Complete genome sequence of Ostreid herpesvirus-1 associated with mortalities of Scapharca broughtonii broodstocks.

ABSTRACT:

Background

Ostreid herpesvirus-1 (OsHV-1) is the major bivalve pathogen associated with severe mortality events in a wide host range. In the early summer of 2012 and 2013, mass mortalities of blood clam (Scapharca broughtonii) broodstocks associated with a newly described variant of OsHV-1 (OsHV-1-SB) were reported.

Methods

In this study, the complete genome sequence of the newly described variant was determined through the primer walking approach, and compared with those of the other two OsHV-1 variants.

Results

OsHV-1-SB genome was found to contain 199, 354 bp nucleotides with 38.5% G/C content, which is highly similar to those of acute viral necrosis virus (AVNV) and OsHV-1 reference type. A total of 123 open reading frames (ORFs) putatively encoding functional proteins were identified; eight of which were duplicated in the major repeat elements of the genome. The genomic organization of OsHV-1-SB could be represented as TRL-UL-IRL-IRS-US-TRS, which is different from that of OsHV-1 reference type and AVNV due to the deletion of a unique region (X, 1.5Kb) between IRL and IRS. The DNA sequence of OsHV-1-SB is 95.2% and 97.3% identical to that of OsHV-1 reference type and AVNV respectively. On the basis of nucleotide sequences of 32 ORFs in OsHV-1-SB and the other nine OsHV-1 variants, results from phylogenetic analysis also demonstrated that OsHV-1-SB is most closely related to AVNV.

Conclusions

The determination of the genome of OsHV-1 with distinguished epidemiological features will aid in our better understanding of OsHV-1 diversity, and facilitate further research on the origin, evolution, and epidemiology of the virus.

SUBMITTER: Xia J 

PROVIDER: S-EPMC4514999 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature