Authors
Samson, J. S., Rowley, D., Gomez-Chiarri, M.
Abstract
Bacterial pathogens cause disease outbreaks in hatcheries, resulting to larval mortality and significant economic losses. One of the major challenges in studying bacterial pathogenesis in larvae is the limited availability of healthy larvae throughout the year. This seasonal constraint delays testing and impedes progress in understanding bacterial infections, disease management, and the development of effective treatments for bivalve aquaculture. To address this challenge, a hemocyte viability assay based on the resazurin assay was developed as an alternative for testing bacterial pathogenesis. The assay was optimized using eastern oyster hemocytes, and the lethal concentration (LC)50 values of a well-known bacterial pathogen of larvae (Vibrio coralliilyticus RE22) (107 {+/-} 22 multiplicity of infection (MOI)), a probiont (Phaeobacter inhibens S4) (2157 {+/-} 167 MOI), and several bacterial isolates from shellfish hatcheries were determined. The most virulent isolates had an LC50 ranging from 53 to 195 MOI, indicating high pathogenicity. To validate the assay, the isolates were tested on oyster larvae, confirming that bacterial isolates with low LC50 (<200 MOI) caused significant larval mortality, while other isolates exhibiting LC50 values ranging from 690 to 25389 MOI showed no adverse effect on the oyster larvae. This high-throughput hemocyte viability assay provides a reliable and less time-consuming alternative to larval assays, particularly during the off-season, facilitating year-round research on bacterial pathogenicity in bivalves.
Preprint server:
bioRxiv
The authors list and abstract were imported from bioRxiv on 06 Nov 2025.
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