Abstract: Virophages are small double-stranded DNA viruses that parasitize giant viruses of protists. With the co-existence of viroph-ages, giant viruses decrease the infection of single-cell eukaryotic hosts, resulting in increased survival rates of eukaryotic hosts. Vir-ophage were firstly isolated from the co-culture system of giant viruses and eukaryotic hosts. Subsequently, metagenomic analysisshowed that they widely distributed in the global aquatic environments, especially in fresh water habitats. Here complete genomic se-quences of three novel virophages (Global Ocean Viromes Virophage_1 /2/3, GOV_V1 /2/3) were identified through in-depth analysis of the Global Ocean Viromes datasets. Phylogenetic and genomic analyses indicated that GOV_V1 is most closely related to potential al-gae virus-infecting virophages (such as QLV and YSLV1,4,6), and GOV2_V2 /3 are mostly related to amoeba-infecting virophages (Sputnikvirus). These findings indicated that microalgae may be the hosts of GOV2_V1, while protozoan may be the hosts of GOV2_ V2 / 3.

Key words: virophage, global ocean viromes, metavirome