Department of Infectious Diseases and Immunology, University of Florida, 2187 Mowry Road, 32611, Gainesville, FL, USA.
Department of Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB, R3T 2N6 Canada.
Virus Res. 2021 Jan 2;291:198187. doi: 10.1016/j.virusres.2020.198187. Epub 2020 Oct 16.
The family Togaviridae comprises several significant human and veterinary mosquito-borne pathogens. Two togaviruses (genus Alphavirus) have been previously identified in association with marine mammals, the southern elephant seal virus (SESV) and Eastern equine encephalitis virus (EEEV) from a fatal captive harbor seal infection. Herein we report the ultrastructural and phylogenomic characterization of a novel marine togavirus, the first isolated from a cetacean, an Alaskan harbor porpoise (Phocoena phocoena) displaying ulcerative dermatitis. A skin sample was processed for virus isolation on Vero.DogSLAMtag cells and cytopathic effects (CPE) were observed on primary isolation approximately 20 days post-infection. Transmission electron microscopy of the infected Vero.DogSLAMtag cells revealed typical alphavirus particles budding from both plasma and vacuolar membranes of infected cells. A next-generation sequencing approach was used to determine the near complete genome of the Alaskan harbor porpoise alphavirus (AHPV). Phylogenetic analysis supported the AHPV as the sister species to the SESV, forming a marine mammal alphavirus clade separate from the recognized alphavirus antigenic complexes. Genetic comparison of the protein coding sequence of the AHPV to other alphaviruses demonstrated amino acid identities ranging from 42.1-67.1%, with the highest identity to the SESV. Based on its genetic divergence, we propose the AHPV represents a novel alphavirus species, pending formal proposal to and ratification by the International Committee on Taxonomy of Viruses. The ecological and genetic characteristics of the AHPV and the SESV also suggest they represent a novel antigenic complex within the genus Alphavirus, which we propose to be named the Marine Mammal Virus Complex. The role of the AHPV in the associated harbor porpoise cutaneous pathology, if any, remains unclear. Further research is needed to determine AHPV's route(s) of transmission and potential vectors, host range, prevalence, and pathogenicity in cetaceans including harbour porpoises.
披膜病毒科包含几种重要的人兽共患蚊媒病原体。先前已在海洋哺乳动物中发现了两种披膜病毒（属甲病毒），即与致命圈养海豹感染有关的南部象海豹病毒（SESV）和东部马脑炎病毒（EEEV）。在此，我们报告了一种新型海洋披膜病毒的超微结构和系统基因组特征，这是从一种海洋哺乳动物，即表现出溃疡性皮炎的阿拉斯加港湾海豚中分离到的第一种甲病毒。对显示溃疡性皮炎的阿拉斯加港湾海豚的皮肤样本进行病毒分离处理，在原代分离后约 20 天观察到细胞病变效应（CPE）。感染的 Vero.DogSLAMtag 细胞的透射电子显微镜显示，典型的甲病毒颗粒从感染细胞的质膜和液泡膜上出芽。使用下一代测序方法确定了阿拉斯加港湾海豚甲病毒（AHPV）的近全长基因组。系统进化分析支持 AHPV 是 SESV 的姐妹种，形成一个与已识别的甲病毒抗原复合物分开的海洋哺乳动物甲病毒群。AHPV 的蛋白编码序列与其他甲病毒的遗传比较表明，氨基酸同一性范围为 42.1-67.1%，与 SESV 的同一性最高。基于其遗传差异，我们建议 AHPV 代表一种新型甲病毒种，等待国际病毒分类学委员会的正式提议和批准。AHPV 和 SESV 的生态和遗传特征也表明它们代表了属甲病毒中的一个新的抗原复合物，我们建议将其命名为海洋哺乳动物病毒复合物。AHPV 在相关港湾海豚皮肤病理学中的作用（如果有的话）尚不清楚。需要进一步研究以确定 AHPV 在鲸目动物（包括港湾海豚）中的传播途径和潜在载体、宿主范围、流行率和致病性。
