Nilanjana Das | Geology Reports

USGS2025

Detection and genetic characterization of red-spotted grouper nervous necrosis virus and a novel genotype of nervous necrosis virus in black sea bass from the U.S. Atlantic coast

Nervous necrosis virus (NNV) causes a neurologic disease in a wide range of marine fish and poses serious disease risks to marine aquaculture worldwide. Little is known about the presence of NNV along the Atlantic coast of the United States, aside from the presence of barfin flounder nervous necrosis virus (BFNNV) in coldwater species in the northern part of this range. Herein we conducted surveillance for NNV from 2020 to 2022 in the mid-Atlantic region of the United States in black sea bass Centropristis striata , a serranid fish that is found throughout the eastern U.S. coast. Molecular detection methods have identified and characterized red-spotted grouper nervous necrosis virus (RGNNV) sequences at low prevalence throughout the years. Further, in 2022, a higher prevalence of a novel NNV genotype, tentatively named black sea bass nervous necrosis virus (BSBNNV), was characterized for the first time. Though virus isolation was unsuccessful, this study was the first to genetically identify NNV in this region and in this species. These findings highlight the need for further research on NNV to understand epidemiology and virulence in the context of marine fisheries and an emerging marine aquaculture industry in the United States.

New Jersey↗

USGS2024

Seasonal mortality of Wild Atlantic Menhaden (Brevoortia tyrannus) is caused by a virulent clone of Vibrio (Listonella) anguillarum; Implications for biosecurity along the Atlantic Coastal United States

Atlantic menhaden are a highly migratory marine species in the Eastern United States that suffer from seasonal chronic mortality. Affected fish show neurologic signs referred to as spinning disease, including circling at the surface and erratic corkscrew swimming before death. We investigated three similar menhaden mortality events consistent with spinning disease in coastal New Jersey and New York between 2020 and 2021 to understand the cause. A unique strain of Vibrio (Listonella) anguillarum (serogroup O3) was detected regularly in high loads, particularly in the brains of moribund fish, by both metagenomics and bacterial isolation. The most common histopathological changes in moribund fish were hemorrhagic meningitis, encephalitis, pyknosis, and karyorrhexis of hematopoietic tissues in the kidney and spleen. Whole genome sequencing of isolates from moribund fish representing a wide spatial and temporal range showed that they were nearly identical clones, suggesting it to be a pathogenic strain circulating in the population. Though V. anguillarum is believed to be the main pathogen associated with spinning disease and mortality, Yersinia ruckeri (serotype O1) was isolated from smaller numbers of fish. Considering the highly migratory nature of Atlantic menhaden throughout the eastern United States and their use as bait for other fisheries, these findings identify potential biosecurity challenges that should be considered in Atlantic salmon aquaculture, fisheries, and emerging marine aquaculture in the region.

Transboundary and Emerging Diseases↗