic techniques currently used for bovine spongiform encephalopathy (BSE) surveillance would also detect CWD in cattle should it occur naturally. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11243374&dopt=Abstract Sat, Nov 23, 2002 Scientists unsure if CWD can jump species By Jessica Bock Wausau Daily Herald jbock@wdhprint.com snip... Janice Miller, a veterinarian in charge of the experiment, said she believes previous research shows it is hard for the disease to be transmitted naturally from whitetail deer to dairy cattle. "Our study says nothing of how it could be transmitted in natural surroundings," she said. Miller has been studying the transmission of CWD from mule deer to cattle since 1997. Since then, chronic wasting disease was transmitted to four out of 13 cattle injected with brain tissue from naturally infected mule deer, she said. In Wyoming, Williams has been studying cattle that were given a concoction of diseased brain tissue orally, and five years into the study the animals remain healthy, Miller said. No one knows if chronic wasting disease could ever spread to another species through natural surroundings. "Our experience is that it's pretty hard to predict," Miller said. http://www.wausaudailyherald.com/wdhlocal/277564794712612.shtml greetings list, > Since then, chronic wasting disease was > transmitted to four out of 13 cattle is this a typo by the media or has another cow gone down with CWD since the preliminary findings were found? TSS ########### http://mailhost.rz.uni-karlsruhe.de/warc/bse-l.html ########## ######## ########### http://mailhost.rz.uni-karlsruhe.de/warc/bse-l.html ############
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