Pathological and Immunohistochemical Analyses of Naturally Occurring Equine Glanders Using an Anti-BpaB Antibody.
Authors: Erdemsurakh Ochbayar, Purevdorj Baatarjargal, Ochirbat Khurtsbaatar, Adilbish Altanchimeg, Vanaabaatar Batbaatar, Aoshima Keisuke, Kobayashi Atsushi, Kimura Takashi
Journal: Veterinary pathology
Summary
# Editorial Summary: Pathological and Immunohistochemical Analyses of Naturally Occurring Equine Glanders Glanders, caused by the gram-negative bacterium *Burkholderia mallei*, remains a notifiable disease of significant concern in endemic regions, yet detailed characterisation of naturally infected tissue remains limited. Ochbayar and colleagues examined four Mongolian horses presenting with classic clinical signs—nasal discharge coupled with multiple cutaneous nodules on the hindlimbs and abdomen—using complement fixation, Rose Bengal agglutination, and mallein testing to confirm diagnosis, followed by histopathological examination and immunohistochemical staining with a monoclonal antibody targeting the bacterial BpaB antigen. The bacterium localised predominantly within immune cells, particularly neutrophils, macrophages, epithelioid cells, and multinucleated giant cells within pyogranulomas and abscesses affecting target organs; bacterial antigen was also detected in some alveolar type II cells and bronchiolar epithelial cells. These findings establish that anti-BpaB antibody staining reliably identifies infected cell populations in naturally occurring cases, offering practitioners and pathologists a valuable diagnostic tool for confirming the intracellular location and distribution of *B. mallei* in suspect tissue samples. For clinicians in affected regions, this work reinforces the importance of recognising cutaneous and respiratory manifestations as sentinel signs requiring urgent confirmatory testing and biosecurity measures.
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Practical Takeaways
- •Glanders remains a serious infectious disease in equine populations; horses with persistent nasal discharge and cutaneous nodules in hindlimbs/abdomen should be tested immediately using complement fixation, Rose Bengal agglutination, and mallein tests
- •Immunohistochemical analysis using anti-BpaB antibodies provides a reliable diagnostic tool for confirming B. mallei infection in tissue samples when clinical diagnosis is uncertain
- •This is a reportable disease in most countries; any confirmed or suspected cases require immediate notification to regulatory authorities and stringent biosecurity measures
Key Findings
- •Four horses in Mongolia with clinical glanders showed B. mallei antigen localization in neutrophils, macrophages, epithelioid cells, and multinucleated giant cells within pyogranulomas and abscesses
- •Anti-BpaB monoclonal antibody successfully identified B. mallei in infected alveolar type II cells and bronchiolar epithelial cells in naturally infected horses
- •Histopathological lesions were consistent with previously reported equine glanders cases, confirming typical disease presentation