Molecular analysis of PAV1, the first marine hyperthermophilic virus : Screening and preliminary characterization of virus-like particles infecting archaea from the order Thermococcales in deep-sea vents

PAV1, discovered in our lab, is the first hyperthermophilic virus isolated from a deep-sea vent. It is lemon-shaped and infects the archea Pyroccoccus abyssi. Its genome is a double stranded DNA of 18. 1 kbp. Here we report the molecular analysis of this virus. First, we studied PAV1 genome. We proved it is high copy number (about 70 copies per chromosome) and slightly negatively supercoiled in its host. As the archeal chromosome, viral DNA is not dam or dcm methylated. All 25 predicted genes are transcribed in six mRNAs in majority polycistronic and the larger one covers 75 % of genome. Then, we tried to show that protein 899 could be involved in viral DNA metabolism and we identified protein 121 as one of the majority protein. The last part of this study aimed to discover new viruses infecting archaea from the order Thermococcales in deep-sea environment. Observations realized with transmission electronic microscope on enrichment cultures revealed an unexpected viral diversity. Then, a screening was realized one about 120 Thermococcales strains and we discovered a piezophilic strain named KAZA from specie Thermococcus barophilus which produces “piezo-dependanr” virus-like particles.