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.

一只出生在水族馆并在日本人工饲养的海象（Odobenus rosmarus）在11个月大时死亡。受影响的动物表现出发烧和厌食症，并且具有高水平的 AST 和 ALT。尸检显示肝脏和肾上腺多发坏死，组织学检查显示肝脏和肾上腺皮质有坏死病变，两者均含有核内包涵体。肝脏样本的电子显微镜分析显示疱疹病毒样颗粒。肝脏样本的高通量测序分析和疱疹病毒聚合酶基因的系统发育分析确定了一种新病毒，海象α疱疹病毒 1 (WaHV-1)，属于Alphaherpesvirinae亚科并且与 Phocid alphaherpesvirus 1 具有高度同源性。对编码糖蛋白 B 的 UL30 基因的系统发育分析表明，WaHV-1 与一组 phocid 疱疹病毒密切相关，其中包括一种在过去爆发期间导致斑海豹高死亡率的病毒。这头死动物的母亲海象过去曾有疱疹病毒感染的迹象，并可能携带 WaHV-1。由于人工饲养，死动物可能从其受感染的母亲那里获得了 WaHV-1，并由于缺乏母体 IgG（包括那些可以中和 WaHV-1 的 IgG）而死于 WaHV-1。