Accepted_test

Due to the problem of the emergence of new viral diseases and the expansion of the capabilities of molecular virology, the different projects are being implemented for massive parallel sequencing (mainly metatranscriptomic studies) of various species of invertebrate, including mollusks. Most studies have primarily focused on marine mollusks; much less attention has been paid to freshwater mollusks. In our study, we estimated the viral diversity in samples of the Baikal endemic gastropod Benedictia baicalensis using metatranscriptomic analysis.

In metatranscriptomic data from the samples of Baikal mollusks we revealed 64 viral scaffolds; of these, one was identified as a DNA virus related to ssDNA CRESS viruses. The rest 63 viral scaffolds were identified as RNA viruses similar to those from different viral families with a wide range of hosts (mollusks, insects, algae and others).

Among the viral genomes identified were picorna-like viruses closely related to the previously described freshwater shellfish viruses Biomphalaria virus 1 and Biomphalaria virus 3.

The similarity of proteins of B. baicalensis viruses to known viruses from the NCBI database was low and in single cases exceeded 70%. However, one scaffold showed 99.3% identity and 99% query coverage with unstructured polyprotein of Tiger puffer nervous necrosis virus (family Nodaviridae). Thus, Baikal mollusks may also act as reservoirs for nodaviruses as well as other viruses and influence their epidemiology.

In general, our data revealed significant distances between the RdRps genes of Baikal viruses and those from other organisms and biotopes, indicating the novelty of the viruses we discovered.