Jacob Jessica M, Subramaniam Kuttichantran, Tu Shin-Lin, Nielsen Ole, Tuomi Pamela A, Upton Chris, Waltzek Thomas B
Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32610, USA.
Biochemistry and Microbiology Department, University of Victoria, Victoria, BC, V8W 2Y2, Canada.
Virus Genes. 2018 Dec;54(6):756-767. doi: 10.1007/s11262-018-1594-8. Epub 2018 Sep 17.
Members of the Poxviridae family are large, double-stranded DNA viruses that replicate in the cytoplasm of their host cells. The subfamily Chordopoxvirinae contains viruses that infect a wide range of vertebrates including marine mammals within the Balaenidae, Delphinidae, Mustelidae, Odobenidae, Otariidae, Phocidae, and Phocoenidae families. Recently, a novel poxvirus was found in a northern sea otter pup (Enhydra lutris kenyoni) that stranded in Alaska in 2009. The phylogenetic relationships of marine mammal poxviruses are not well established because of the lack of complete genome sequences. The current study sequenced the entire sea otterpox virus Enhydra lutris kenyoni (SOPV-ELK) genome using an Illumina MiSeq sequencer. The SOPV-ELK genome is the smallest poxvirus genome known at 127,879 bp, is 68.7% A+T content, is predicted to encode 132 proteins, and has 2546 bp inverted terminal repeats at each end. Genetic and phylogenetic analyses based on the concatenated amino acid sequences of 7 chorodopoxvirus core genes revealed the SOPV-ELK is 52.5-74.1% divergent from other known chordopoxviruses and is most similar to pteropoxvirus from Australia (PTPV-Aus). SOPV-ELK represents a new chordopoxvirus species and may belong to a novel genus. SOPV-ELK encodes eight unique genes. While the function of six predicted genes remains unknown, two genes appear to function as novel immune-modulators. SOPV-ELK-003 appears to encode a novel interleukin-18 binding protein (IL-18 BP), based on limited sequence and structural similarity to other poxviral IL-18 BPs. SOPV-ELK-035 appears to encode a novel tumor necrosis factor receptor-like (TNFR) protein that may be associated with the depression of the host's antiviral response. Additionally, SOPV-ELK-036 encodes a tumor necrosis factor-like apoptosis-inducing ligand (TRAIL) protein that has previously only been found in PTPV-Aus. The SOPV-ELK genome is the first mustelid poxvirus and only the second poxvirus from a marine mammal to be fully sequenced. Sequencing of the SOPV-ELK genome is an important step in unraveling the position of marine mammal poxviruses within the larger Poxviridae phylogenetic tree and provides the necessary sequence to develop molecular tools for future diagnostics and epidemiological studies.
痘病毒科成员是大型双链DNA病毒，在宿主细胞的细胞质中进行复制。脊索痘病毒亚科包含可感染多种脊椎动物的病毒，这些脊椎动物包括须鲸科、海豚科、鼬科、海象科、海狮科、海豹科和鼠海豚科中的海洋哺乳动物。最近，在2009年搁浅于阿拉斯加的一只北海獭幼崽（Enhydra lutris kenyoni）中发现了一种新型痘病毒。由于缺乏完整的基因组序列，海洋哺乳动物痘病毒的系统发育关系尚未完全明确。本研究使用Illumina MiSeq测序仪对海獭痘病毒Enhydra lutris kenyoni（SOPV - ELK）的全基因组进行了测序。SOPV - ELK基因组是已知最小的痘病毒基因组，大小为127,879 bp，A + T含量为68.7%，预计编码132种蛋白质，两端各有2546 bp的反向末端重复序列。基于7种脊索痘病毒核心基因的串联氨基酸序列进行的遗传和系统发育分析表明，SOPV - ELK与其他已知脊索痘病毒的差异为52.5 - 74.1%，与来自澳大利亚的翼手痘病毒（PTPV - Aus）最为相似。SOPV - ELK代表一种新的脊索痘病毒物种，可能属于一个新的属。SOPV - ELK编码8个独特基因。虽然6个预测基因的功能尚不清楚，但有两个基因似乎起着新型免疫调节剂的作用。基于与其他痘病毒白细胞介素-18结合蛋白（IL - 18 BP）有限的序列和结构相似性，SOPV - ELK - 003似乎编码一种新型白细胞介素-18结合蛋白。SOPV - ELK - 035似乎编码一种新型肿瘤坏死因子受体样（TNFR）蛋白，可能与宿主抗病毒反应的抑制有关。此外，SOPV - ELK - 036编码一种肿瘤坏死因子样凋亡诱导配体（TRAIL）蛋白，该蛋白此前仅在PTPV - Aus中发现。SOPV - ELK基因组是首个鼬科痘病毒基因组，也是第二个完成全序列测定的海洋哺乳动物痘病毒基因组。对SOPV - ELK基因组进行测序是阐明海洋哺乳动物痘病毒在更大的痘病毒科系统发育树中位置的重要一步，并且为未来的诊断和流行病学研究开发分子工具提供了必要的序列。
