Crocodilepox Virus Evolutionary Genomics Supports Observed Poxvirus Infection Dynamics on Saltwater Crocodile (Crocodylus porosus)
journal contributionposted on 2020-11-08, 23:34 authored by Subir Sarker, SR Isberg, JL Moran, RD Araujo, N Elliott, L Melville, Travis Beddoe, Karla J Helbig
© 2019 by the authors. Saltwater crocodilepox virus (SwCRV), belonging to the genus Crocodylidpoxvirus, are large DNA viruses posing an economic risk to Australian saltwater crocodile (Crocodylus porosus) farms by extending production times. Although poxvirus-like particles and sequences have been confirmed, their infection dynamics, inter-farm genetic variability and evolutionary relationships remain largely unknown. In this study, a poxvirus infection dynamics study was conducted on two C. porosus farms. One farm (Farm 2) showed twice the infection rate, and more concerningly, an increase in the number of early- to late-stage poxvirus lesions as crocodiles approached harvest size, reflecting the extended production periods observed on this farm. To determine if there was a genetic basis for this difference, 14 complete SwCRV genomes were isolated from lesions sourced from five Australian farms. They encompassed all the conserved genes when compared to the two previously reported SwCRV genomes and fell within three major clades. Farm 2's SwCRV sequences were distributed across all three clades, highlighting the likely mode of inter-farm transmission. Twenty-four recombination events were detected, with one recombination event resulting in consistent fragmentation of the P4c gene in the majority of the Farm 2 SwCRV isolates. Further investigation into the evolution of poxvirus infection in farmed crocodiles may offer valuable insights in evolution of this viral family and afford the opportunity to obtain crucial information into natural viral selection processes in an in vivo setting.
The authors are grateful to the La Trobe University Securing Food, Water, and Environment, RFA, ABC Research Funding Scheme 2017, and the Centre for Crocodile Research, Noonamah, Australia for funding this research (Project ID: 0001027183). This study was partially funded by AgriFutures Australia (PRJ-010453) and the crocodile farms.
La Trobe University Securing Food, Water, and Environment, RFA, ABC Research Funding Scheme 2017
Centre for Crocodile Research, Noonamah, Australia | 0001027183
AgriFutures Australia | PRJ-010453
Article NumberARTN 1116
PublisherMultidisciplinary Digital Publishing Institute (MDPI)
Rights StatementThe Author reserves all moral rights over the deposited text and must be credited if any re-use occurs.
Science & TechnologyLife Sciences & BiomedicineVirologysaltwater crocodilepox virusinfection dynamicscomplete genomeevolutiongenetic recombinationMOSAIC STRUCTURERECOMBINATIONSEQUENCEIDENTIFICATIONPERFORMANCEIMPACTGENEAnimalsAlligators and CrocodilesChordopoxvirinaePoxviridae InfectionsAnimal DiseasesPrevalenceGenomicsEvolution, MolecularPhylogenyRecombination, GeneticAmino Acid SequenceGenome, ViralAustralia