“Detection of Acipenserid Herpesvirus type 2 (AciHV-2) in Italian Sturgeon Farms (7182)”

Detection of Acipenserid Herpesvirus type 2 (AciHV-2) in Italian Sturgeon Farms

Introduction

Sturgeon farming for caviar production is rapidly expanding in Europe. Italy is the European leader country in the sector with a caviar output of 65 tons per year and it is second in worldwide market only to China. Although sturgeons are considered relatively disease-resistant compared to other fish species, they are susceptible to bacterial, parasitic and viral pathogens. Viruses of the Herpesviridae and Iridoviridae families are the major threats and are the most reported causes of mortality outbreaks in sturgeons (with peaks of up to 95% of mortality in young farmed sturgeon). Historically, Acipenserid herpesvirus type 1 (AciHV-1) was detected in sturgeon farms in Italy but no evidences of the active circulation of other AciHVs are available.

Methodology

Necropsy, bacteriological and parasitological examinations were performed according to standard procedures on sturgeons belonging to different species and coming from different Italian farms suffering mortalities.

Samples of gills or organ pools were screened for the presence of AciHV. The organs were tested by virus isolation on White Sturgeon Skin cell line (WSSK-1). The samples showing cytopathic effect were propagated on cell, observed by transmission electron microscopy (TEM) and tested with different molecular assays. DNA was extracted and analysed for AciHV detection with already published and newly developed molecular methods: real time, conventional and nested PCR. The oligonucleotides of molecular tests were designed on three different target genes and PCR amplicons were subjected to Sanger sequencing. Five isolates were fully sequenced with Next Generation Sequencing.

Results

The presence of AciHV-2 only was detected in samples of Acipenser gueldenstaedtii and Acipenser Baerii collected over the last ten years from Italian farms. Affected sturgeons commonly showed cutaneous lesions, ascites, internal haemorrhages and mortality. Not all the molecular assays tested against AciHV consistently confirmed cell culture and TEM positive results. The best method for diagnostic screening resulted to be a Taqman Real-Time PCR, targeting a portion of the AciHV-2 DNA packaging terminase gene.

Conclusions

This work demonstrates for the first time AciHV-2 virus circulation in Italian sturgeon farms. This result was achieved through the development of an effective and rapid diagnostic molecular method that we suggest to apply in case of AciHV suspicion. Considering the growing importance of the sturgeon farming and caviar production in Italy, it is recommended that general health surveillance tests are implemented, especially for viral diseases in order to avoid their spread and reduce losses in sturgeon farms.

1. BIASINI, LORENA, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Presenter
2. Buratin, Alessandra, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author
3. Berto, Paola, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author
4. Lucon Xiccato, Romy, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author
5. Marsella, Andrea, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author
6. Pretto, Tobia, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author
7. Cortinovis, Luana, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author
8. Toffan, Anna, ISTITUTO ZOOPROFILATTICO SPERIMENTALE DELLE VENEZIE, Author