Viral etiology of orogenital papillomatosis and squamous cell carcinoma in bottlenose dolphins in the southeastern United States.

Orogenital papillomatosis and squamous cell carcinoma is an emerging yet poorly understood complex disease of bottlenose dolphins (Tursiops truncatus and T. erebennus), both in the wild and under managed care. Previous studies have indicated a potential role of papillomaviruses and/or herpesviruses in the development of oncogenesis, although unbiased metagenomic approaches to examine the disease-associated virome in biopsied lesions have not been performed. Herein, we determined the viruses present in oral and genital lesions from both wild and managed care bottlenose dolphins from the southeastern United States through deep sequencing. The sampled dolphins were infected with two closely related but phylogenetically distinct lineages of delphinid gammaherpesvirus. Multiple different papillomaviruses were also detected, including a new species and several novel types of Tursiops papillomaviruses. Delphinid gammaherpesviruses were detected more often and at higher levels than papillomaviruses in both wild and managed care dolphins, although co-infections with both viruses were common. Additionally, we demonstrate that oral and genital swabs are an effective method for detecting viral infection in dolphins with or without lesions, providing a simple, non-invasive surveillance tool and an adjunct to surgical tissue biopsies. To build diagnostic tools for further study on viral diseases of bottlenose dolphins, we immortalized primary cells from oral frenulum biopsies via retroviral transduction of the simian virus 40 large T antigen gene, which was confirmed by immunoassays and chromosomal mapping. Elucidating the etiologic agent(s) and malignant transformation process of this important disease of dolphins may ultimately lead to the development of targeted therapeutics and/or preventative recommendations.