Molecular immune response of the American lobster (Homarus americanus) to the White Spot Syndrome Virus

• First transcriptomic study of American lobster immune response to viral challenge.
• Homarus americanus immune response to WSSV challenge.
• 136 Differentially expressed genes identified in H. americanus immune response.
• Differential expression of thioredoxin, cathepsin and trypsin isoforms.
• WSSV replication in American lobster tissues.

The adult American lobster (Homarus americanus) is susceptible to few naturally occurring pathogens, and no viral pathogen is known to exist. Despite this, relatively little is known about the H. americanus immune system and nothing is known about its potential viral immune response. Hundreds of rural communities in Atlantic Canada rely on the lobster fishery for their economic sustainability and could be devastated by large-scale pathogen-mediated mortality events. The White Spot Syndrome Virus is the most economically devastating viral pathogen to global shrimp aquaculture production and has been proposed to be capable of infecting all decapod crustaceans including the European Lobster. An in vivo WSSV injection challenge was conducted in H. americanus and WSSV was found to be capable of infecting and replicating within lobsters held at 20 °C. The in vivo WSSV challenge also generated the first viral disease model of H. americanus and allowed for the high-throughput examination of transcriptomic changes that occur during viral infection. Microarray analysis found 136 differentially expressed genes and the expression of a subset of these genes was verified using RT-qPCR. Anti-lipopolysaccharide isoforms and acute phase serum amyloid protein A expression did not change during WSSV infection, contrary to previous findings during bacterial and parasitic infection of H. americanus. This, along with the differential gene expression of thioredoxin and trypsin isoforms, provides compelling evidence that H. americanus is capable of mounting an immune response specific to infection by different pathogen classes.

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