Histopathological, Immunohistochemical and Ultrastructural Evidence of Herpesviral Infection in Skin and Tonsil of a Beluga Whale
Herpes-like viral infection has been rarely reported in beluga whales. In a captive beluga, Barr et al 1 found herpes-like viral particles by electron microscopy in a skin lesion which contained epithelial intranuclear inclusion bodies. Martineau et al2 reported a severe necrotizing dermatitis associated with a herpesvirus-like particle in a stranded beluga whale from a polluted area of the St. Lawrence River, Canada. Recently, we found a similar lesion in the skin of a beluga whale which stranded dead off South Portland, Maine. At necropsy, a focus of proliferative depigmented skin was found dorsal to the genital slit. Histopathologic examination revealed lymphoplasmacytic and proliferative dermatitis associated with epidermal intracellular edema and numerous prominent herpes-like eosinophilic intranuclear inclusion bodies, similar to that reported by Barr. Additionally, tonsillar epithelium contained similar foci of intracellular edema, with no or minimal inflammation; intranuclear inclusions were not observed in this location. Immunohistochemical staining for latent membrane protein of Epstein-Barr virus, a gammaherpesvirus, showed positive immunoreactivity in both epidermal and tonsillar epithelial lesions. By electron microscopy, virus particles morphologically consistent with herpesviruses were demonstrated in the skin lesion. The histopathologic findings in this beluga whale were strikingly similar to those reported by Lipscomb et al 3 in metastatic genital carcinomas in California sea lions, which was associated with the presence of a novel gammaherpesvirus. We are pursuing additional methods to further investigate the identification of the virus putatively associated with this lesion in beluga whales.
The authors are grateful to Mr. H. John Jenkins of the Armed Forces Institute of Pathology for outstanding electron microscopy support.
1. Barr B, JL Dunn, MD Daniel, A Banford. 1989. Herpes-like viral dermatitis in a beluga whale (Delphinapterus leucas). Journal of Wildlife Diseases, 25(4), pp. 608-611.
2. Martineau D, A Lagace, P Beland, R Higgins, D Armstrong, LR Shugart. Pathology of stranded beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Quebec, Canada. 1988. Journal of Comparative Pathology, 98(3), pp. 287-311.
3. Lipscomb TP, DP Scott, RL Garber, AE Krafft, MM Tsai, JH Lichy, JK Taubenberger, FY Schulman, FMD Gulland. Common metastatic carcinoma of California sea lions (Zalophus californianus): Evidence of genital origin and association with novel gammaherpesvirus. Veterinary Pathology, 37(6), pp. 609-617.