Two new bacilladnaviruses associated with the diatom Haslea ostrearia

Abstract

ABSTRACT Haslea ostrearia (Gaillon) Simonsen is famous among diatoms for producing a blue pigment. Genome sequencing of different strains of H. ostrearia led to the discovery of the complete genomes of two new bacilladnaviruses, HOV-148 and HOV-235. The DNA sequences of these viruses were identified in H. ostrearia strains that had been maintained for several years in a culture collection. Some of these strains are the products of in vitro episodes of auxosporulation and thus have never been in contact with their natural biotope. At 4567 and 4538 bp, the HOV-148 and HOV-235 genomes are shorter than those of most diatom-infecting viruses known to date. They each contain four open reading frames and display highest similarities with sequences from viruses found in a gastropod from New Zealand, a proximity confirmed by phylogenetic analysis. HOV-148 and HOV-235 were identified in three clones of H. ostrearia that were collected in oyster ponds from distinct locations in the Bay of Bourgneuf (France). Given that our search for similar viral sequences in genomic data derived from other sub-populations or species of the genus Haslea throughout the world was unsuccessful, we hypothesize that these viruses could have a link with the peculiar biotope of the oyster ponds.