Use of a Western blot technique for the serodiagnosis of glanders

Mandy C Elschner,Gernot Schmoock,Renate Wernery,Holger C Scholz,Falk Melzer,Astrid Rassbach,Heinrich Neubauer,Ulrich Wernery,Muhammad Saqib,Marcilia Ma De Souza,Michael Dietzsch,Peggy Marten,Vania L De Assis Santana

doi:10.1186/1746-6148-7-4

Abstract

BackgroundThe in vivo diagnosis of glanders relies on the highly sensitive complement fixation test (CFT). Frequently observed false positive results are troublesome for veterinary authorities and cause financial losses to animal owners. Consequently, there is an urgent need to develop a test with high specificity. Hence, a Western blot assay making use of a partly purified lipopolysaccaride (LPS) containing antigen of three Burkholderia mallei strains was developed. The test was validated investigating a comprehensive set of positive and negative sera obtained from horses and mules from endemic and non endemic areas.ResultsThe developed Western blot assay showed a markedly higher diagnostic specificity when compared to the prescribed CFT and therefore can be used as a confirmatory test. However, the CFT remains the test of choice for routine testing of glanders due to its high sensitivity, its feasibility using standard laboratory equipment and its worldwide distribution in diagnostic laboratories.ConclusionsThe CFT should be amended by the newly validated Western blot to increase the positive likelihood ratio of glanders serodiagnosis in non endemic areas or areas with low glanders prevalence. Its use for international trade of horses and mules should be implemented by the OIE.

Highlights

The in vivo diagnosis of glanders relies on the highly sensitive complement fixation test (CFT)
Glanders, caused by Burkholderia (B.) mallei, is a highly contagious disease in equines which is notifiable to the World Organisation of Animal Health (OIE, Office International des Epizooties)
The diagnosis of B. mallei infection still relies on serological proof by agglutination test and complement fixation test (CFT), or proof of the presence of a specific delayed hypersensitivity reaction after intracutaneous application of mallein [12,13]

Summary

Introduction

The in vivo diagnosis of glanders relies on the highly sensitive complement fixation test (CFT). The CFT for glanders is so far the only officially recognized serological test in Glanders was eradicated from Western Europe, Australia and North America in the last century applying a rigorous culling of horses found positive in complement fixation and mallein test [15,19]. These techniques are useful in eradication programs with regard to specificity and sensitivity [12]. Current protocols for the extraction and purification of LPS from B. mallei are time consuming, sophisticated and hazardous for the operator [23,24]

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Discussion

Conclusion