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Pestiviruses typically infect members of the order Artiodactyla, including ruminants and pigs, although putative rat and bat pestiviruses have also been described. In the present study, we identified and characterized an evolutionary divergent pestivirus in the toothed whale species, harbour porpoise (Phocoena phocoena). We tentatively named the virus Phocoena pestivirus (PhoPeV). PhoPeV displays a typical pestivirus genome organization except for the unique absence of Npro, an N-terminal autoprotease that targets the innate host immune response. Evolutionary evidence indicates that PhoPeV emerged following an interspecies transmission event from an ancestral pestivirus that expressed Npro. We show that 9% (n = 10) of stranded porpoises from the Dutch North Sea coast (n = 112) were positive for PhoPeV and they displayed a systemic infection reminiscent of non-cytopathogenic persistent pestivirus infection. The identification of PhoPeV extends the host range of pestiviruses to cetaceans (dolphins, whales, porpoises), which are considered to have evolved from artiodactyls (even-toed ungulates). Elucidation of the pathophysiology of PhoPeV infection and Npro unique absence will add to our understanding of molecular mechanisms governing pestivirus pathogenesis.

Herpesvirus infection causes disease of variable severity in many species, including cetaceans. However, little is known about herpesvirus infection in harbor porpoises (Phocoena phocoena), despite being widespread in temperate coastal waters of the Northern Hemisphere. Therefore, we examined harbor porpoises that stranded alive in the Netherlands, Belgium, and Germany between 2000 and 2014 for herpesvirus infection and associated disease. Porpoises that died or had to be euthanized were autopsied, and samples were collected for virological and pathological analyses. We found one known herpesvirus (Phocoena phocoena herpesvirus type 1, PPHV-1)—a gammaherpesvirus—and two novel herpesviruses (PPHV-2 and PPHV-3)—both alphaherpesviruses—in these porpoises. A genital plaque, in which PPHV-1 was detected, occurred in 1% (1/117) of porpoises. The plaque was characterized by epithelial hyperplasia and intranuclear inclusion bodies that contained herpesvirus-like particles, and that stained positive by a PPHV-1-specific in situ hybridization test. PPHV-2 occurred in the brain of 2% (1/74) of porpoises. This infection was associated with lymphocytic encephalitis, characterized by neuronal necrosis and intranuclear inclusion bodies containing herpesvirus-like particles. PPHV-3 had a prevalence of 5% (4/74) in brain tissue, 5% (2/43) in blowhole swabs, and 2% (1/43) in genital swabs, but was not associated with disease. Phylogenetically, PPHV-1 was identical to a previously reported herpesvirus from a harbor porpoise, PPHV-2 showed closest identity with two herpesviruses from dolphins, and PPHV-3 showed closest identity with a cervid herpesvirus. In conclusion, harbor porpoises may be infected with at least three different herpesviruses, one of which can cause clinically severe neurological disease.

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