Sessions

Sturgeons (Acipenseridae) are among the economically important species in intensive aquaculture. Their processed roe is caviar, which is considered a luxury product in gastronomy; they are also farmed for their meat. However, intensive rearing under high stocking densities predisposes fish to infectious diseases that may cause substantial losses. Acipenser iridovirus-European (AcIV-E) is one of those pathogens that has not previously been documented in Hungary. It was previously classified within the family Iridoviridae, however, recent studies have revealed a greater similarity to the members of the family Mimiviridae.

The aim of our research was to detect the virus in Hungarian Russian sturgeon (Acipenser gueldenstadtii, Brandt & Ratzeburg, 1833) stocks and to document its distribution within the country. Sampling was carried out in spring and summer of 2025 at three Hungarian sturgeon farms. One of the examined farms had juvenile Russian sturgeons showing clinical signs (abnormal swimming behaviour, whirling, anorexia, haemorrhages) which did not respond to the previous antibiotic treatment. Necropsy was performed on the affected juveniles. Each recirculation system was treated as one unit and gill and mucus samples were collected from five adult fish in each unit. After extracting the DNA from the samples, the virus was identified using PCR. AcIV-E were detected in all three farms in symptomatic juveniles.

These results demonstrate that AcIV-E has already emerged in Hungary and by now it is present at an increasing number of sturgeon farms, causing significant economic losses among juvenile sturgeons. The detection of the virus in asymptomatic adult fish reveals their potential role as carriers, posing a risk to younger populations kept in the same facilities. This study provides the first evidence of AcIV-E in Hungary and highlights its veterinary and economic significance. Whole genome sequencing and precise taxonomic classification of the virus are subjects of current studies, while further research is needed to clarify its distribution, pathogenicity, and impact on farmed sturgeon populations. Our results may contribute to the development of effective biosecurity strategies and support the long-term sustainability of domestic sturgeon farming and caviar production.