Is herpesvirus infection in green sea turtles (Chelonia mydas) associated with the benign tumor disease fibropapillomatosis?

Emerging infectious diseases pose severe threats to wildlife heath and contribute to species declines and extinctions at a rate that indicates a sixth mass extinction may be under way. Marine turtle fibropapillomatosis (FP) is... [ view full abstract ]

Emerging infectious diseases pose severe threats to wildlife heath and contribute to species declines and extinctions at a rate that indicates a sixth mass extinction may be under way. Marine turtle fibropapillomatosis (FP) is an infectious neoplastic disease that is linked to a chelonid fibropapilloma-associated herpesvirus (CFPHV). FP was first documented in 1982 and causes cutaneous benign tumors in all sea turtle species. Consequences of FP can range from mortality to complete tumor regression. Population-level impacts remain unclear due to lack of long-term data and the relatively recent emergence of FP in a group of extremely long-lived species. However, some turtles appear more susceptible to FP than others, and to date the green turtle Chelonia mydas shows significantly higher FP prevalence than all other species. CFPHV replicates in FP tumors and has been detected in every case of FP where tumors have been examined for the virus. However, no definitive causal relationship has been established between acquiring a CFPHV infection and developing FP, and there has been limited exploration of viral presence in non-tumor tissues. Here, we present quantitative data on CFPHV infection rates and infection loads in blood sampled from C. mydas individuals with FP compared to individuals without FP to assess whether there is a significant association between presence of the virus and presence of the tumors. Using blood samples collected year-round as part of a long-term, in-water study, we explore whether other turtle factors, including size, sampling date, and tumor severity, influence CFPHV dynamics. Answering these questions will enable us to pose more sophisticated questions about the role of CFPHV in sea turtle disease, including whether other pathogens or environmental factors may be driving the emergence of FP.