Driving forces behind the evolution of the Aleutian mink disease parvovirus in the context of intensive farming

Marta Canuti; Kimberly E O'Leary; Bruce D Hunter; Grant Spearman; Davor Ojkic; Hugh G Whitney; Andrew S Lang

doi:10.1093/ve/vew004

Driving forces behind the evolution of the Aleutian mink disease parvovirus in the context of intensive farming

Virus Evol. 2016 Feb 27;2(1):vew004. doi: 10.1093/ve/vew004. eCollection 2016 Jan.

Authors

Marta Canuti¹, Kimberly E O'Leary², Bruce D Hunter³, Grant Spearman⁴, Davor Ojkic⁵, Hugh G Whitney², Andrew S Lang¹

Affiliations

¹ Department of Biology, Memorial University of Newfoundland, 232 Elizabeth Ave., St. John's, Newfoundland and Labrador, A1B 3X9, Canada.
² Animal Health Division, Forestry and Agrifoods Agency, P.O. Box 7400, St. John's, Newfoundland and Labrador, A1E 3Y5, Canada.
³ Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
⁴ Department of Agriculture, Animal Health Laboratory, 65 River Rd., Truro, Nova Scotia, B2N 5E3, Canada and.
⁵ Animal Health Laboratory, 419 Gordon Street, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.

Abstract

Aleutian mink disease virus (AMDV) causes plasmacytosis, an immune complex-associated syndrome that affects wild and farmed mink. The virus can also infect other small mammals (e.g., ferrets, skunks, ermines, and raccoons), but the disease in these hosts has been studied less. In 2007, a mink plasmacytosis outbreak began on the Island of Newfoundland, and the virus has been endemic in farms since then. In this study, we evaluated the molecular epidemiology of AMDV in farmed and wild animals of Newfoundland since before the beginning of the outbreak and investigated the epidemic in a global context by studying AMDV worldwide, thereby examining its diffusion and phylogeography. Furthermore, AMDV evolution was examined in the context of intensive farming, where host population dynamics strongly influence viral evolution. Partial NS1 sequences and several complete genomes were obtained from Newfoundland viruses and analyzed along with numerous sequences from other locations worldwide that were either obtained as part of this study or from public databases. We observed very high viral diversity within Newfoundland and within single farms, where high rates of co-infection, recombinant viruses and polymorphisms were observed within single infected individuals. Worldwide, we documented a partial geographic distribution of strains, where viruses from different countries co-exist within clades but form country-specific subclades. Finally, we observed the occurrence of recombination and the predominance of negative selection pressure on AMDV proteins. A surprisingly low number of immunoepitopic sites were under diversifying pressure, possibly because AMDV gains no benefit by escaping the immune response as viral entry into target cells is mediated through interactions with antibodies, which therefore contribute to cell infection. In conclusion, the high prevalence of AMDV in farms facilitates the establishment of co-infections that can favor the occurrence of recombination and enhance viral diversity. Viruses are then exchanged between different farms and countries and can be introduced into the wild, with the rapidly evolving viruses producing many parallel lineages.

Keywords: AMDV; Aleutian mink disease virus; amdoparvoviruses; parvoviruses; viral evolution; viral recombination.