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From: TSS ()
Subject: Polygenic variation and transmission factors involved in the resistance/susceptibility to scrapie in a Romanov flock
Date: February 19, 2005 at 9:04 am PST

-------- Original Message --------
Subject: Polygenic variation and transmission factors involved in the resistance/susceptibility to scrapie in a Romanov flock
Date: Fri, 18 Feb 2005 20:15:06 -0600
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy
To: BSE-L@LISTSERV.KALIV.UNI-KARLSRUHE.DE


##################### Bovine Spongiform Encephalopathy #####################

© 2005 Society for
General Microbiology


Polygenic variation and transmission factors involved in the
resistance/susceptibility to scrapie in a Romanov flock

Clara Díaz1, Zulma G. Vitezica2, Rachel Rupp2, Olivier Andréoletti3 and
Jean Michel Elsen2

1 Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria
(INIA), Dpto Mejora Genética Animal, Ctra de la Coruña km 7,5, 28040
Madrid, Spain
2 INRA, Station d'Amélioration Génétique des Animaux, Castanet Tolosan,
France
3 Ecole Vétérinaire de Toulouse, Interactions Hôtes-Agents Pathogènes,
31076 Toulouse, France

Correspondence
Clara Díaz
cdiaz@inia.es

Data from 4049 Romanov sheep belonging to a flock affected by natural
scrapie were analysed by using survival-analysis techniques. Failure
time was defined as the period of time between first exposure to
infection and the date that animals left the flock with scrapie signs.
Four hundred and forty-seven sheep were identified as ‘scrapie animals’.
Several models, including level of exposure as a time-dependent effect,
PrP genotype, sex, age at first exposure, litter size and factors
related to vertical transmission, were tested. The best model was
extended to a sire–dam frailty model, in order to estimate the polygenic
variation in addition to that in the Prnp gene. A combined effect of
rearing type and the dam's disease status was detected. Thus, only sheep
with a low degree of exposure to infection as lambs (lambs reared
artificially and born out of a healthy dam) showed less risk than
others. Animals first exposed to infection at older ages seemed to be
less susceptible to scrapie. In this Romanov population, new genotypes
(AHQ/AHQ, AHQ/VRQ, ARR/VRQ and ARR/ARQ) were associated with risk,
suggesting the effect of genotypes on the incubation period of animals.
Polygenic variance was responsible for 21 % of the total genetic
variability that was related to susceptibility to scrapie. Therefore,
the genetic susceptibility to scrapie may be explained by the joint
effect of point mutations at the Prnp major gene and a number of genes
that modulate its effect.

http://vir.sgmjournals.org/cgi/content/abstract/86/3/849?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=prion&searchid=1108778143595_1188&stored_search=&FIRSTINDEX=0&volume=86&issue=3&search_url=http%3A%2F%2Fvir.sgmjournals.org%2Fcgi%2Fsearch

TSS

######### https://listserv.kaliv.uni-karlsruhe.de/warc/bse-l.html ##########






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