Viral load differences associated with infection outcomes and resistance to white spot syndrome virus (WSSV) infection in mud crab, Scylla serrata.

White spot syndrome virus (WSSV), the causative agent of white spot disease, remains a serious threat to crustacean aquaculture. Infecting a wide range of crustaceans, host species exhibit varying susceptibility and mortality rates. Mud crabs, Scylla serrata, a high-value aquaculture commodity across the Indo-Pacific region, are known to be relatively resistant to WSSV.

Summary of taxonomy changes ratified by the International Committee on Taxonomy of Viruses (ICTV) from the Animal DNA Viruses and Retroviruses Subcommittee, 2025.

The International Committee on Taxonomy of Viruses (ICTV) holds a ratification vote annually after review of newly proposed taxa by ICTV Study Groups and members of the virology community. In March 2025, the vote outcome of the 11 proposals within the mandate of the Animal DNA Viruses and Retroviruses Subcommittee was made public. Here, we provide a summary of the newly accepted proposals.

Microbiome dynamics associated with Hematodinium sp. infection in Norway lobster (Nephrops norvegicus).

Background: The parasite Hematodinium sp. causes morbidity and seasonal mortality events in more than 40 decapod species globally and therefore, it is now recognised as a significant threat to the future sustainability of shellfish fisheries and aquaculture worldwide. Among these, Norway lobster (Nephrops norvegicus), an important representative of the marine benthos and supporting the most valuable shellfish fishery in the UK, experience yearly seasonal Hematodinium sp.

Identification of Albopleistophora grylli n. gen. n. sp. (Microsporidia) and its impact on crickets (Gryllus spp.) in food-and-feed culture systems.

This study provides a comprehensive taxonomic description of a microsporidian parasite infecting crickets, Gryllus bimaculatus and G. assimilis. Our analysis includes gross pathology, histopathology, spore ultrastructure, parasite development cycle, single gene phylogenies, and phylogenomic comparisons.

Pseudohepatospora borealis n. gen. n. sp. (Microsporidia: Enterocytozoonida): A microsporidian pathogen of the Jonah crab (Cancer borealis).

The microsporidian diversity catalogued so far has resulted in the development of several taxonomic groups, one of which is the Enterocytozoonida - a group of generalist 'ultimate opportunists', which infect many fished and aquacultured animals, as well as a broad suite of host taxa, including humans. In this study, we provide phylogenetic, ultrastructural, developmental, and pathological evidence for the creation of a new genus and species to hold a microsporidian parasite of the Jonah crab, Cancer borealis. Cancer borealis represents a species of commercial interest and has become the target of a recently developed fishery on the USA and Canadian Atlantic coast.

Resistance to white spot syndrome virus in the European shore crab is associated with suppressed virion trafficking and heightened immune responses.

Introduction: All decapod crustaceans are considered potentially susceptible to White Spot Syndrome Virus (WSSV) infection, but the degree of White Spot Disease (WSD) susceptibility varies widely between species. The European shore crab can be infected with the virus for long periods of time without signs of disease. Given the high mortality rate of susceptible species, the differential susceptibility of these resistant hosts offers an opportunity to investigate mechanisms of disease resistance.

Discovery of the parasite Marteilia cocosarum sp. nov. In common cockle (Cerastoderma edule) fisheries in Wales, UK and its comparison with Marteilia cochillia.

Diseases of bivalve molluscs caused by paramyxid parasites of the genus Marteilia have been linked to mass mortalities and the collapse of commercially important shellfish populations. Until recently, no Marteilia spp. have been detected in common cockle (Cerastoderma edule) populations in the British Isles.

High prevalence of Paramarteilia canceri infecting velvet swimming crabs Necora puber in Ireland.

The velvet swimming crab Necora puber has been fished in Ireland since the early 1980s and contributes significant income to smaller fishing vessels. From 2016 onwards, reduced landings have been reported. We undertook a full pathological investigation of crabs from fishing grounds at 3 sites on the west (Galway), southwest (Castletownbere) and east (Howth) coasts of Ireland.

Global mRNA and miRNA Analysis Reveal Key Processes in the Initial Response to Infection with WSSV in the Pacific Whiteleg Shrimp.

White Spot Disease (WSD) presents a major barrier to penaeid shrimp production. Mechanisms underlying White Spot Syndrome Virus (WSSV) susceptibility in penaeids are poorly understood due to limited information related to early infection. We investigated mRNA and miRNA transcription in over 36 h following infection.

Patterns of infection in a native and an invasive crayfish across the UK.

Invasive crayfish and the introduction of non-native diseases pose a significant risk for the conservation of endangered, white-clawed crayfish (Austropotamobius pallipes). Continued pollution of waterways is also of concern for native species and may be linked with crayfish disease dynamics. We explore whether crayfish species or environmental quality are predictors of infection presence and prevalence in native A.

A Novel RNA Virus, Macrobrachium rosenbergii Golda Virus (MrGV), Linked to Mass Mortalities of the Larval Giant Freshwater Prawn in Bangladesh.

