title: Global distribution of Chelonid fibropapilloma-associated herpesvirus among clinically healthy sea turtles.
abstract: BACKGROUND
  Fibropapillomatosis (FP) is a neoplastic disease characterized by cutaneous tumours that has been documented to infect all sea turtle species. Chelonid fibropapilloma-associated herpesvirus (CFPHV) is believed to be the aetiological agent of FP, based principally on consistent PCR-based detection of herpesvirus DNA sequences from FP tumours. We used a recently described PCR-based assay that targets 3 conserved CFPHV genes, to survey 208 green turtles (Chelonia mydas). This included both FP tumour exhibiting and clinically healthy individuals. An additional 129 globally distributed clinically healthy individual sea turtles; representing four other species were also screened.
  
  
  RESULTS
  CFPHV DNA sequences were obtained from 37/37 (100%) FP exhibiting green turtles, and 45/300 (15%) clinically healthy animals spanning all five species. Although the frequency of infected individuals per turtle population varied considerably, most global populations contained at least one CFPHV positive individual, with the exception of various turtle species from the Arabian Gulf, Northern Indian Ocean and Puerto Rico. Haplotype analysis of the different gene markers clustered the CFPHV DNA sequences for two of the markers (UL18 and UL22) in turtles from Turks and Caicos separate to all others, regardless of host species or geographic origin.
  
  
  CONCLUSIONS
  Presence of CFPHV DNA within globally distributed samples for all five species of sea turtle was confirmed. While 100% of the FP exhibiting green turtles yielded CFPHV sequences, surprisingly, so did 15% of the clinically healthy turtles. We hypothesize that turtle populations with zero (0%) CFPHV frequency may be attributed to possible environmental differences, diet and/or genetic resistance in these individuals. Our results provide first data on the prevalence of CFPHV among seemingly healthy turtles; a factor that may not be directly correlated to the disease incidence, but may suggest of a long-term co-evolutionary latent infection interaction between CFPHV and its turtle-host across species. Finally, computational analysis of amino acid variants within the Turks and Caicos samples suggest potential functional importance in a substitution for marker UL18 that encodes the major capsid protein gene, which potentially could explain differences in pathogenicity. Nevertheless, such a theory remains to be validated by further research.
authors.affiliation: Centre for GeoGenetics, Section for Evolutionary Genomics, Natural History Museum of Denmark, Øster Voldgade 5-7, 1350, Copenhagen K, Denmark. alonzoalfaro@gmail.com.
authors.forename: Alonzo
authors.initials: A
authors.lastname: Alfaro-Núñez
authors.affiliation: Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark. mfb@zoo.dk.
authors.forename: Mads
authors.initials: M
authors.lastname: Frost Bertelsen
authors.affiliation: Department of Veterinary Disease Biology, Veterinary Clinical Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. miki@sund.ku.dk.
authors.forename: Anders Miki
authors.initials: AM
authors.lastname: Bojesen
authors.affiliation: Centre for GeoGenetics, Section for Evolutionary Genomics, Natural History Museum of Denmark, Øster Voldgade 5-7, 1350, Copenhagen K, Denmark. isabelhojgaard@gmail.com.
authors.forename: Isabel
authors.initials: I
authors.lastname: Rasmussen
authors.affiliation: Centre for GeoGenetics, Section for Evolutionary Genomics, Natural History Museum of Denmark, Øster Voldgade 5-7, 1350, Copenhagen K, Denmark. lisandracady@gmail.com.
authors.forename: Lisandra
authors.initials: L
authors.lastname: Zepeda-Mendoza
authors.affiliation: Centre for GeoGenetics, Section for Evolutionary Genomics, Natural History Museum of Denmark, Øster Voldgade 5-7, 1350, Copenhagen K, Denmark. mortentolsen@gmail.com.
authors.forename: Morten
authors.initials: M
authors.lastname: Tange Olsen
authors.affiliation: Centre for GeoGenetics, Section for Evolutionary Genomics, Natural History Museum of Denmark, Øster Voldgade 5-7, 1350, Copenhagen K, Denmark. mtpgilbert@gmail.com.|Trace and Environmental DNA Laboratory, School of Environment and Agriculture, Curtin University, Perth, Western Australia, 6845, Australia. mtpgilbert@gmail.com.
authors.forename: Marcus Thomas Pius
authors.initials: MT
authors.lastname: Gilbert
mesh_terms: D000818:Animals; D006564:Herpesviridae / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D009154:Mutation; D015995:Prevalence; D012878:Skin Neoplasms / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D014426:Turtles / Q000145:classification / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics; D017735:Virus Latency
chemical_list: D014764:Viral Proteins