Novel herpesvirus discovered in walrus liver

Sumiya Borjigin, Nanako Osawa, Kaixin Li, Yukie Katayama, Yoshio Kawamura, Makoto Haritani, Shinji Makino, Testuya Mizutani, Mami Oba

Research output: Contribution to journalArticlepeer-review


A walrus (Odobenus rosmarus) born in an aquarium and hand-reared in Japan died at the age of 11 months. The affected animal showed fever and anorexia and had high levels of AST and ALT. Necropsy showed multiple necroses in the liver and adrenal glands and histological examination revealed necrotic lesions of the liver and adrenal cortex, both of which contained intranuclear inclusions. Electron microscopic analysis of the liver sample showed herpesvirus-like particles. High-throughput sequencing analysis of the liver sample and phylogenetic analysis of herpesvirus polymerase genes identified a new virus, Walrus alphaherpesvirus 1 (WaHV-1), which belonged to the subfamily Alphaherpesvirinae and had high homology with Phocid alphaherpesvirus 1. Phylogenetic analysis of the UL30 gene encoding glycoprotein B revealed that WaHV-1 was closely related to a cluster of phocid herpesviruses, including one that caused high mortality rates in harbor seals during past outbreaks. The mother walrus of the dead animal showed evidence of herpesvirus infection in the past and potentially harbored WaHV-1. As a result of hand-rearing, the dead animal might have acquired WaHV-1 from its infected mother and succumbed to WaHV-1 due to lack of maternal IgG, including those that could neutralize WaHV-1.

Original languageEnglish (US)
Pages (from-to)228-232
Number of pages5
JournalVirus Genes
Issue number2
StatePublished - Apr 2021


  • Alphaherpesvirus
  • Aquarium
  • High-throughput sequencing
  • Japan
  • Walrus

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Virology


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