First molecular detection and characterization of herpesvirus and poxvirus in a Pacific walrus (Odobenus rosmarus divergens)

Abstract

BackgroundHerpesvirus and poxvirus can infect a wide range of species: herpesvirus genetic material has been detected and amplified in five species of the superfamily Pinnipedia; poxvirus genetic material, in eight species of Pinnipedia. To date, however, genetic material of these viruses has not been detected in walrus (Odobenus rosmarus), another marine mammal of the Pinnipedia clade, even though anti-herpesvirus antibodies have been detected in these animals.Case presentationIn February 2013, a 9-year-old healthy captive female Pacific walrus died unexpectedly at L’Oceanografic (Valencia, Spain). Herpesvirus was detected in pharyngeal tonsil tissue by PCR. Phylogenetic analysis revealed that the virus belongs to the subfamily Gammaherpesvirinae. Poxvirus was also detected by PCR in skin, pre-scapular and tracheobronchial lymph nodes and tonsils. Gross lesions were not detected in any tissue, but histopathological analyses of pharyngeal tonsils and lymph nodes revealed remarkable lymphoid depletion and lymphocytolysis. Similar histopathological lesions have been previously described in bovine calves infected with an alphaherpesvirus, and in northern elephant seals infected with a gammaherpesvirus that is closely related to the herpesvirus found in this case. Intracytoplasmic eosinophilic inclusion bodies, consistent with poxviral infection, were also observed in the epithelium of the tonsilar mucosa.ConclusionTo our knowledge, this is the first molecular identification of herpesvirus and poxvirus in a walrus. Neither virus was likely to have contributed directly to the death of our animal.

First molecular determination of herpesvirus from two mysticete species stranded in the Mediterranean Sea

“…The novel herpesvirus DNApol sequences described here from fin whale and common minke whale were most closely related to DNApol sequences from other cetacean herpesviruses. This is consistent with previous observations that herpesvirus phylogenetic branching resembles that of its hosts [ 27 , 33 – 35 ].…”

“…Standard precautions were taken to prevent cross-contamination of samples. Negative controls for DNA extraction and PCR reactions were conducted in the absence of template and using a previously tested negative sample, while positive reactions were conducted using known herpesvirus DNA obtained from walrus [ 27 ].…”

Fatal pulmonary parafilaroidiasis in a free-ranging subantarctic fur seal (Arctocephalus tropicalis) coinfected with two gammaherpesviruses and Sarcocystis sp.

“…Two gammaherpesvirus sequences were detected, widening the host range of herpesvirus in pinnipeds. No intranuclear inclusion bodies were observed on histopathology, similarly to other reports of herpesvirus infections in pinnipeds (MELERO et al, 2014;SACRISTÁN et al, 2018). According to the International Committee on Taxonomy of Viruses for herpesviruses (DAVISON et al, 2005), the observed nucleotide and amino acid identities suggest the gammaherpesvirus sequence MH921584 could be classified as a novel species, proposed here as Otariid herpesvirus 7, while the other sequence (MH921583) was possibly a different OtHV-5 strain.…”

Cetacean Poxvirus in Two Striped Dolphins (Stenella coeruleoalba) Stranded on the Tyrrhenian Coast of Italy: Histopathological, Ultrastructural, Biomolecular, and Ecotoxicological Findings

“…Tattoo skin disease (TSD) is a poxviral cetacean disease. Poxviruses are large DNA viruses infecting humans and several domestic and wild animal species ( 1 , 2 ). Limited available sequencing of Cetacean Poxvirus (CePV) isolates places them in an unclassified genus within the Chordopoxvirinae subfamily, which includes at least two groups: Cetacean Poxvirus type 1 (CePV-1) in odontocetes and CePV-2 in mysticetes ( 3 ).…”