Mass mortalities of the larval stage of the giant freshwater prawn, , have been occurring in Bangladesh since 2011. Mortalities can reach 100% and have resulted in an 80% decline in the number of hatcheries actively producing . To investigate a causative agent for the mortalities, a disease challenge was carried out using infected material from a hatchery experiencing mortalities.

Isolation of a Chinook Salmon Bafinivirus (CSBV) in Imported Goldfish L. in the United Kingdom and Evaluation of Its Virulence in Resident Fish Species.

This is the first record of a fish nidovirus isolated from a consignment of goldfish at the United Kingdom (UK) border. The full-length viral genome was 25,985 nt, sharing a 97.9% nucleotide identity with the Chinook salmon bafinivirus (CSBV) NIDO with two deletions of 537 and 480 nt on the ORF Ia protein.

Insights into the development of hepatocellular fibrillar inclusions in European flounder (Platichthys flesus) from UK estuaries.

Hepatocellular fibrillar inclusions (HFI) are an unusual pathology of unknown aetiology affecting European flounder (Platichthys flesus), particularly from estuaries historically impacted by pollution. This study demonstrated that the HFI prevalence range was 6-77% at several UK estuaries, with Spearman rank correlation analysis showing a correlation between HFI prevalence and sediment concentrations of ∑PBDEs and ∑HBCDs. The data showed that males exhibit higher HFI prevalence than females, with severity being more pronounced in estuaries exhibiting higher prevalence.

How do abiotic environmental conditions influence shrimp susceptibility to disease? A critical analysis focussed on White Spot Disease.

White Spot Syndrome Virus (WSSV) causes White Spot Disease (WSD) and is historically the most devastating disease in the shrimp industry. Global losses from this disease have previously exceeded $3 bn annually, having a major impact on a global industry worth US$19 bn per annum. Shrimp are cultured predominantly in enclosed ponds that are subject to considerable fluctuations in abiotic conditions and WSD outbreaks are increasingly linked to periods of extreme weather, which may cause major fluctuations in pond culture conditions.

A New Family of DNA Viruses Causing Disease in Crustaceans from Diverse Aquatic Biomes.

Panulirus argus virus 1 (PaV1) is the only known virus infecting the Caribbean spiny lobster () from the Caribbean Sea. Recently, related viruses, Dikerogammarus haemobaphes virus 1 (DhV1) and Carcinus maenas virus 1 (CmV1), have been detected in the demon shrimp () and the European shore crab (), respectively, from sites in the United Kingdom. The virion morphology of these crustacean viruses is similar to that of iridoviruses.

The first clawed lobster virus Homarus gammarus nudivirus (HgNV n. sp.) expands the diversity of the Nudiviridae.

Viral diseases of crustaceans are increasingly recognised as challenges to shellfish farms and fisheries. Here we describe the first naturally-occurring virus reported in any clawed lobster species. Hypertrophied nuclei with emarginated chromatin, characteristic histopathological lesions of DNA virus infection, were observed within the hepatopancreatic epithelial cells of juvenile European lobsters (Homarus gammarus).

Green crab Carcinus maenas symbiont profiles along a North Atlantic invasion route.

The green crab Carcinus maenas is an invader on the Atlantic coast of Canada and the USA. In these locations, crab populations have facilitated the development of a legal fishery in which C. maenas is caught and sold, mainly for use as bait to capture economically important crustaceans such as American lobster Homarus americanus.

Development and application of a duplex PCR assay for detection of Crangon crangon bacilliform virus in populations of European brown shrimp (Crangon crangon).

Crangon crangon bacilliform virus (CcBV) was first discovered in 2004 in European brown shrimp (Crangon crangon) caught along the English coast. This study describes a duplex PCR assay developed for the detection of CcBV, based on amplification of the lef-8 gene (211 bp) of CcBV and the E75 gene (105 bp) of C. crangon as an internal amplification control.

Reprint of 'Diseases in marine invertebrates associated with mariculture and commercial fisheries'.

Diseases in marine invertebrates are increasing in both frequency and intensity around the globe. Diseases in individuals which offer some commercial value are often well documented and subsequently well studied in comparison to those wild groups offering little commercial gain. This is particularly the case with those associated with mariculture or the commercial fisheries.

Molecular Mechanisms of White Spot Syndrome Virus Infection and Perspectives on Treatments.

Since its emergence in the 1990s, White Spot Disease (WSD) has had major economic and societal impact in the crustacean aquaculture sector. Over the years shrimp farming alone has experienced billion dollar losses through WSD. The disease is caused by the White Spot Syndrome Virus (WSSV), a large dsDNA virus and the only member of the Nimaviridae family.

Diseases in marine invertebrates associated with mariculture and commercial fisheries.

Diseases in marine invertebrates are increasing in both frequency and intensity around the globe. Diseases in individuals which offer some commercial value are often well documented and subsequently well studied in comparison to those wild groups offering little commercial gain. This is particularly the case with those associated with mariculture or the commercial fisheries.