The project
The MEFISTO proposal aims to apply recent methodologies using specific viral staining and genomic and metagenomic analysis to study specific virus-host interactions. Thus, viral tagging by fluorescent staining with a vital dye (ViralTag) and the hybridization of viral genes with fluorescent probes (PhageFISH) will permit to detect the microbial cells infected with a specific virus. PhageFISH can also identify free phages, their replication and encapsidation, and recognize and quantify the host cells during all stages of infection. In addition, genomic and metagenomic analyses are useful for the detection of specific viral genes in bacterial and eukaryotic genomes and in metagenomes of the microbial community. This is based in the detection of viral genes in cultured virus-host models and, in the case of uncultured microbial diversity, in the development of a method to obtain the genomes of single cells isolated directly from the environment (single amplified genomes, SAGs). This is a promising approach for groups in which most members remain uncultured, such as the heterotrophic picoflagellates.The MEFISTO project is structured in two parts:
1) To develop two specific staining techniques to be implemented in cultured virus-host models. These techniques will be applied to phage-bacteria models (ViralTag and PhageFISH) and to virus-picoeukaryote models (ViralTag), both in the laboratory and then in the environment to analyze the viral impact in a seasonal cycle. We will use specific cultivated and sequenced viruses and their hosts isolated from Blanes Bay and Banyuls-sur-Mer, known to be representative of the study system, and maintained in culture at the ICM and OOB. Furthermore, from the sequenced viral genomes, specific genes will be selected to detect them in metagenomes generated in circumnavigation cruises (TaraOceans and Malaspina).
2) Identification of specific genes of viruses infecting uncultured picoeukaryotes by studying its genome sequenced from the SAGs. Once detected, the presence of these specific viruses will be investigated in metagenomes generated in Malaspina and TaraOceans cruises. This approach will allow estimating the impact of viral infection on the major phylogenetic lineages encompassing the functional group of heterotrophic picoflagellates.
