Identification of a newly described OsHV-1 µvar from the North Adriatic Sea (Italy).

Miriam Abbadi,Alessia Schivo,Umberto Rosani,Adelaide Milani,Lorenzo Gennari,Anna Toffan,Paola Venier,Giuseppe Arcangeli,Emanuele Rossetti,Edoardo Turolla,Francesco Pascoli,Gianpiero Zamperin,Michele Gastaldelli

doi:10.1099/jgv.0.001042

Abstract

The surveillance activities for abnormal bivalve mortality events in Italy include the diagnosis of ostreid herpesvirus type 1 (OsHV-1) in symptomatic oysters. OsHV-1-positive oysters (Crassostrea gigas) were used as a source for in vivo virus propagation and a virus-rich sample was selected to perform shotgun sequencing based on Illumina technology. Starting from this unpurified supernatant sample from gills and mantle, we generated 3.5 million reads (2×300 bp) and de novo assembled the whole genome of an Italian OsHV-1 microvariant (OsHV-1-PT). The OsHV-1-PT genome encodes 125 putative ORFs, 7 of which had not previously been predicted in other sequenced Malacoherpesviridae. Overall, OsHV-1-PT displays typical microvariant OsHV-1 genome features, while few polymorphisms (0.08 %) determine its uniqueness. As little is known about the genetic determinants of OsHV-1 virulence, comparing complete OsHV-1 genomes supports a better understanding of the virus pathogenicity and provides new insights into virus–host interactions.

Highlights

The surveillance activities for abnormal bivalve mortality events in Italy include the diagnosis of ostreid herpesvirus type 1 (OsHV-1) in symptomatic oysters
Ostreid herpesvirus type 1 (OsHV-1) was firstly detected from Crassostrea gigas larvae during mortality events in French hatcheries in 1991 [1, 2] and it was progressively associated with the mass mortality of oyster spats and juveniles in Europe and other regions of the world [3,4,5,6,7,8]
The bivalve farming industry is economically relevant for the regions bordering the Adriatic Sea and, even if the production of the Pacific oyster is at its onset, the global diffusion of infectious OsHV-1 microvariants raises significant concern in the national authorities and farmers

Summary

SHORT COMMUNICATION

Abbadi et al, Journal of General Virology 2018;99:693–703 DOI 10.1099/jgv.0.001042 Identification of a newly described OsHV-1 μvar from the North Adriatic Sea (Italy) Miriam Abbadi,1,2,* Gianpiero Zamperin,1 Michele Gastaldelli,1 Francesco Pascoli,1 Umberto Rosani,2 Adelaide Milani,1 Alessia Schivo,1 Emanuele Rossetti,3 Edoardo Turolla,4 Lorenzo Gennari,5 Anna Toffan,1 Giuseppe Arcangeli1 and Paola Venier2,*

No of injected oysters

Negative Negative

Positive Negative Positive Positive Negative

DNA packaging

Findings

Catalytic subunit DNA polymerase