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Open Access Research article

Evaluation of two sets of immunohistochemical and Western blot confirmatory methods in the detection of typical and atypical BSE cases

Chiara Porcario1, S Mark Hall2*, Francesca Martucci1, Cristiano Corona1, Barbara Iulini1, Alice Z Perazzini1, Pierluigi Acutis1, Amir N Hamir34, Christina M Loiacono2, Justin J Greenlee3, Jürgen A Richt35, Maria Caramelli1 and Cristina Casalone1*

Author Affiliations

1 CEA, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via Bologna 148, 10154, Turin, Italy

2 United States Department of Agriculture, Animal and Plant Health Inspection Service (APHIS), National Veterinary Services Laboratories (NVSL), Pathobiology Laboratory, 1920 Dayton Ave, Ames, IA, 50010, USA

3 Virus and Prion Research Unit, National Animal Disease Center, United States Department of Agriculture, Agricultural Research Service (ARS), 1920 Dayton Ave, Ames, IA, 50010, USA

4 M. D. Anderson Cancer Center, Department of Veterinary Medicine and Surgery - Unit 63, 1515 Holcombe Boulevard, Room TB.4055C, Houston, TX 77030-4009, USA

5 K224B Mosier Hall College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5601, USA

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BMC Research Notes 2011, 4:376  doi:10.1186/1756-0500-4-376

Published: 29 September 2011

Abstract

Background

Three distinct forms of bovine spongiform encephalopathy (BSE), defined as classical (C-), low (L-) or high (H-) type, have been detected through ongoing active and passive surveillance systems for the disease.

The aim of the present study was to compare the ability of two sets of immunohistochemical (IHC) and Western blot (WB) BSE confirmatory protocols to detect C- and atypical (L- and H-type) BSE forms.

Obex samples from cases of United States and Italian C-type BSE, a U.S. H-type and an Italian L-type BSE case were tested in parallel using the two IHC sets and WB methods.

Results

The two IHC techniques proved equivalent in identifying and differentiating between C-type, L-type and H-type BSE. The IHC protocols appeared consistent in the identification of PrPSc distribution and deposition patterns in relation to the BSE type examined. Both IHC methods evidenced three distinct PrPSc phenotypes for each type of BSE: prevailing granular and linear tracts pattern in the C-type; intraglial and intraneuronal deposits in the H-type; plaques in the L-type.

Also, the two techniques gave comparable results for PrPSc staining intensity on the C- and L-type BSE samples, whereas a higher amount of intraglial and intraneuronal PrPSc deposition on the H-type BSE case was revealed by the method based on a stronger demasking step.

Both WB methods were consistent in identifying classical and atypical BSE forms and in differentiating the specific PrPSc molecular weight and glycoform ratios of each form.

Conclusions

The study showed that the IHC and WB BSE confirmatory methods were equally able to recognize C-, L- and H-type BSE forms and to discriminate between their different immunohistochemical and molecular phenotypes. Of note is that for the first time one of the two sets of BSE confirmatory protocols proved effective in identifying the L-type BSE form. This finding helps to validate the suitability of the BSE confirmatory tests for BSE surveillance currently in place.