High‐throughput isolation of giant viruses of the M imiviridae and M arseilleviridae families in the T unisian environment

Abstract

Summary Giant viruses of the M egavirales order have been recently isolated from aquatic environments and have long been neglected because they are removed from samples during viral purification for viral metagenomic studies. Due to bacterial overgrowth and susceptibility to high concentrations of antibiotics, isolation by amoeba co‐culture has a low efficiency and is highly time‐consuming. Thus, few environments have been exhaustively investigated to date, although the ubiquitous distribution of the A canthamoeba sp. suggests that these viruses could also be ubiquitous. In this work, we have implemented a high‐throughput method to detect amoebae lysis on agar plates that allows the testing of hundreds of samples in a few days. Using this procedure, a total of 11 new M arseilleviridae strains and four new M imiviridae strains, including a virus infected with a virophage, were isolated from 1000 environmental samples from T unisia. Of these, four corresponded to new genotypic variants. These isolates are the first A frican environmental isolates identified from these two families, and several samples were obtained from a hypersaline aquatic environment. These results demonstrate that this technique can be used for the evaluation and characterization of large collections of giant viruses to provide insight into understanding their ecology.

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