The Ozobranchus leech is a candidate mechanical vector for the fibropapilloma-associated turtle herpesvirus found latently infecting skin tumors on Hawaiian green turtles (Chelonia mydas)

Abstract

Fibropapillomatosis (FP) of marine turtles is a neoplastic disease of ecological concern. A fibropapilloma-associated turtle herpesvirus (FPTHV) is consistently present, usually at loads exceeding one virus copy per tumor cell. DNA from an array of parasites of green turtles (Chelonia mydas) was examined with quantitative PCR (qPCR) to determine whether any carried viral loads are sufficient to implicate them as vectors for FPTHV. Marine leeches (Ozobranchus spp.) were found to carry high viral DNA loads; some samples approached 10 million copies per leech. Isopycnic sucrose density gradient/qPCR analysis confirmed that some of these copies were associated with particles of the density of enveloped viruses. The data implicate the marine leech Ozobranchus as a mechanical vector for FPTHV. Quantitative RT-PCR analysis of FPTHV gene expression indicated that most of the FPTHV copies in a fibropapilloma have restricted DNA polymerase expression, suggestive of latent infection.

Genomic Variation of the Fibropapilloma-Associated Marine Turtle Herpesvirus across Seven Geographic Areas and Three Host Species

“…Waterborne infection would be expected to be more efficient in embayments where turtles congregate than in the open ocean. Similarly, the coastal organism Ozobranchus, a marine leech that parasitizes turtles, has recently been shown to harbor FPTHV DNA associated with particles of the density of enveloped viruses; this leech thus may act as a vector for FPTHV (10).…”

“…The magnitudes of these loads indicate that viral gene products could be present in sufficient quantities to serve as driving forces for tumor development and/or maintenance. Viral polymerase gene expression has not been detected in fibropapillomas or fibromas, suggesting that infection is predominantly latent in tumors, comparable to human herpesvirus 8 in Kaposi's sarcoma lesions or gallid herpesvirus 2 in the tumors associated with Marek's disease of chickens (10,32,33,36). This putative disease agent has been called the green turtle herpesvirus or the FPTHV.…”

Detection and characterization of fibropapilloma associated herpesvirus of marine turtles in Rio Grande do Sul, Brazil

“…A herpesvirus has been identiϐied in 100% of tumors induced by inoculation of tumor cell inϐiltrates (Ene et al 2005) and 95% of natural infections (Quackenbush et al 2001). However, the disease seems have a multifactor character, since the presence of ectoparasites (Greenblatt et al 2004), environmental pollution , Santos et al 2010, ingestion of macroalgae (Van Houtan et al 2010) as well as water temperature (Herbst et al 1995) seem to inϐluence FP occurrence. The herpesvirus detected in ϐibropapillomas belongs to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Scutavirus, and was called chelonid herpesvirus 5 (ChHV-5) (ICTV, 2011).…”

First histological and virological report of fibropapilloma associated with herpesvirus in Chelonia mydas at Príncipe Island, West Africa

“…undetermined, the involvement of herpesvirus, pollutants, metazoan parasites [10,11], marine toxins, ultraviolet light [8] and rising temperature [12] has been suggested. However, the detection of chelonid fibropapilloma-associated herpesvirus (CFPHV) genomic DNA is a constant factor in afflicted animals [13,14], and viral DNA can also be present in the skin of asymptomatic animals [15].…”