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Intralesional bovine papillomavirus DNA loads reflect severity of equine sarcoid disease

Authors

  • R. HARALAMBUS,

    1. Equine Clinic, VetSuisse Faculty, University of Berne, Laenggass-Strasse 120, CH-3012 Berne, Switzerland; Department of Biotechnology in Animal Production, IFA-Tulln, Konrad-Lorenz-Strasse 20, A-3430 Tulln, Austria;
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  • J. BURGSTALLER,

    1. Equine Clinic, VetSuisse Faculty, University of Berne, Laenggass-Strasse 120, CH-3012 Berne, Switzerland; Department of Biotechnology in Animal Production, IFA-Tulln, Konrad-Lorenz-Strasse 20, A-3430 Tulln, Austria;
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  • J. KLUKOWSKA-RÖTZLER,

    1. Equine Clinic, VetSuisse Faculty, University of Berne, Laenggass-Strasse 120, CH-3012 Berne, Switzerland; Department of Biotechnology in Animal Production, IFA-Tulln, Konrad-Lorenz-Strasse 20, A-3430 Tulln, Austria;
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  • R. STEINBORN,

    1. Vetomics Core Facility, University of Veterinary Medicine, Veterinaerplatz 1, A-1210;
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  • S. BUCHINGER,

    1. Faculty of Computer Science, University of Vienna, Lenaugasse 2/8, A-1080; and
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  • V. GERBER,

    1. Equine Clinic, VetSuisse Faculty, University of Berne, Laenggass-Strasse 120, CH-3012 Berne, Switzerland; Department of Biotechnology in Animal Production, IFA-Tulln, Konrad-Lorenz-Strasse 20, A-3430 Tulln, Austria;
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  • S. BRANDT

    1. Equine Biotechnology Unit, University of Veterinary Medicine, Veterinaerplatz 1, A-1210 Vienna, Austria.
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Summary

Reasons for performing study: Sarcoids are nonmetastasising, yet locally aggressive skin tumours that constitute the most frequent neoplasm in equids. Infection by bovine papillomaviruses types 1 and 2 (BPV-1, BPV-2) has been recognised as major causative factor in sarcoid pathogenesis, but a possible correlation of intralesional virus load with disease severity has not been established thus far.

Hypothesis: Given the pathogenic role of BPV-1 and BPV-2 in sarcoid disease, we suggest that intralesional viral DNA concentration may reflect the degree of affection.

Methods: Severity of disease was addressed by recording the tumour growth kinetics, lesion number and tumour type for 37 sarcoid-bearing horses and one donkey. Viral load was estimated via quantitative real-time PCR (qPCR) of the E2, E5, L1 and L2 genes from the BPV-1/-2 genome for one randomly selected lesion per horse and correlated with disease severity.

Results: Quantitative PCR against E2 identified viral DNA concentrations ranging from 0–556 copies/tumour cell. Of 16 horses affected by quiescent, slowly growing single tumours or multiple mild-type lesions, 15 showed a viral load up to 1.4 copies per cell. In stark contrast, all equids (22/22) bearing rapidly growing and/or multiple aggressive sarcoids had a viral load between 3 and 569 copies per cell. Consistent results were obtained with qPCR against E5, L1 and L2.

Conclusions: While tumours of the same clinical type carried variable virus load, confirming that viral titre does not determine clinical appearance, we identified a highly significant correlation between intralesional viral load and disease severity.

Potential relevance: The rapid determination of BPV viral load will give a reliable marker for disease severity and may also be considered when establishing a therapeutic strategy.

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