No H- and L-type cases in Belgium in cattle diagnosed with bovine spongiform encephalopathy (1999-2008) aging seven years and older.
BACKGROUND
The bovine spongiform encephalopathy (BSE) epidemic presented homogeneity of the phenotype. This classical BSE (called C-type) was probably due to the contamination of the food chain by a single prion strain. However, due to the active surveillance and better techniques, two rare variants of BSE have been recently reported in different continents without a clear correlation to the BSE epidemic. These emerging types behave as different strains of BSE and were named H-type and L-type according to the high and low molecular mass of the unglycosylated fragment of their proteinase K resistant prion protein (PrPres). In these types, the proportion of the un-, mono- and di-glycosylated fragments of PrP (glycoprofile) is also atypical and represents an effective diagnostic parameter. This study evaluated the presence of such types in bovine of 7 years and older in Belgium.


RESULTS
The Belgian BSE archive contained 41 bovines of at least 7 years of age. The biochemical features of their PrPres were analyzed by Western blot with five antibodies recognising different regions of PrPres, from N- to C-terminus: 12B2, 9A2, Sha31, SAF84 and 94B4. All antibodies clearly detected PrPres except 12B2 antibody, which is specific for N-terminal region 101-105, a PrP region that is only retained in H-types. The glycoprofiles did correspond to that of C-type (with more than 55% of diglycosylated PrPres using antibody 94B4). Therefore, all cases have the features of C-type BSE.


CONCLUSIONS
This study supports that, among the BSE cases of 7 years and older identified in Belgium, none was apparently of the H- or L- type. This is consistent with the very rare occurrence of atypical BSE and the restricted dimension of Belgium. These results shed some light on the worldwide prevalence of atypical BSE.
Dobly
Alexandre
A
Veterinary and Agrochemical Research Centre, Brussels, Belgium. aldob@var.fgov.be
Langeveld
Jan
J
van Keulen
Lucien
L
Rodeghiero
Caroline
C
Durand
Stéphanie
S
Geeroms
Riet
R
Van Muylem
Patrick
P
De Sloovere
Jessica
J
Vanopdenbosch
Emmanuel
E
Roels
Stefan
S
D000375:Aging; D000818:Animals; D001530:Belgium / Q000453:epidemiology; D002417:Cattle; D016643:Encephalopathy, Bovine Spongiform / Q000145:classification / Q000453:epidemiology* / Q000378:metabolism; D015995:Prevalence