Marine Oomycetes of the Genus Halophytophthora Harbor Viruses Related to Bunyaviruses

Abstract

We investigated the incidence of RNA viruses in a collection of <i>Halophytophthora</i> spp. from estuarine ecosystems in southern Portugal. The first approach to detect the presence of viruses was based on the occurrence of dsRNA, typically considered as a viral molecule in plants and fungi. Two dsRNA-banding patterns (∼7 and 9 kb) were observed in seven of 73 <i>Halophytophthora</i> isolates tested (9.6%). Consequently, two dsRNA-hosting isolates were chosen to perform stranded RNA sequencing for <i>de novo</i> virus sequence assembly. A total of eight putative novel virus species with genomic affinities to members of the order <i>Bunyavirales</i> were detected and their full-length RdRp gene characterized by RACE. Based on the direct partial amplification of their RdRp gene by RT-PCR multiple viral infections occur in both isolates selected. Likewise, the screening of those viruses in the whole collection of <i>Halophytophthora</i> isolates showed that their occurrence is limited to one single <i>Halophytophthora</i> species. To our knowledge, this is the first report demonstrating the presence of negative (-) ssRNA viruses in marine oomycetes.