BSE can infect small ruminants and could be misdiagnosed as scrapie.

Primary isolation of bovine spongiform encephalopathy (BSE) in RIII mice generates a lesion profile believed to be reproducible and distinct from that produced by classical scrapie. This profile, which is characterized by peaks at gray matter areas 1, 4 and 7 (dorsal medulla, hypothalamus and septal nuclei), is used to diagnose BSE on primary isolation. The aim of this study was to investigate whether the BSE agent could be present in sheep diagnosed with classical scrapie, using lesion profiles in RIII mice as a discriminatory method. Sixty-two positive scrapie field cases were collected from individual farms between 1996 and 1999 and bioassayed in RIII mice. Fifty-five of these isolates transmitted successfully to at least one mouse. Of the 31 that produced adequate data to allow lesion profile analysis, 10 showed a consistent profile with peaks at brain areas 1, 4 and 7. All inocula for this subgroup were derived from sheep of genotype ARQ/ARQ. While the 1-4-7-scrapie profile exhibited similarities to BSE in RIII mice at primary isolation, it was distinguishable based on histopathology, immunohistochemistry and cluster analysis. We conclude that caution should be taken to distinguish this profile from BSE and that additional parameters should be considered to reach a final diagnosis.

PEA3 is a member of a subfamily of ETS domain transcription factors which is regulated by a number of signaling cascades, including the mitogen-activated protein (MAP) kinase pathways. PEA3 activates gene expression and is thought to play an important role in promoting tumor metastasis and also in neuronal development. Here, we have identified the LIM domain protein LPP as a novel coregulatory binding partner for PEA3. LPP has intrinsic transactivation capacity, forms a complex with PEA3, and is found associated with PEA3-regulated promoters. By manipulating LPP levels, we show that it acts to upregulate the transactivation capacity of PEA3. LPP can also functionally interact in a similar manner with the related family member ER81. Thus, we have uncovered a novel nuclear function for the LIM domain protein LPP as a transcriptional coactivator. As LPP continually shuttles between the cell periphery and the nucleus, it represents a potential novel link between cell surface events and changes in gene expression. PEA3, ER81, and ERM comprise the PEA3 subfamily of ETS domain transcription factors (reviewed in references 9 and 10). These proteins show a high degree of sequence conservation within their ETS DNA-binding domains and also in an N-terminal acidic domain and the region C-terminal to the ETS domain. These proteins also exhibit a high level of evolutionary conservation with homologues of human PEA3 and ERM, having been identified in other vertebrates such as zebra fish (4, 26). Biologically, PEA3 subfamily members have been shown to be involved in a number of processes including neuronal pathfinding (1, 24) and to play an important role in HER2/Neu-mediated mammary oncogenesis (37). Developmentally, members of the PEA3 subfamily are important recipients of fibroblast growth factor signaling (11,27,33,34). Fibroblast growth factor signaling acts via activating the extracellular signal-regulated kinase/mitogen-activated protein (ERK/MAP) kinase pathway and leads to the upregulation of the expression of PEA3 subfamily members. In addition, the transcriptional activity of several family members is enhanced in response to ERK pathway activation (18,19,28). A number of target genes have been identified (reviewed in reference 9 and 10), including genes with important roles in tumor growth and metastasis such as COX-2 (16, 42) and MMP-1 (3).The LPP (lipoma-preferred partner) protein and zyxin, ajuba, LIMD1, and TRIP6 form a subfamily of LIM domain proteins that are characterized by the presence of three tandem C-terminal LIM domains (44). LPP was first isolated as part of a fusion protein created by chromosomal translocations, in which the C-terminal part of LPP is fused to the N terminus of HMGA2/HMGIC (32). This suggests an important role for LPP in tumorigenesis and, in particular, the C-terminal region containing the LIM domains. LPP is usually localized at the cell periphery in focal adhesions and cell-cell contacts, where it associates with proteins such as ␣-actinin (23) and Scrib (31). However, in common with...

It is currently believed that primary transmission of classical scrapie to wild-type mice is inefficient and characterized by low attack rates and variable incubation periods and lesion profiles. Consequently, strain characterization of classical scrapie in these mice relies on subpassage. The aim of this study was to perform a retrospective analysis of lesion profiles and immunohistochemistry patterns after transmission of a large number of classical scrapie sources to wild-type mice and to investigate trends that might be used to characterize the agent without subpassaging. Scrapie field cases (n = 31) collected from individual farms between 1996 and 1999 were inoculated into RIII, C57BL, and VM mice and profiled using standard methodology and analyzed by immunohistochemistry. Using cluster analysis to resultant lesion profiles produced groups of similar lesion profiles in RIII and C57BL mice. We observed correlations between lesion profile clusters and the ovine prion protein (PrP) genotype. Immunohistochemistry indicated donor-mediated trends in the PrP pattern. These results indicate that ovine PrP genotype is a factor that is linked to both the lesion profile and the pattern of PrP deposition on primary transmission of classical scrapie to wild-type mice.

Two cases of unusual transmissible spongiform encephalopathy (TSE) were diagnosed on the same farm in ARQ/ARQ PrP sheep showing attributes of both bovine spongiform encephalopathy (BSE) and scrapie. These cases, UK-1 and UK-2, were investigated further by transmissions to wild-type and ovine transgenic mice. Lesion profiles (LP) on primary isolation and subpassage, incubation period (IP) of disease, PrPSc immunohistochemical (IHC) deposition pattern and Western blot profiles were used to characterize the prions causing disease in these sheep. Results showed that both cases were compatible with scrapie. The presence of BSE was contraindicated by the following: LP on primary isolation in RIII and/or MR (modified RIII) mice; IP and LP after serial passage in wild-type mice; PrPSc deposition pattern in wild-type mice; and IP and Western blot data in transgenic mice. Furthermore, immunohistochemistry (IHC) revealed that each case generated two distinct PrPSc deposition patterns in both wild-type and transgenic mice, suggesting that two scrapie strains coexisted in the ovine hosts. Critically, these data confirmed the original differential IHC categorization that these UK-1 and UK-2 cases were not compatible with BSE.