The Concurrent Detection of Chelonid Alphaherpesvirus 5 and Chelonia mydas Papillomavirus 1 in Tumoured and Non-Tumoured Green Turtles

Characterised by the growth of benign tumours, fibropapillomatosis (FP) is a debilitating disease that predominantly afflicts the endangered green turtle (Chelonia mydas). A growing body of histological and molecular evidence has consistently associated FP tumours with Chelonid alphaherpesvirus 5 (ChHV5), leading this virus to be considered the most likely aetiological agent of FP. However, a recent study which detected both ChHV5 and Chelonia mydas papillomavirus 1 (CmPV1) DNA in FP tumour tissues has challenged this hypothesis. The present study aimed to establish the wider prevalence of CmPV1 and co-occurrence with ChHV5 in marine turtles in waters adjacent to the east coast of Queensland, Australia. This comprehensive molecular survey screened a total of 353 samples from 275 foraging turtles using probe-based qPCR. Three sample categories were used in this study: Group A (FP tumours), Group B (non-tumoured skin from turtles with FP tumours) and Group C (non-tumoured skin from turtles without FP tumours). Concurrent detection of ChHV5 and CmPV1 DNA is reported for all three categories, with the highest rate of concurrent detection reported for Group A samples (43.5%). Collectively, these results pivot the way we think about FP; as an infectious disease where two separate viruses may be at play.