White spot syndrome virus (WSSV) in Alabama red swamp crayfish (Procambarus clarkii)

Authors: BRUCE, TIMOTHY - Auburn University; Abernathy, Jason; TRIPP, NICOLE - Auburn University; BARNES, NICHOLAS - Auburn University; HARRISON, COURTNEY - Auburn University; OLADIPUPO, ABDULMALIK - Auburn University; Krol, Justin; WISE, ALLISON - Auburn University; WARG, JANET - Animal And Plant Health Inspection Service (APHIS); STOECKEL, JAMES - Auburn University

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2023
Publication Date: 10/18/2023
Citation: Bruce, T.J., Abernathy, J.W., Tripp, N., Barnes, N., Harrison, C.E., Oladipupo, A.A., Krol, J.D., Wise, A.L., Warg, J.V., Stoeckel, J.A. 2023. White spot syndrome virus (WSSV) in Alabama red swamp crayfish (Procambarus clarkii). Journal of Fish Diseases. 47(2):e13873. https://doi.org/10.1111/jfd.13873.
DOI: https://doi.org/10.1111/jfd.13873

Interpretive Summary: The red swamp crayfish (Procambarus clarkii) is a prominent species in the southern United States and has been introduced into many regions for food production stocks. In 2018, there were 482 crayfish farms in the U.S., with an estimated total sales of $50.8 million and growing. As with the accelerated spread of aquatic species and increased production facilities, crayfish diseases soon followed. White spot syndrome virus (WSSV), a circular, double stranded DNA virus of the family Nimaviridae is a global concern for crustacean producers, as it is responsible for white spot disease (WSD). The first cases of WSSV in farmed and wild crayfish in the U.S. date back to 2007, when three farms producing Louisiana crayfish experienced heavy mortality rates in the spring season. There are limited reports on the overall implications for WSSV within the crayfish industry, and the geographic spread also remains unknown. In spring 2022, WSSV was detected in red swamp crayfish at the E.W. Shell Fisheries Center at Auburn University (Auburn, AL) and resulted in mortalities within laboratory-reared animals. This is known to be the first report of WSSV within Alabama, a state that is home to a diverse population of 99 different species of crayfish. This case report details the discovery, confirmation, genome sequence, and genetic characterization of the WSSV isolate at the location.

Technical Abstract: The red swamp crayfish (Procambarus clarkii) is a prominent species in the southern United States and has been introduced into many regions for food production stocks. A growing industry, with the accelerated spread of aquatic species and increased production facilities, crayfish diseases have been reportedly rising. White spot syndrome virus (WSSV), a circular, double stranded DNA virus of the family Nimaviridae is a global concern for crustacean producers, as it is responsible for white spot disease (WSD) in shrimp and prawn facilities, and increasingly in crayfish aquaculture. There are limited reports on the overall implications for WSSV within the crayfish industry, and the geographic spread also remains unknown. In spring 2022, WSSV was detected in red swamp crayfish at the E.W. Shell Fisheries Center at Auburn University (Auburn, AL) and resulted in mortalities within laboratory-reared animals. This is known to be the first report of WSSV within Alabama, a state that is home to a diverse population of 99 different species of crayfish. This case report details the discovery, confirmation, genome sequence, and genetic characterization of the WSSV isolate at the location. First, clinical signs of the disease were characterized. Then, confirmation PCR on the WSS1011F/WSS1079R gene region was performed. Viral load was quantified from the gills and abdomen. Total DNA from a heavily-infected red swamp crayfish was isolated and processed for Oxford Nanopore Technologies sequencing with Adaptive Sampling. After bioinformatic processing, a high-quality genome assembly of WSSV was produced, with length of 285,974 bp and G/C content of 41.2%. Annotation of the genome revealed 199 genes with average length of 1,313 bp. Phylogenetic analyses indicated that the isolate is unique from currently known WSSV genomes that have been previously isolated from either shrimp/prawns or crayfish.