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

Abstract

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.

Detection and population genomics of sea turtle species via noninvasive environmental DNA analysis of nesting beach sand tracks and oceanic water

“…The qPCR reaction mixtures were performed in a total volume of 10 µl: 5 µl TaqMan Fast Advanced Master Mix (Fisher Scientific cat no: 4444557); 3 µl Nuclease free water (Fisher Scientific); 1 µl ChHV5 DPol. (Mashkour et al, 2021) or custom C . mydas 16S rRNA or custom C .…”

Evolutionary Genomic Comparisons of Chelonid Herpesvirus 5 (chhv5) From Fibropapillomatosis-Afflicted Green (Chelonia Mydas), Olive Ridley (Lepidochelys Olivacea), And Kemp’s Ridley (Lepidochelys Kempii) Sea Turtles.

“…Fibropapillomatosis is one of the most significant transmissible diseases known in marine turtles and remains a persistent health concern despite conservation successes and significant growth of some affected populations [17]. The FP epizootic has been identified as one of the five major threats to marine turtles, which has been reflected in the renewed scientific interest in this disease in the last decade [5,7,11,13,[18][19][20][21][22][23][24][25][26]. Prevalence statistics reveal the rapid establishment of FP among many sea turtle populations; with reported increases from 13.3 to 42% in Florida, USA (2005-2016), 13.2 to 35.3% in northeastern Brazil (2012)(2013)(2014)(2015), 0% to 33% in Guinea-Bissau and 0 to 35.2% in Texas, USA [7,17,[27][28][29][30][31].…”

“…Molecular studies have consistently detected ChHV5 presence in turtles with FP, however, FP may also be found in turtles where ChHV5 is not detected [26,39], and ChHV5 is detectable in turtles without FP [40,41]. Recently, a strain of papillomavirus, PV1, was detected in 47% of FP tumours analysed, despite earlier conventional PCR-based approaches and whole genome sequencing failing to detect PV1 [25,26]. This suggests that other oncogenic viruses may contribute to the development of FP.…”