DataSheet_2_Tracing the invertebrate herpesviruses in the global sequence datasets.zip

The family of Malacoherpesviridae is currently represented by only two viruses infecting molluscs, Ostreid herpesvirus 1 (OsHV-1) and Haliotid herpesvirus 1 (HaHV-1), both causing detrimental infections in aquaculture species. Malacoherpesvirus-like sequences were also detected through genome sequencing projects in amphioxus (Branchiostoma species) and annelid worm (Capitella teleta), suggesting the existence of a hidden diversity of malacoherpesviruses in aquatic animals. Here, to extend the knowledge on malacoherpesvirus diversity, we searched for the presence of malacoherpesvirus relatives in genomic, transcriptomic and metagenomic datasets, including from the Tara Oceans expedition, and report 4 novel malacoherpesvirus-like genomes (MalacoHV1-4). Genomic analysis suggested gastropods and bivalves as the most probable hosts for these new malacoherpesviruses. Phylogenetic analysis based on the family B DNA polymerase placed the novel MalacoHV1 and MalacoHV3 as sister lineages of OsHV-1 and HaHV-1, respectively, whereas MalacoHV2 and MalacoHV4 showed higher divergence. The viral genome found associated with amphioxus together with MalacoHV4 formed a sister clade to the mollusc and annelid malacoherpesviruses, suggesting an early divergence of the two virus assemblages. In conclusion, although relatively rare in the available sequence databases, the previously undescribed malacoherpesviruses, MalacoHV1-4, circulate in aquatic ecosystems and should be considered as possible emerging viruses under changing environmental conditions.软壳疱疹病毒科（Malacoherpesviridae）目前仅包含2种感染软体动物的病毒：牡蛎疱疹病毒1型（Ostreid herpesvirus 1, OsHV-1）与鲍疱疹病毒1型（Haliotid herpesvirus 1, HaHV-1），二者均可对水产养殖物种造成致病性感染。研究人员还通过基因组测序项目，在文昌鱼（Branchiostoma属物种）和环节动物小头虫（Capitella teleta）中检测到类软壳疱疹病毒序列，这提示水生动物中存在未被发掘的软壳疱疹病毒多样性。为拓展对软壳疱疹病毒多样性的认知，本研究对涵盖塔拉海洋科考航次（Tara Oceans expedition）数据集在内的基因组、转录组及宏基因组数据开展类软壳疱疹病毒亲缘关系检索，最终报道了4个新型类软壳疱疹病毒基因组（MalacoHV1-4）。基因组分析结果显示，腹足类与双壳类可能是这4种新型软壳疱疹病毒的最主要宿主。基于B家族DNA聚合酶（family B DNA polymerase）的系统发育分析显示：新型病毒MalacoHV1与MalacoHV3分别为OsHV-1和HaHV-1的姊妹演化支，而MalacoHV2与MalacoHV4的演化分歧程度更高。与文昌鱼相关的病毒基因组与MalacoHV4共同构成了软体动物及环节动物软壳疱疹病毒的姊妹演化支，提示两类病毒群存在早期演化分化。综上，尽管现有序列数据库中软壳疱疹病毒相对稀有，但本次新发现的MalacoHV1-4这4种此前未被报道的软壳疱疹病毒可在水生生态系统中循环传播，在环境变化的背景下，应将其视为潜在的新发病毒。