Gamma-Herpesvirus-Induced Cutaneous/Mucosal Proliferative Lesions in a Pygmy Sperm Whale (Kogia breviceps)
Herpesvirus infection in cetaceans has been reported worldwide, and all identiﬁed cetacean herpesviruses have been classified either into alpha-herpesvirinae or gamma-herpesvirinae subfamilies.1 Both alpha-herpesvirus and gamma-herpesvirus can cause cutaneous/mucosal lesions in cetaceans.2 This is the first case report describing cutaneous/mucosal proliferative lesions caused by gamma-herpesvirus in an adult male pygmy sperm whale (Kogia breviceps) found stranded in eastern Taiwan with severe parasitic infestation in blubber and skeletal muscle. The animal died after stranding, and necropsy with sample collection for molecular/histological examination was performed. There were numerous aggregates of nematode parasites in the blubber and skeletal muscle near the neck. On the tongue, oral mucosa, pharyngeal mucosa, penis, the skin/mucosa nearby genital slit, skin near the left cheek, there were numerous raised, verrucous and irregularly shaped masses, ranged from 0.5 to 2 cm diameter, and some of them coalesced to form a large plaque lesion. These masses were composed of hyperplastic stratified squamous epithelium, featured by a thick stratum spinosum and marked anastomosing/down growing rete ridges. The epithelial cells at the stratum germinativum showed hydropic degeneration. Ballooning degeneration and chromatin margination with the presence of intranuclear eosinophilic inclusion bodies were observed in the epithelial cells at the stratum spinosum. The nematode parasites had cuticle, pseudocoelom, coelomyarian musculature, and intestinal tract lined by numerous cuboidal cells with single nucleus (uninucleated epithelial cells), indicative of Ascaridida/Spirurida.3 Nested PCR targeting the region of the DNA polymerase gene of Herpesviridae by using universal primers was positive, and the PCR product was directly sequenced.1,4 The DNA sequences (353 and 138 bp) were most closely related to a gamma-herpesvirus (91% nucleotide identity) from vaginal slit lesions of dwarf sperm whales.1,4
The authors thank the professors and pathology residents, including Profs. Victor Fei Pang, Chian-Ren Jeng, Fun-In Wang, and Hui-Wen Chang, and Drs. Cheng-Shun Hsueh, Phoebe Chi-Fei Kao, and Cheng-Hsin Shih at the Graduate Institute of Molecular and Comparative Pathobiology, National Taiwan University, for idea discussion. We truly appreciate the personnel and volunteers of Taiwan Cetacean Society for dealing with every stranding event in Taiwan. Furthermore, we acknowledge the Forestry Bureau, Council of Agriculture and Ocean Conservation Administration, Ocean Affairs Council, executive yuan for the financial support.
* Presenting author
1. Sacristan C, Esperon F, Ewbank AC, Diaz-Delgado J, Ferreira-Machado E, Costa-Silva S, Sanchez-Sarmiento AM, Groch KR, Neves E, Pereira Dutra GH. 2018. Novel herpesviruses in riverine and marine cetaceans from South America. Acta Trop. 190:220–227.
2. Sierra E, Sanchez S, Saliki JT, Blas-Machado U, Arbelo M, Zucca D, Fernandez A. 2014. Retrospective study of etiologic agents associated with nonsuppurative meningoencephalitis in stranded cetaceans in the Canary Islands. J Clin Microbiol. 52:2390–2397.
3. Foreyt B. 2001. Veterinary Parasitology Reference Manual. Iowa: Iowa State University Press.
4. Smolarek Benson KA, Manire CA, Ewing RY, Saliki JT, Townsend FI, Ehlers B, Romero CH. 2006. Identification of novel alpha- and gamma-herpesviruses from cutaneous and mucosal lesions of dolphins and whales. J Virol Methods. 136:261–266.