title: A Genomic Approach to Unravel Host-Pathogen Interaction in Chelonians: The Example of Testudinid Herpesvirus 3.
abstract: We report the first de novo sequence assembly and analysis of the genome of Testudinid herpesvirus 3 (TeHV3), one of the most pathogenic chelonian herpesviruses. The genome of TeHV3 is at least 150,080 nucleotides long, is arranged in a type D configuration and comprises at least 102 open reading frames extensively co-linear with those of Human herpesvirus 1. Consistently, the phylogenetic analysis positions TeHV3 among the Alphaherpesvirinae, closely associated with Chelonid herpesvirus 5, a Scutavirus. To date, there has been limited genetic characterization of TeHVs and a resolution beyond the genotype was not feasible because of the lack of informative DNA sequences. To exemplify the potential benefits of the novel genomic information provided by this first whole genome analysis, we selected the glycoprotein B (gB) gene, for detailed comparison among different TeHV3 isolates. The rationale for selecting gB is that it encodes for a well-conserved protein among herpesviruses but is coupled with a relevant antigenicity and is consequently prone to accumulate single nucleotide polymorphisms. These features were considered critical for an ideal phylogenetic marker to investigate the potential existence of distinct TeHV3 genogroups and their associated pathology. Fifteen captive tortoises presumptively diagnosed to be infected with TeHVs or carrying compatible lesions on the basis of either the presence of intranuclear inclusions (presumptively infected) and/or diphtheronecrotic stomatitis-glossitis or pneumonia (compatible lesions) were selected for the study. Viral isolation, TeHV identification, phylogenetic analysis and pathological characterization of the associated lesions, were performed. Our results revealed 1) the existence of at least two distinct TeHV3 genogroups apparently associated with different pathologies in tortoises and 2) the first evidence for a putative homologous recombination event having occurred in a chelonian herpesvirus. This novel information is not only fundamental for the genetic characterization of this virus but is also critical to lay the groundwork for an improved understanding of host-pathogen interactions in chelonians and contribute to tortoise conservation.
authors.affiliation: Centre for Fish and Wildlife Health (FIWI), Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Francesco C
authors.initials: FC
authors.lastname: Origgi
authors.affiliation: Department of veterinary sciences and public health (DIVET) Universita' degli studi di Milano, Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Tecilla
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Paola
authors.initials: P
authors.lastname: Pilo
authors.affiliation: IDEXX Laboratories Italia S.r.l., Milano, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Aloisio
authors.affiliation: Fasteris SA, Geneva, Switzerland.
authors.forename: Patricia
authors.initials: P
authors.lastname: Otten
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern Switzerland.
authors.forename: Lisandra
authors.initials: L
authors.lastname: Aguilar-Bultet
authors.affiliation: Centre for Fish and Wildlife Health (FIWI), Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Ursula
authors.initials: U
authors.lastname: Sattler
authors.affiliation: Department of veterinary sciences and public health (DIVET) Universita' degli studi di Milano, Milano, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Roccabianca
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Romero
authors.affiliation: Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: David C
authors.initials: DC
authors.lastname: Bloom
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Elliott R
authors.initials: ER
authors.lastname: Jacobson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D005260:Female; D016678:Genome / Q000235:genetics; D023281:Genomics / Q000379:methods*; D005838:Genotype; D005843:Geography; D006564:Herpesviridae / Q000145:classification / Q000235:genetics* / Q000502:physiology*; D054884:Host-Pathogen Interactions; D008297:Male; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013557:Switzerland; D020079:Terminal Repeat Sequences / Q000235:genetics; D014426:Turtles / Q000821:virology*; D014759:Viral Envelope Proteins / Q000235:genetics
chemical_list: D014759:Viral Envelope Proteins; D004259:DNA-Directed DNA Polymerase